Rick Shory

Offering a little something you might not otherwise have


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Pear grafts eliminate invasive hawthorn

Topworking pear can effectively remove invasive hawthorn (Crataegus monogyna) trees by replacing all seed-bearing limbs. A side benefit is edible pears.


It seems whenever I would teach a grafting class, some young guy would pipe up and say, “I read you can graft pear onto hawthorn. Is it true?”

All I could answer was, “I don’t know. Lets give it a try!”

But it was easier said that done. For all the ubiquity of weedy hawthorn trees through the Northwest, it took years to find some I could try grafting onto. I certainly did not want to plant any more of these thorny trees for the experiment. There are far too many of them already.

hawthorn leaves

Hawthorn leaves

Finally, last spring I got to know a property owner whose land was infested by hawthorn trees, and he welcomed me to give it a go.


During the period of April 17 to April 28, I topworked several hawthorn trees.

topworking diagram

I sawed them off and bark-grafted them to pear.

bark grafts

Bark grafts

I used the standard technique of my video.

 

By July a lot of them had grown out abundantly.

new shoots

Growth by July

But not all. This is why.

deer

Deer were standing by, curious what this human had been up to.


The long term outcome of grafting goes far beyond the compatibility of scion on stock. The main reason to graft pear onto hawthorn is to “eliminate” weedy hawthorn trees.

It may not be evident how topworking does this. You might argue, the major part of the hawthorn tree is still there. Well, the tree itself is not invasive. It is rooted in one spot, and can’t move.

What’s invasive are the seeds. Left to itself, a hawthorn tree blooms every year, and makes thousands of small red berries. These get spread around, and new sprouts come up.

hawthorn berries

Hawthorn fruits are technically “pomes”, like small apples.

After a hawthorn tree is topworked to pear, it does not bloom hawthorn flowers any more. The blossoms are pear, as showy white in springtime as the thorn flowers used to be.

The fruit, instead of hawthorn berries, is now pears. Even if nobody eats them, there are no more hawthorn seeds from that tree. Even if the pear crop fails.

What’s more, people are now interested in that tree. They come to it for fruit in the fall. Where it was once a thorny part of the landscape, nondescript except for a few bloom weeks in the spring, now it’s a focal point.

Years later, even if people don’t understand what it is, they will know “that pear tree”. They will be invested in the care of the land, and the area.

If they do understand what it is, they will support the same work on more hawthorn trees, thus curbing the spread of this invasive.


Deer are browsers. They want to eat tender new growth. This is exactly what fruit tree grafts are, in the critical stage going from the dormant scions you put in place, to the replacement limbs you want them to become.

Most hawthorn trees that are candidates for topworking are in open land, exposed to deer.

Deer browse to a height which is approximately shoulder-level on a human, depending how tall you are and how desperately hungry are the deer.

work and browse height diagram

The easiest height to topwork trees is, unfortunately, a smorgasbord for deer.


Why not graft higher?

First, take note that the grafted-on parts are going to grow upward. There will be very little fruit at or below the level where you graft. Practically all will be above. To eventually reach the fruit, you want to graft as low as possible.

reach height diagram

It may not be obvious until you try it, but grafting at or above eye level is a big step up in difficulty.

bark graft above eye level

Grafting at or above eye level is awkward.

You cannot easily move around to all sides of the work, to clearly see what you are doing. You need a ladder, or at least a stump, to stand on. This is immediately problematic, especially on uneven ground. The fruit that eventually appears will be all that much further up in the sky.


This first try of grafting pear on hawthorn has been a demo in many ways.

Whether or not the grafts themselves were compatible, I knew deer would be a problem. I intentionally did some grafts where I thought deer would eat them. Sure enough, the deer did.

The test case was a hawthorn tree that was originally leaning across a path. Once cut, the end was right by the path, and low down.

low cut stump

Shortly after doing this doomed graft, I had a friend stand there for scale. You can see the grafted trunk is well below shoulder height.

person showing height scale

Grafts relative to shoulder level.

Deer can be dainty eaters. They nip off the tender shoots, but have less interest in the woody scions themselves. Below is a picture of a scion gamely trying to re-grow after being browsed.

browsed graft

The clue that there used to be a healthy shoot on top is the full-sized leaf below. Top buds grow first, but all that remains is a stub.

To the casual glance, it may look like a grafts never “took”, or barely did.

browsed graft

Sometimes browse is evident, as bitten-off twigs.

bitten off shoot

After a couple cycles of this, the grafts die. The stock tree itself may die, or at least be strongly set back, because it is depending on the new leaves from the grafts for photosynthesis.

It’s important to distinguish whether a graft was incompatible, that is something inherently wrong with it. Or if the graft itself was fine, but got eaten.

bitten off scions

In my test case, the proof is the chomp marks. Here, the deer were so enthusiastic, they bit into the woody scions themselves.


Is topworking in open land futile?

This demo was a test of many things, including deer browse deterrence.

Of the various things I tried, the one that worked best was piling brush around the trees. This was the thorny branches left over from preparing the trees.

brush barrier diagram

I piled brush waist high, chest high if there was enough, to completely surround the trunks. I could not have got to the trees afterwards myself. I’m sure the deer could have got through if they really wanted to, but they moved on to easier pickings.


There are many questions still to answer.

I tried first bark grafting because it is the appropriate technique on large-trunked trees. But there could be better methods.

In summer, I found some small shoots the right size for bud grafting, and tried some of those.

new bud graft

By now, they look well healed.

bud graft healed

Some even sprouted during the summer growing season. This usually indicates good compatibility.

bud graft grown


All the pear varieties I tried did grow well, if not browsed. But there are hundreds of kinds of pear. It could be that some are graft-compatible on hawthorn and others are not, as on some quince rootstocks widely used for pear.

It’s not yet clear whether grafting on hawthorn dwarfs pear, which would be desirable.

Hawthorn trees seldom appear to suffer drought stress in our dry Northwest summers, so it could be they will support pear without irrigation. Or the opposite might be true, and the grafts will fail, or lose their crop, under drought.

There might be some long-term delayed incompatibility, as in grafting pears onto apples.


To get answers, I would be interested to try grafting pears onto hawthorn at other sites. If you have a place to try, please get in touch.

rickshory@gmail.com

bud flagged


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Persimmon bud grafting

Proper handling of persimmon bud scions is vital, but does chilling help or hurt?


Summer bud grafting is usually high-success, but when I first started on persimmons I had a mysterious run of failures. The bud sticks looked perfectly fine, and the buds appeared healthy, but the bud scions would dry up and fall out of the stock twigs. It happened both from T-budding and chip budding. Not always, but sometimes a whole batch would fail.

This amounted to a minor disaster. It can take considerable logistics to get bud sticks the right time of year, the second week of July. If I’d suspected the grafts would all fail, I might have been able to go get more scions, and re-try later that same summer. But I did not notice till autumn, far too late to try again. So, I lost a whole year of potential growth. Not to mention the discouragement of all the grafts failing, and not knowing why.

Over time I thought about it. I wondered if, unsuspecting, I had handled the scions wrong, and killed them. I remembered a friend, who ran a farm stand, insisting you should never put tomatoes in the refrigerator. “It changes the enzymes,” he said, “And they never get the flavor back.” It crossed my mind that, just possibly, chilling a plant is not always a harmless mode of storage.

I had long been in the habit of storing scions in the refrigerator. It’s a convenient way to stretch winter dormancy into spring, or even summer, such as for bark grafting. It was second nature to keep precious scions “fresh” in the refrigerator.

Now, I had to re-think this. What if chilling twigs in summer, when they are not dormant, damages them? What if this was why my bud grafts failed? I tried to remember if I had indeed put those bud sticks in the refrigerator. It was so natural to chill produce, I could not remember.

However, I started to avoid chilling summer-cut bud sticks, particularly persimmon. Grafting is time-lapse. You do your grafts, and then long afterwards you see your results. After a couple years, I realized my summer bud grafting success on persimmons was consistently high.

persimmon bud grafts growing

Persimmon bud grafts

I wondered if chilling had been the early problem, and I really wanted to know. Last summer, I had the opportunity for a proper experiment. A friend had an unproductive persimmon tree, and I offered to try grafting on it.

I took bud scion twigs from my Fuyu persimmon tree. I chose two sets of three twigs each, as nearly alike as I could make them.

two sets of twigs

Two sets of twigs

I put each set in its own produce bag. One bag, the control, I kept overnight in my basement, at moderate room temperature, about 70°F (21°C). The other bag spent the night in the refrigerator crisper, at about 40°F (4°C). In the morning both looked fine.

twigs in produce bags

Twigs kept the same except for chill

I went across town to the stock persimmon tree, and did ten bud grafts from each set. Actually, I did eleven of the chill because one bud got knocked off the bark.

I tied on pink flagging, to make them easy to see, prevent them getting accidentally pruned off.

bud flagged

Ribbon, for visibility

I chose good, healthy buds. I did both sets as nearly the same as I could. Here were the same variety of scions, on the same stock, on the same day, both cut off the original tree for the same period of time. The grafting date was July 19, 2020, a good hot day. Just what persimmons like.

persimmon bud grafts

Grafts completed in summer

On December 15, 2020, I went back to check. The results were exactly opposite of what I expected!

Of the buds kept chilled overnight, there were ten out of ten, 100% takes.

grafts that took

Chilled buds took

 

close up of good graft

Well-healed bud

Even the graft that had the bud knocked off had healed. So really eleven out of eleven.

Of the buds kept at room temperature overnight, there were 80% clear failure.

failed bud grafts

Buds kept at room temperature failed

It was the same failure mode I had seen before. The bud scion had fallen out, and black bark was healing in to the scar.

failed bud graft

Bud has fallen out, and black bark healed behind

Even the few bud scions still there were dried up, and the stock twig was healing from behind them. These looked thin and dry, peeling up from one end, as though they might actually be dead but just adhered to the stock twig.

chilled bud

Buds still present are not well healed.

They did not look like the obviously healthy chilled buds, where the stock growth had “melted” in around them, as though to glue them on.

healthy bud graft

Well healed bud looks melted into the twig


This result is so astonishing, I’m still not sure I believe it. What if I got the labels mixed up? What if those I thought were chilled were really not, and vise versa?

I will be doing further tests next year, but I am posting this now because the difference was so significant. 

You can try your own experiments, and see what you get.


There are questions to answer: 

Is there something magic about chilling? Can you cut the buds at your leisure, as long as you chill them later? Or is it the time at warm temperature that kills the buds? This is important in practical terms.

When you go get bud scions, you spend a certain amount of time out in the orchard, or at least traveling across town. If this elapsing time is the tick of death, how brief does it need to be?

You can’t take your refrigerator in your hip pocket. A chest cooler won’t actually cool anything, unless you put ice in it. Is ice too cold? This gets complicated.

What could it be about ordinary summer temperature that kills the buds? Is it simply drying out? If so, would it work as well to put scions quickly in water? That would be more portable than chilling.

I will be doing more tests next summer.


If summer bud grafting is so risky, why where mine working at all? I realized, in most cases, I was grafting the buds within a short time of cutting them off the source tree.

After they did take, they would grow very well.

tall shoots from bud grafts

Growth from persimmon bud grafts


If you can manage to cut persimmon buds and graft them instantaneously, it looks good. But if you are going to have material shipped, there is a bud grafting technique on persimmons that will work: Grafting dormant winter buds.

First, a quick overview of summer bud grafting, the usual way.

bud graft diagram

Bud grafting the usual way

It’s convenient to be able to take scions, and graft them in the same time frame. No risk of mishaps in storage, or forgetting about the stored material.

For this, the second week of July is ideal, the current year’s buds are formed (scion), and the current year’s twigs (stock) are well grown but still active. The scion bark peels, so T-budding is easy.

But if summer persimmon buds are problematic, you can use what I call “May budding”.

You harvest dormant persimmon twigs for their buds in winter. You keep them refrigerated, in a produce bag, so they stay asleep. Then, you graft them when the weather warms up in spring.

This is a variant of a technique called “June budding”. Real June budding is more for California, where they have a very long growing season. There, the current season’s growth has developed such that the bases of the new twigs are solid enough to graft buds onto by June.

You June-bud onto the twig bases using dormant buds, kept in cold storage since the previous winter. After a few weeks, when those buds have healed, you cut off above them and force them into their season’s growth.

The Northwest variant is to do this in May, in the first hot weather. The new growth is not big enough yet, so you graft buds onto the previous year’s twigs.

From here, it’s the same as June budding. For scions, you use buds from stored dormant twigs.

May budding diagram

Variant, bud grafting in May

Not every year-old stock twig may be suitable, but you will do little damage by trying.

Make the T-shaped cut in the stock, as though you were going to do T-budding. If the “ears” will peel back, go ahead. If not, you have only made a small wound, easily healed.

Try another place on a different stock twig, or later in spring.


We’ve got to figure out persimmon bud grafting. It can be very satisfactory for testing out a variety.

Since persimmons bear on their new growth, the shoot from a bud graft can produce blossoms and fruit the first year. The picture below shows this.

fruit from a bud graft

Persimmon fruit the first year from a bud graft

The leafy shoot is growing from a bud that was grafted on the previous summer. This picture is in July, and there are green persimmons already forming on that shoot, in its first year of growth.

These persimmons went on to ripen, and the twig continued growth in future years.

 


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Lightmeter lettuce

I was talking with some guys, how cool it would be to set up environmental monitoring stations at a permaculture. Measure how much solar energy gets to every different place. Maybe rain gauges, wind speed. Oh, it was glorious!

After a while I had to ask, “Well, how much would it cost?”

This one guy, excited, related he’d got all the parts for “only $40!”

So, a second one would be only twice the price. And three times. And four times.

“You know,” said, “When I’ve been involved in this sort of thing, the other side is the data. You get so much data, pretty soon you’re awash in it. No time to crunch the numbers.”

“What would be really nice,” I mused, “Is a sensor that automatically gives you an integrated readout. And an inexpensive sensor. Ideally it should be self-replicating.”

Then I got out the pictures of lettuce. This is all the same kind of lettuce, a variety “Red Sails”. Probably any red leaf lettuce would do.

This is what it looks like in shade, like up under a tree. Just green.

When it gets more light, such as in among other vegetables, it makes more red color.

Then, still more sunshine, like on the edge of a bed, still darker red.

In full blasting sun, like pavement cracks, it’s hard ruby red.

They guys were onboard. “Have you got this digitally interfaced yet?” They were excited.

“Oh, that would be easy,” I blandly replied. “Just have one laser, scanning over the garden. Zapping each one, and recording the readout.”

 “We could extend this,” I went on, “To ozone or pollution monitoring. How much it burns the leaves. At least compared to how much the laser burns the leaves.”

 “Yeah, right on!” they chorused.

 “And one final thing,” I summed up. “Defunct equipment disposal is easy. When you’re done with the sensors, just eat them.”

very ripe pear


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Using “overripe” fruit

People often throw away fruit that has even one soft spot. They’ll spit out in disgust an apple that’s mushy and mealy. Yet fruit at this far limit of ripeness actually makes the best cooked sauces.

When fruit is green, it’s hard and sour. It’s hard because the cells are firmly glued together by pectin. It’s sour because the carbohydrate is starch, which has no sweet taste.

cell structure of under ripe fruit

Unripe fruit is sour and hard

If you were to try to cook green fruit into sauce, it would never get sweet, because cooking doesn’t break down starch into sugar. What you might get, if you drain off the liquid, is a solution of pectin, useful for making jelly. This was the traditional way of getting pectin before it was a commercial product.

As fruit gets ripe, several processes occur. At the surface, the whole fruit changes color. Inside, the fruit tissues produce a mixture of esters, flavor molecules that give the characteristic essence of, say, apple, peach, or pear. If this fruity scent is not there before you cook fruit, there’s no way it can be there after!

The pectin that binds the cells, one to another, begins to break down, so the whole fruit gets softer.

cell structure of ripe fruit

ripe fruit is sweet and flavorful

The starch turns to sugar, and goes into each cell’s central vacuole. This vacuole is like a storage tank, which makes up most of the internal space of the cell. The fruit cells become like tiny water balloons, full of flavorful liquid.

When you bite into a piece of fruit that is perfectly ripe, your chewing crushes the cells open to release their sweetness and flavor.

As fruit gets past the point of perfect ripeness, the same processes go further. Esters build up even more, and can give the fruit an “off” flavor, even reminiscent of paint thinner. The starch continues to convert to sugar, and builds up even more in the cell interior.

cell structure of over ripe fruit

overripe fruit is excessively soft

If there’s so much sugar, why is an overripe apple mealy and bland? The pectin that used to glue the cells together is gone, so the cells come apart from each other when you chew. They roll around in your mouth like little BBs. They don’t pop open and release their sweetness.

If you take courage, and dare to cook fruit that has gone into this unpromising state, the magic happens. The heat drives off excess esters, and tones the flavor down. The cells burst open, and release all their internal sugar.

If there’s any complaint, it may well be that the product is “too sweet”. You can always blend it with something that could use additional sweetness, or use it as a sweetener in its own right. Some years ago, there was a spate of natural products advertised as “pear juice sweetened”. This is where that pear sweetener came from.

In using past-peak fruit, there’s a line between overripe and actually rotten. Apples and pears can be completely brown and translucent, but it’s merely their own ripening process.

very ripe pear

Extremely ripe, but fine

This is the same thing that happens, to a different degree, in the fruit of the medlar (Mespilus germanica), closely related to pears and apples. Medlars are not considered ripe until they are “bletted”, which is the word for this stage of being brown and soft.

You can tell by the smell. If it smells like fruit, even very fruity, it’s OK. Your nose knows. But if it smells like vinegar, or mold, or fermented, it’s gone beyond. And of course don’t use it if you can see actual mold.

pear showing mold

surface mold, truly rotting

If you have overripe fruit trickling in piece by piece, you can collect it in bags in your freezer until you have enough for a batch to cook. You can cut it in quarters so it packs better, and to make sure there are no “worms”, as in homegrown fruit.

Damage, such as worms, induce early ripening, so a worm-stung fruit may originally be only overripe, though the hole can introduce rot which quickly spoils the whole thing. Often, especially in pears, a worm does little damage, causing only a hard lump by the core. The major part of the fruit is fine, though unsightly, and perfect for sauce.

graphic, tree re-work plan


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Shorten cherry trees

A grafting experiment that did not work; to make tall fruit trees short.


In winter of 2019, Arne (I’ll call him), of a local Ecovillage I’ll refer to as “Bamu”, contacted me about some cherry trees. This post is a record of the process. It’s all too easy to never report on failed experiments. But experiments never fail. You always learn something, if only what doesn’t work.

The three cherry trees in question were very tall. They were evidently seedlings, not any improved variety. They bore small, mediocre fruit. They were casting dense shade on other parts of the orchard, suppressing fruit. The community had decided it was time to try to do something about this.

Everybody else Bamu had consulted said, “Just cut ’em down!” I suppose my name came up because I have broader perspective on what you can do with trees.

In the fruit growing country east of the Cascades, orchardists routinely re-work big fruit trees, but in urban Portland this is scarcely heard of. Nobody knows anything but “Cut it down!”

In commercial orchards, this would be a huge economic waste. There is no need to completely remove trees, then plant new trees, then wait years, or decades, till they get to bearing size. Instead, trees are re-worked.

If one variety of, say, apple goes out of fashion, an orchard will “change” all the trees in a block to a more popular kind. Workers go through, cutting off the limbs and grafting the new variety onto the stubs.

This amounts to a rather severe pruning. When the trees grow back out, the new limbs are from the grafts, and therefore bear new fruit. Trees are producing in only a few years.

graphic, re-working a tree

Re-work

This diagram is simplified. In practice, the grafting is done at a particular time of year, not when the host tree has fruit. The illustration is to show the change of fruit variety.

The cutting back can be any degree. One extreme is a great many grafts on all the small branches. This is of course very labor intensive. The other extreme is cutting the tree off, and grafting to the stump. This requires minimal grafts. Orchards generally do the larger limbs, or stump, to control costs.

Orchards are already controlling the size of trees, so the primary reason for re-work is to change the fruit variety. In urban areas, on the other hand, tree size is a major issue. Often, fruit trees have been let to grow for years, with little thought. When they bear, all the fruit is out of reach.

Part of my proposed re-work of the Bamu trees was to control their size. Cherry trees naturally grow very tall, one of the largest fruit trees. The use of “dwarfing” rootstocks is now widespread. Trees grafted on such roots grow only a fraction of standard size.

A variant of that is “interstem”. The tree starts on a sturdy rootstock, not necessarily dwarfing. Then, the dwarfing moiety is grafted on, then the desired variety is grafted onto that. The section of dwarfing stem between the roots and the top causes the whole tree to be dwarfed.

graphic, interstem

Standard, dwarf, and interstem

In the case of the Bamu trees, the roots were what they were. I thought of trying an interstem so that when the trees re-grew, they would fruit at smaller size. Otherwise, varietal cherry grafted on would grow to just as big as before.

The appropriate technique for grafting onto a large cut stem is the bark graft. This video shows exactly how to do it.

I made this video on request from my niece’s husband, Ryan. In the Southeast, where they live, there is a widely planted ornamental, the Callery pear (Pyrus calleryana). Birds spread the small inedible berrylike fruits, and Callery pears come up everywhere.

Ryan had a big Callery tree at the new house they bought, and asked if it could be grafted to edible pears. I couldn’t visit at the time of year to do it myself, so I made the video. Ryan followed the video, and now has ‘Avers’ pear growing on the Callery pear stump.

bark graft

Desirable ‘Ayers’ pear bark-grafted onto Callery pear stump

Pear trees, like cherry trees, want to grow big. Even though Ryan’s pear tree is no longer towering up to the sky, it’s still a challenge to control size. Thus, the idea of the dwarfing interstem on the Bamu cherry trees.

I mapped out a plan where the trees would be cut off to stumps. Then scions of a dwarfing cherry would be bark-grafted on. This would be in the second week of April, the correct time for bark grafting.

These bark-grafted dwarf cherry scions would grow out and serve as the interstem.

graphic, tree re-work plan

Plan to re-work trees

When the interstem had grown sufficiently, varietal cherry would be grafted on. These grafts would be bud grafts, done the second week of July.

So the varietal cherry would be in place within one growing season. Then it would be a matter of re-shaping the trees for productivity.

However, there were other considerations. The community at Bamu had been using the large cherry trunks as hammock supports, and the fire circle there was a social focal point. They wanted to keep the hammocks. Even if the tree tops were gone, they would like the trunks to remain, to build a pavilion.

graphic, other uses

Other uses

The discussion went back and forth. There was the idea of cutting off the trunks higher, perhaps to six feet, or ten feet, and grafting on top there. I pointed out that grafts grow upward, so all the fruit would again be out of reach.

Then came the idea of notching in the bases of the trunks, to “separate” the upper section, and get the bases to behave as cut stumps. I explained this could effectively act as girdling, and the trees might die.

graphic of notches and grafts

Compromise, graft onto notched trunks

Still, with all considerations, we settled on this compromise and decided to try it. At worst, the trees would die, which was no worse than the original “Cut ’em down!” plan. And we would learn something.


On March 20, an arborist topped the cherry trees, and notched them at the base.

notched bases of cherry trees

Notches at base

tall trunks notched at base

Topped trunks of notched trees

On April 11, I bark grafted the trees. I used scions of a rather strongly dwarfing cherry rootstock. Trees on this rootstock can be kept to 15 feet tall.

bark graft

Individual bark graft

On the south tree I put 28 grafts, the middle tree 22, and the north tree 27. This amounted to grafts every few inches around the circumference.

People at the community were interested and curious. “Why so many?” they asked, “Do you need that many grafts?”

line of bark grafts

Bark grafts

I explained that I always like to make lots of grafts, to try and get some kind of statistics. Seldom do all of them grow; and if there are lots, you can get an idea why.

For example, if drying out from strong sun causes them to fail, I would expect to see it more on the south side of the trunks and not on the north. If by some chance they do all grow, you can choose the best.


Arne was proceeding on taking the bark off the upper trunks, but it was slow going. As a concept, it hadn’t seemed too hard, but when it came time to actually do it, working so far off the ground was awkward and strenuous.

Also, the bark was not peeling as readily as I was used to. Bark peels easily, or “slips”, when the cambium cells are actively growing. The trees seemed compromised. The cambium had not become as vigorous as on a healthy tree that time of year.

On April 28, some of the grafts looked promising. People in the community were hopeful the grafts would take. “We’re rooting for them!” Unfortunately, trees have to root for themselves.

bark graft showing some leaves

Bud growth

I was already doubtful the grafts would succeed. I look for vigorous generation of new leaves, not just unfolding of existing ones, as seen here. I thought it was a false start, the scions surviving on stored moisture, and what water could diffuse in from the stock below.

The hammocks were back up, and I could see how much the community loved them. I was a little concerned the grafts might get knocked by activity around them; but, well, there were lots of grafts. It’s always statistics. It would have been a mistake to cut the trees off to the ground. This experiment was worth a try.

By May 24, it was clear the grafts had failed. Arne had not been able to keep up with de-barking the upper trunks. I doubt this would have made much difference.

bark grafts not alive

Failed bark grafts

I noticed the de-barked trunks were wet with sap, to the extent some mold was growing on them. This indicated the roots were still “seeing” the upper trunks as alive, and so the roots were expending their strength to support them.

A check on July 17 showed some growth from above the de-barked area. This was the worst of signs. I meant the work was essentially behaving as a girdle. The tree was continuing to try to keep the top alive, at the expense of further exhausting the roots.

trunk showing shoot growth

Shoot growth above de-barked area

I believe this was the major factor. Minor factors could have been:

  • The initial cutting on the trees was three weeks before time to do the bark grafts. Usually, scions are inserted immediately as the limbs are cut, before the ends can dry back or the plant cells otherwise reorganize.
  • It could have been the time of year. Whereas apples are very reliable to graft in spring, cherries are less so. If this were the major factor, though, at least a few of the grafts should have grown.
  • Normally, after bark grafting, the entire cut end of the limb is sealed over to prevent water loss, and make maximum moisture available to the grafted scions. Here, since the trunk was only notched there was no way to seal over the end.

tall stump

Tall trunks did not live

The cherry trees have died. The Bamu community is going ahead with planning to construct a pavilion, using the dead trunks as support. The formerly shaded sections of the orchards are expected to be more productive.

compact plant


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Bonsai your wax vine

You can “bonsai” a wax vine, for a compact house plant.


Wax vine (Hoya carnosa) makes a good house plant, tolerant of low light and neglectful watering. However, its natural growth form is an extensive vine. If you’ve got room for that, it’s fine.

Here we have one in the bathroom. Notice that it’s also tolerant of being potbound. All that vine, growing out of a small flowerpot.

long wax vine

On bathroom shelf

Of course it would have long since toppled off the shelf, except it’s guyed up by strings. The anchors are those stick-anywhere hooks.

view showing flowers

Side view

The flowers are nice. We would be glad to have more of these plants, but no room for another big vine.

Wax vine is easy to propagate by cuttings. We started a cutting in another small pot.

A wax vine plant grows in spurts. It sits there a long time, gathering strength. Then one day, a vine shoots out. If you let it, it’ll grow six feet or more.

Instead, every time a shoot grew out one node, we pinched off the tip.

shoot with tip pinched off

Shoot pinched after one node of growth

Most plants, If their leaves are not allowed to develop early on, those leaves die. However, wax vine has the ability to keep new leaves small, and then later enlarge them to full size, weeks, months or even years later.

In the picture below, these new leaves are the two small fingerlike structures above and below the pinched-off stem tip.

pinched tip

Pinched tip budding

The part hanging down is the beginning of a flower cluster.

By stopping growth at the pinch, the plant’s strength “builds up” there. Usually, after a time, growth resumes by enlarging the leaves and making flowers. Below is a picture of the flower buds, further along.

partially grown flower buds

Flower buds developing

Finally, they bloom. Don’t pinch off wax vine flower clusters as they fade. The down-curving stalk of the cluster will stay alive. Later, it will make a new flush of buds on the same spur, and bloom again.

wax vine flowers

Flowers

By pinching this way, the whole plant stays most compact.

compact plant

Compact plant

milkweed flowers closeup


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Germinating milkweed seeds

Is there any other flower people plant in their garden hoping the bugs will eat it? To encourage monarch butterflies, many people want to grow the caterpillar host plant, milkweed.

milkweed flower heads

milkweed stalks

I never thought there was anything to it. When I lived in Colorado, a milkweed seed floated into my garden one day, germinated, and set about its usual program of taking over the world.

milkweed spreading through a garden

Yet, here in Portland, many people have told me of failure. “I got the seeds, but they never grew!” So, when some milkweed seeds came into my hands last fall, I decided to see what I could figure out.

ripe milkweed pod, just opening

I was on a garden tour of a native plant nursery. There was a just-ripened pod of showy milkweed (Asclepias speciosa) on the drying stalk. The owner said I could have it. People on the tour were asking how to germinate the seed, and others were clambering “Cold stratify! Cold stratify!”

Now, I have been “cold stratify”-ing seeds since I was a teenager, and think nothing of it. But I have come to realize that for a lot of people, it’s beyond their ken. “Cold stratify” is technically redundant. Stratify means cold, as see this blog.

I had my doubts about milkweed. It’s typically a summer-ripened seed. A lot of summer annuals have a simple germination requirement of dry storage. If the seeds sprouted as soon as they got ripe they wouldn’t have much growing season left, plus, lots of competition from adult plants. So, the seeds have an internal inhibition of germination when they are fresh, which fades over time.

Even though milkweed is perennial rather than annual, I wondered if it might be the same. It sure would be easier if people could forget about stratification! So, this was my hypothesis. That milkweed seeds just needed a period of dry storage to grow. To test it, I would do a series of germination assays, over a period of months, and see what changed.

Cut to the chase. I was wrong. The seeds germinated right away. There was some variation over the months, but probably random. I just put the seeds at about 85°F, and voilà! Milkweed seedlings.

The 85°F temperature was my standard growth chamber, where I was already growing other things. Maybe it was luck.

A good germination test, to be statistically valid, ought to use 100 seeds. My milkweed pod only held about 150 seeds total. So I compromised, and did smaller tests of ten seeds each month (I skipped February). This means the results are more prone to random variation. Still, we learned something.

I germinated the seeds in what I call a “standard germination test setup”, a paper towel rolled around a chopstick, as in this blog. I checked the setup every night, and as soon as a seed put out a root, I planted it in potting soil. Then I later gave the seedlings away.

milkweed seed with root coming out

root can emerge, up to the length of the seed, in one day

milkweed seedling in plug tray

seedling planted

Incidentally, I found I could keep the seedlings in “suspended animation” by putting them in a sunny window in my unheated garage through the winter. They seemed to remain healthy, but stopped their pesky growth! The picture is of three batches started a month apart. Not growing, but unfazed by the cold. What a magnificent weed!

seedlings inside garage window

seedlings in unheated garage, in winter

Below is a chart of the total germination by month. If I’d had enough seeds for good tests, the counts might not have shown any variation at all. Still, germination was never less than 50%.

chart of germination percent by month

total germination by month

The chart of germination speed is even less instructive. Sometimes they started soon, sometimes after a delay. Sometimes they came up quick, sometimes drawn out. But not really over that much variation. Germination usually started the 4th day (rarely 3rd). No more seeds ever germinated after the 12th day.

chart of germination by elapsed days

rates of germination

All too much science never reports negative results. So here I admit, my hypothesis did not pan out. My experiment did not show anything about how to enhance milkweed seed germination. However, it clearly disproves “Cold stratify!”

Now, it is just possible this particular milkweed lost its chill requirement from being in cultivation. This is how it could work. There is always variation in plants. Suppose there were a big batch of wild-collected milkweed seeds, brought into a nursery to grow. Suppose, within those thousands, there were a few freak seeds that did not need any cold period to grow, while all the others did. Those few would be first to sprout. If the nursery person pounced on those, grew them out, and further propagated them, he/she might soon have a strain of milkweed that, genetically, did not need “cold stratify” while wild milkweed does. This is how a lot of crop seeds, such as beans and corn, have evidently lost any wild-type germination inhibition.

If you ever find wild milkweed with enough seeds, you can do your own tests. Cold treat one batch, don’t treat another, and then write your own blog!

Meanwhile, if you just want to get some milkweed growing, try planting your seeds at warm temperatures, and see what you get.

Asclepias speciosa

Here’s my original data, in case you want to check if it was the phase of the moon, or something!

start date count date count
10/6/2019 10/9/2019 1
10/6/2019 10/12/2019 3
10/6/2019 10/13/2019 4
10/6/2019 10/14/2019 5
11/6/2019 11/13/2019 3
11/6/2019 11/14/2019 4
11/6/2019 11/16/2019 6
11/6/2019 11/17/2019 8
12/6/2019 12/11/2019 1
12/6/2019 12/12/2019 3
12/6/2019 12/13/2019 6
1/6/2020 1/10/2020 3
1/6/2020 1/11/2020 6
1/6/2020 1/12/2020 7
1/6/2020 1/13/2020 8
1/6/2020 1/14/2020 9
3/6/2020 3/10/2020 2
3/6/2020 3/11/2020 6
3/6/2020 3/12/2020 7
3/6/2020 3/13/2020 8
4/6/2020 4/10/2020 5
4/6/2020 4/11/2020 9
5/6/2020 5/10/2020 1
5/6/2020 5/11/2020 4
5/6/2020 5/12/2020 5
5/6/2020 5/13/2020 6
5/6/2020 5/14/2020 7
5/6/2020 5/16/2020 9
6/6/2020 6/11/2020 1
6/6/2020 6/12/2020 4
6/6/2020 6/13/2020 6

 

white grit with ruler showing few mm size


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Clean the grit out of sesame seeds

Use water flotation to remove the grit (small rocks) from sesame seeds.


I have been piqued that even high quality sesame seeds contain grit. There’s the disconcerting crunch between my teeth, when eating food made from these sesame seeds. You don’t want to wear out your teeth, chewing rocks! A cracked tooth can cost thousands of dollars to repair. Who needs that?

Cleaning seeds and other agricultural products is a challenge. The only practical way, on commercial scale, is to make use of some difference in properties between the contaminant and the desired material. For seeds, this is typically some combination of sieving and air-blowing.

When you cook a batch of dry beans, you occasionally find a rock or clump of dirt masquerading as one of the beans. it got through the threshing because it was about the same size and weight as a bean. Beans are big enough you can spot the rocks, and pick them out. But sesame seeds are too small.

After trying this a couple of times, I came up with a way, and decided to post this. Here, I use the difference in density. Sesame seeds are oily, and therefore mostly float in water or at least stay suspended. The grit sinks.

Sesame seeds seem to have a life of their own. They are light and slippery, and yet at the same time like to stick to everything. Pouring and spooning them, some always get out and make a mess. So I thought ahead. I was going to have a mass of wet sesame seeds I would need to dry. And dry fairly fast, to prevent mold.

I have a dehydrator. The setup for drying the seeds is one of the dehydrator trays, and a clean bandana.

dehydrator tray and folded bandana

Set up for drying

The bandana goes on top of the tray screen. It serves as a strainer to hold the sesame seeds, while letting water go through. But the cloth is bigger than the tray. The edges would be in the way, when slid into the dehydrator.

bandana draped over dehydrator tray, showing the bandana is bigger

Bandana overlaps tray

So the edges of the cloth are tucked behind the tray screen.

back side of dehydrator tray showing cloth edges folded out of the way

Fold the edges under

The time to get this ready is at the start, before fumbling with a mass of wet sesame seeds.

bandana with edges tucked under dehydrator tray mesh

Edges tucked

Next, the sesame seeds. I did about a 3-cup batch.

3 cups of sesame seeds in a glass quart measure cup

Batch of sesame seeds

I added water to make 4 cups, and stirred a bit.

measure cup and sesame seeds filled to 4 cups with water

Add water to float the seeds

Then I just poured out the floating sesame seeds on the cloth. I also included the sesame seeds that were not clearly floating but only suspended in the water.

pouring water and sesame seeds out of measure cup

Pour out the floating seeds

The grit stays on the bottom.

water and residue in measure cup after pouring off floating seeds

Grit is on the bottom

I spread out the wet sesame seeds and got them drying. The lowest temperature setting is enough, about 90°F.

spreading wet sesame seeds on dehydrator tray

Spread out the wet seeds


The next part is optional, if you want to prove the grit is in that residue. It just looks like more sesame seeds.

sesame seed residue in bottom of measure cup

The dregs

I put the remainder on some metal that could take the heat, in this case, a juice can lid.

residual sesame seeds on can lid

Support to burn

I set up to burn out the remaining organic matter.

propane torch showing how it will burn the residue

Set up to burn

After the water boiled away, the seed oil caught fire.

residuals sesame seeds burning with a flame

Oils burn off

This last part takes a lot of propane, so you might not want to waste the fuel. The charcoal bits have to be red-hot.

propane torch roasting residue

Roast the remainder

The carbon slowly oxidizes away.

glowing carbon burning away

Carbon slowly oxidizes

When the carbon is gone, there are the tell-tale rocks.

grit after burning away carbon

Remaining grit

Sure enough, they are about the size and color of sesame seeds.

white grit with ruler showing few mm size

Measures like sesame seeds.

Meanwhile, the wet sesame seeds are drying. The bandana makes it easy to put them away with minimal mess.

bandana holding dried sesame seeds

Easy pickup


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Persimmon root grafting

Lacking a persimmon rootstock, you can graft a scion directly on a piece of root. Warm temperature is more important than grafting technique.


This spring I gave away a persimmon sapling I had propagated by bud-grafting Fuyu persimmon onto American persimmon seedling rootstock. In the course of digging it out, some root ends got left in the bottom of the hole, Before I filled in the hole, I reached down and grubbed out what roots I could.

I had three healthy pieces of root, and decided to try an experiment, grafting directly on to them. 

Grafting a twig scion onto a section of root is an old technique. It is not so popular in modern times for various reasons.

  • Nowadays, nursery rootstocks are generally available, having stem caliper the right size for grafting to twig-sized scions.
  • Grafting two twigs together (the scion, and the above-ground section of a rootstock whip) is more straightforward, and easier to mass-produce, than fussing with irregular roots.
  • Since the graft is below ground, you have to dig down later to remove the wrapping.
  • It wouldn’t work for dwarfing rootstock unless you either jacked the graft up to expose the top of the root, or were satisfied your stock were going to merely act as a nurse roots till the scion grew its own, and you had essentially rooted a cutting.

Still, it’s useful to know this is an option. Sometimes, rootstocks are hard to come by, and it’s worth the extra fussing. It’s easy to buy rootstocks in quantities of hundreds from commercial nurseries. But if you only need one, nobody wants to deal with you.

I matched the root sections by diameter to dormant persimmon twigs.

I joined them by whip-and-tongue grafts.

I wrapped the unions shrink-fit-tight in black electrical tape, my standard wrap for dormant wood grafting. I did the grafts on March 4.


Grafts heal because a tissue called “callus” grows out of the exposed edges of the cambium, and fills in gaps like hot-melt glue. This is somewhat analogous to the healing of broken bones, where a knot forms at the fracture, and then gradually turns into normal bone.

Easy-to-graft species like apples and pears have callus that grows at winter temperatures. By the time the scion is ready to leaf out, the graft is healed, and so it grows. However, other species are difficult because their callus needs higher temperatures, typically at least 25°C (77°F), to grow. By the time the weather gets warm, the scions have shriveled up and died. This difficult category includes nut trees and persimmons.

The Oregon filbert industry relies on a technique called “hot-callusing” to propagate nursery trees. Filbert scion twigs are grafted on rootstocks in winter, when everything is dormant. The weather is too cold for these grafts to heal on their own, but the hot-callus technique is to lay out these across a heat pipe to keep the graft union warm. Example here.

This is fine for a nursery operation, but a lot to set up for merely a few grafts. You can fake it by keeping the whole graft warm. This is a trade off. The graft union gets the warmth it needs, but the roots can shrivel and the top can start to leaf out and lose moisture.

I did the best with what I had. I put the root ends in damp sawdust to stay moist. I enclosed the whole business in a produce bag to retain moisture.

For warmth, I put the setup in my propagation chamber with the tomato starts, about 27°C (81°F).


I got around to checking the grafts on April 21.

One had completely dried out and died.

One, the graft had died, but the root had put up adventitious shoots.

One, in addition to adventitious shoots, was budding out from the scion.

This shows that persimmon root grafts work, to a certain percent, even with slapdash technique, as long as you keep them warm.

I offered the grafted tree as a giveaway, but did not have any takers. I had no place to grow another persimmon tree, so I let it dry up and die.

 

grape hyacinths in bloom


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Taming grape hyacinths

To keep grape hyacinths from taking over your yard, plant them in a few inches of soil on top of concrete.

grape hyacinths in bloom

Grape hyacinths


Grape hyacinths (Muscari species) are charming spring bulbs. The “grape” in the name presumably refers to their small balloon-like flowers that grow in clusters that resemble upside down bunches of grapes.

detail of flowers

Flower cluster

However, these little plants can be too much of a good thing. Below is a picture of them taking over somebody’s yard.

plants in lawn

Grape hyacinths taking over a lawn.

When I bought my house, there were numerous clumps of grape hyacinth spreading through the garden. When conditions are good, grape hyacinths can multiply rapidly. Below ground, new small bulbs bud off old ones. Above ground, they scatter seeds. Where they become abundant, the soil can be a nearly solid mass of bulbs!

Be careful digging them out. Any scattered dirt can spread them around. I managed to beat them back to manageable numbers by lifting out chunks of soil and literally cooking it in a glass bowl in an old microwave oven.

Now, I enjoy grape hyacinths in moderation. Prevention is better than cure. That means making sure their growing conditions are, well, not so good. It’s helpful to understand the ecology of bulbs.


Our familiar spring garden bulbs evolved to survive through an inhospitable part of the year, usually a dry summer. Also, lack of sunlight for photosynthesis, such as under trees that leaf out and cast a dense shade. During this off season, the entire life of the plant is in the bulb. There are no stems, flowers, leaves or even roots. In this state, bulbs are remarkably resistant to drying out, and to freezing.

tulips blooming

Tulips under a tree that will completely shade them in summer

In the brief time of year when conditions are good, bulbs leap into action. They “spend out their bank account”, rapidly pushing up leaves and flowers. While the good times last, they capture solar energy to create next year’s bulb. As soon as conditions worsen, the plants shut down operations, and retreat back into bulbs. If the overall balance sheet for the year is positive, the plant shows a profit: A bigger bulb than it started with, a few new side bulbs, or some seeds.

This is why you are advised not to trim off the ratty foliage of, say, your tulips and daffodils, after they have bloomed. The plants need those leaves for photosynthesis, to restock their bulbs.

If you have ever “forced” bulbs, such as paperwhite narcissus, or hyacinths, you can see why they are typically treated as a one-time thing. The bulb has enough “bank account” to flower, and make some leaves. But after that, it’s pretty much broke. The conditions to restock are not there. You had the bulb in water, with none of nutrients it would normally get from soil. It’s in your dimly lighted house, where it can’t photosynthesize. If you do stick it out in the ground, the indoor-adapted leaves sunburn and the water-adapted roots struggle to adjust. If the plant does survive, it retreats to a bulb much smaller than the one it started as.

The Pacific Northwest is heaven for bulbs. In our mild winters, they get started early. After they bloom, they have a long, moist springtime to rake in the photosynthetic profit. Many of them open branch offices. A few tulips or daffodils soon become dozens.

It’s not like that everywhere. I lived for ten years in Colorado, where summer slams down hard. Tulips would bloom, then shrivel in the baking heat. Whether they pulled ahead or fell behind would be a matter of microsite. For example, on the north side of a fence, the soil was shaded and stayed a little more moist. In spring, tulips would stay alive long enough to replenish their bulb, plus store up a bit extra. Each year, there would be more blossoms. But on the south side of that same fence, tulips would slowly fail. They dried down early. In a year or two, they stopped blooming, only put up leaves. The leaves got smaller every year. Unless rescued, they would finally die.

Incidentally, here’s a trick to rescue bulbs, or just move them when they are in the best stage to move, namely completely dormant. Maybe you think you’ll remember where they are. But lo! Those lush blooms and foliage disappear without a trace. It’s midsummer, and the ground is hard and dry. Maybe you poke around with a trowel, and occasionally stab one of the bulbs, and cut it in two. How can they hide so well? Next spring, there they are back again, blooming. But at that stage, it is very stressful on them to be moved.

crocuses with marker

Crocuses marked for moving

Here’s the trick. When the bulbs are blooming, slip a bamboo skewer down beside each stem. A package of 100 costs only a few dollars. If you accidentally poke into a bulb, it does little harm. Then, just wait for summer. The skewers look significantly different from anything else likely to be in your garden that time of year. The ground is dry. Just tunnel down by each skewer, and there is your bulb. If you want to sort out different kinds of bulbs, make up a barcode, and mark each skewer with a grease pencil (all other kinds of ink fade away). Say, one band means yellow, two means purple, and so on.

Different kinds of bulbs are more and less aggressive, and grape hyacinths are the toughest ones I know. Take note: Grape hyacinths start pushing up new leaves after the first rains of late summer. So, they are in business months before anybody else! No wonder they multiply like mad.

grape hyacinth leaves

Growing after a single summer rain

So here’s the method to control them. Put a few inches of soil on top of bare concrete. Use the worst soil you have. Plant grape hyacinth bulbs in that.

planting diagram

Plant bulbs in only a few inches of soil

In the winter rains, the bulbs will grow. In spring they will bloom.

plants flowering in the spring

Plants flower in the spring

But as soon as the rains slack off, the season’s over. The minimal soil dries out, and the plants go dormant. They do not get to spend the long luxurious spring months drawing moisture from the subsoil, to increase themselves, and bud off side buds and make seeds.

bulbs going dormant

Bulbs go dormant when rains end

They just about break even. They will sleep all summer, and be back next spring.

Here’s an actual planting done this way. The concrete steps run right over to the adjacent concrete foundation. There is no other soil. (This photo is from late March.)

bulbs planted on steps

Planting, on concrete steps

The large straplike leaves mixed in are tulips. The tulips produce leaves every year, but have not been able to make enough headway to bloom.

In May, as things dry out, the grape hyacinth plants are packing away everything they have into their bulbs. They do not have the resources to even try making many seeds. In the photo below, notice how few pods there are. Some of these are not even filled. If the stalks do manage to ripen a few seeds, they are stranded out on the concrete, not likely to fall any place they can grow.

grape hyacinth pods

Pods are sparse

A similar method, using the same principle, is to confine grape hyacinths to pots. These look pretty good when in full bloom. They fill out, and don’t even look like potted plants.

plants in a pot

Showy blooms

Put they are entirely in pots.

blooming plants in a pot

Entirely in a pot

I have a line of these pots set, again, on top of concrete, up under an overhanging eve. They get only the rain that drifts in on them during the winter. They provide some welcome spring color, then die back and disappear for the rest of the year.

They start growing as early as September. These started after an anomalous August rain.

sprouts in a pot

Grape hyacinths sprouting after a single summer rain


There are some other flowers I treat in a similar way. I grow them where they can barely survive.

This is Kenilworth ivy (Cymbalaria muralis).

Kenilworth ivy plants

Kenilworth ivy

Here, I have it on a mossy concrete block in the midst of, you guessed it, an expanse of concrete. It gets a little drip irrigation overspray during the summer, but not much. This plant is so invasive, I don’t let it get anywhere near topsoil! Even this little patch of it, I come along periodically and rip half of it out.

This is the annual forget-me-not (Myosotis sylvatica).

forget-me-not plants

Forget-me-not

Yes, they have pretty blue flowers in the spring, but each plant can make thousands of seeds. Here, I’m letting it root where it can, in chinks at the base of a concrete block wall. These blocks are not on the soil, but on top of (somewhat dirty) outdoor carpet. The plants manage to snake their roots down enough to grow and bloom. But they die when the weather turns dry. Even so, they still make more than I want, and I weed out the extras,