2021 5 year native tree challenge. Bonsaidoorguy's Black Cottonwood.

Bonsaidoorguy

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20210106_161422.jpgI collected a couple of these guys and this one has a clump style coming from a decent base. Sorry for the crappy picture but it's rooted through it's grow box and I want to leave it till spring.
 

MaciekA

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Jumping on this thread as a watcher and a fellow black cottonwood fan hoping to compare notes. I collected some cottonwood from the Cascades at about 5000ft elevation back in 2019, and have decent recovery now. The area I collected from was loose roadside gravel on a decommissioned/unused forest road (w/ roadside collection permit).

It seems that black cottonwood is very durable. I've seen it at creeksides in the high desert, next to farms near John Day, in the Coastal range, and near my house in the Willamette Valley, which is an impressive range of climate tolerance. During the great 2021 PNW heat wave, I didn't encounter any signs of problems in my collected cottonwood, and while I shaded it during the heat wave, it is typically sat next to my pines in the sunny area, and not next to my maples. I find that its growth and health improved after moving it to a sunnier location. It consumes water very fast. I have it in mostly pumice in an old cat litter box (w/ swiss-cheesed bottom), top dressed with moss (which really helps with keeping up with the thirsty nature).

Foliage has multiple forms, I haven't studied the botany of this but informally, there is one form that emerges from spring buds usually in groups of 5 (I've been assuming it's mature form), then there are more elongated presumably-juvenile leaves that emerge after that. There's one third form that I think of as the goofy-vigor form, which is a larger and wobbly-shaped version of the juvenile form, coming out when the tree is really happy and weather is hot.

I have found that cuttings taken from my collected cottonwood are able to survive in water / wet spaghnum for weeks, and will readily root. An arm-length cutting taken from my collected tree about a month ago is still alive, having initially sat in water, then in moist sphagnum. I didn't expect it to survive the heat wave, but it did. I left it outside in shade. It lost many leaves, but after shedding those, has resumed growing with a handful of remaining functioning leaves.

The cottonwood I collected in 2019 had borers. Be on the lookout for that sort of thing. A single dose of imidacloprid knocked them out.

I had a poor recovery location for this tree in 2020, with too much shade and too large a recovery soil volume (due to the akward trunk-root setup dictating container choice somewhat). It didn't like that and had some kind of sparsely-distributed foliar disease (big fungal-looking brown/yellow spots) that I never diagnosed. By the end of 2020 it had developed many arm-length suckers with very large foliage, and I kept fertilization pretty high to prep it for a repot in spring 2021. It hasn't had any sign of any kind of disease this year after repotting into pumice and going into full sun, where I'll keep it indefinitely.

I did a test wiring this year after the first flush hardened to see how it takes to wiring. Two vigorous branches with plenty of juvenile leaves took well to being wired at that time, and recovered fully from an accidental kink-bend. Somewhat more mature apical branches with only mature leaves didn't recover as quickly or as well.

I pruned away several of the super-vigorous arm-length sucker branches (one of which became the immortal cutting mentioned above) a few weeks ago as it became obvious they were winning out over the branches I have on the trunk.

From what I've seen on this tree and one other like it, it will be very important to establish exceptionally strong branches and somehow over time minimize wounding of more mature pieces. Cottonwood seems to be a rot-happy, hollow-happy species.
 

Bonsaidoorguy

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Jumping on this thread as a watcher and a fellow black cottonwood fan hoping to compare notes. I collected some cottonwood from the Cascades at about 5000ft elevation back in 2019, and have decent recovery now. The area I collected from was loose roadside gravel on a decommissioned/unused forest road (w/ roadside collection permit).

It seems that black cottonwood is very durable. I've seen it at creeksides in the high desert, next to farms near John Day, in the Coastal range, and near my house in the Willamette Valley, which is an impressive range of climate tolerance. During the great 2021 PNW heat wave, I didn't encounter any signs of problems in my collected cottonwood, and while I shaded it during the heat wave, it is typically sat next to my pines in the sunny area, and not next to my maples. I find that its growth and health improved after moving it to a sunnier location. It consumes water very fast. I have it in mostly pumice in an old cat litter box (w/ swiss-cheesed bottom), top dressed with moss (which really helps with keeping up with the thirsty nature).

Foliage has multiple forms, I haven't studied the botany of this but informally, there is one form that emerges from spring buds usually in groups of 5 (I've been assuming it's mature form), then there are more elongated presumably-juvenile leaves that emerge after that. There's one third form that I think of as the goofy-vigor form, which is a larger and wobbly-shaped version of the juvenile form, coming out when the tree is really happy and weather is hot.

I have found that cuttings taken from my collected cottonwood are able to survive in water / wet spaghnum for weeks, and will readily root. An arm-length cutting taken from my collected tree about a month ago is still alive, having initially sat in water, then in moist sphagnum. I didn't expect it to survive the heat wave, but it did. I left it outside in shade. It lost many leaves, but after shedding those, has resumed growing with a handful of remaining functioning leaves.

The cottonwood I collected in 2019 had borers. Be on the lookout for that sort of thing. A single dose of imidacloprid knocked them out.

I had a poor recovery location for this tree in 2020, with too much shade and too large a recovery soil volume (due to the akward trunk-root setup dictating container choice somewhat). It didn't like that and had some kind of sparsely-distributed foliar disease (big fungal-looking brown/yellow spots) that I never diagnosed. By the end of 2020 it had developed many arm-length suckers with very large foliage, and I kept fertilization pretty high to prep it for a repot in spring 2021. It hasn't had any sign of any kind of disease this year after repotting into pumice and going into full sun, where I'll keep it indefinitely.

I did a test wiring this year after the first flush hardened to see how it takes to wiring. Two vigorous branches with plenty of juvenile leaves took well to being wired at that time, and recovered fully from an accidental kink-bend. Somewhat more mature apical branches with only mature leaves didn't recover as quickly or as well.

I pruned away several of the super-vigorous arm-length sucker branches (one of which became the immortal cutting mentioned above) a few weeks ago as it became obvious they were winning out over the branches I have on the trunk.

From what I've seen on this tree and one other like it, it will be very important to establish exceptionally strong branches and somehow over time minimize wounding of more mature pieces. Cottonwood seems to be a rot-happy, hollow-happy species.
Well what I've observed is that they are very vigorous growers and you shouldn't hesitate to cut to decrease the size, they just sprout side branches. I transplanted into this training pot to get the roots good and shallow. I guess this is my summer update. I've seen some cottonwood haters here but I'm having fun with this tree. Still going for a multi trunk/clump style. Only clip and grow for now, I hate wiring deciduous trees. I always miss cutting it off in time and then I end up with scaring that will take years if ever to go away. I've used guy wires also but the style I'm going for should work well with clip and grow.20210701_172213.jpg
 

Bonsaidoorguy

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Early summer update. Going well, working on reducing the height a little. IMG_20220710_143730703~2.jpgIMG_20220710_143816161~2.jpg
 

Bonsaidoorguy

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Mid summer update, this is a fun tree to work with. Leaf size is getting smaller and lots of good growth. I need to start looking for a slab of some kind to put It on.IMG_20220803_110425125_HDR~2.jpgIMG_20220803_110439390_HDR~2.jpg
 

MaciekA

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Looking very nice. How did you do with watering in the last couple weeks ? Mine has been outageously thirsty and I look forward to putting it into akadama and a shallower pot next year.

Cottonwood in an anderson flat sized container with coarse pumice in warm sunny environment is something I'd no longer recommend if you don't want to be chained to your hose every day in the summer :)
 

MaciekA

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Also, I wanted to add that I tested partial defoliation this year (under the guidance of Andrew Robson, otherwise I'd have still been hesitant for a while). What he recommended, and what I did:

- Left the apical leader, shoots on it, and leaves on it untouched.
- Cut all other shoots back to 2
- Halved the size of all the leaves on the cutback shoots
- Left it alone since

The result is that cottonwood responds well to partial defoliation and cutback. If I had more large cottonwoods on hand, I would be tempted to try full defoliation, as the response growth was very aggressive. Most of the growth after partial defoliation + cutback was out of the bud closest to the cut tip, though some of the response growth was one node back from that.

This was done on June 12th 2022. Most of the response growth that grew out of the buds at the cuts has put on either 12 or 13 internodes each since then. I also have a one year old cutting which I bare rooted into a colander this spring, and which doesn't have a great trunk, so I decided to experiment and see what the response to partial defoliation and cutback would be on a 1 year cottonwood cutting: Also very aggressive.

As you recommended above:

you shouldn't hesitate

Can confirm! Don't hesitate. Cottonwood bonsai is sport bonsai.
 

Bonsaidoorguy

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Looking very nice. How did you do with watering in the last couple weeks ? Mine has been outageously thirsty and I look forward to putting it into akadama and a shallower pot next year.

Cottonwood in an anderson flat sized container with coarse pumice in warm sunny environment is something I'd no longer recommend if you don't want to be chained to your hose every day in the summer :)
Thanks, I'm older and have no social life so it hasn't been too bad, just watering daily and fertilizing weekly. I also have a shaded area under some trees which is where this guy sits.
 

MaciekA

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Hey @Bonsaidoorguy , hope you and your cottonwood are doing well. Back at the end of October, I wired and cut back mine, here's a link to some pics:


It still has some large sacrificial growth up top and is still in a large grow box (formerly a kitty litter). Andrew Robson got me into an "embrace the rot" mood with this tree, so I may be solving the leftover stump issue by carving out a hollow of some kind.

Back in June, I took about 50 cuttings of cottonwood from a single tree in the ravine below my house, stuck them in a bucket, and almost all of them rooted. In the new year, I'm hoping to assemble a forest (or maybe some forests). I like the look of your cottonwood composition, this species looks beautiful when seen in a big group all changing color at the same time, I'm hoping to build something like that!
 

Bonsaidoorguy

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Cut it back a little more this year and it didn't seem to mind. Spring update picture.IMG_20230526_165753758_HDR~2.jpgIMG_20230526_165816138_HDR~2.jpg
 

Bonsaidoorguy

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Just gave it a trim so I thought I'd post an update picture. I think it's looking pretty good this year. I'm trying to keep it a little shorter.IMG_20230729_105224363_HDR~2.jpg
 

Bonsaidoorguy

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Fall pics. I actually like this time of year.
 

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