Cedar elm, Ulmus crassifolia, is one of the very best species for bonsai and especially for beginners. They are “sturdy” trees, not being bothered by much in the way of pests and diseases. They’ll take a good bit of abuse and neglect without objection. They grow fast which allows for rapid development. And they put on a nice rough bark at a fairly young age.
This past April I made a trip to Cedar elm country, having been invited by an old and dear bonsai friend to collect some specimens from his parents’ property. To be sure, a January trip would have been better suited to lifting these trees, but it just couldn’t happen till April. I figured that if any species could stand up to being collected out of season, Cedar elm would be one of them. So I jumped at the chance.
A week after I’d gotten the trees home and potted up, they were all showing buds. I’d collected just under 20, including a handful of larger ones, a handful of smaller ones and a handful of in-betweens.
Now, I’m generally leery of trees that pop buds a week after being collected, but there wasn’t anything to do about it so I just waited and watched. Within four or five weeks, all of them had put on shoots ranging from an inch or so up to about six inches long. I was encouraged, but I knew not to get too far ahead of myself. And sure enough, they all stopped pushing new buds.
This is an important phenomenon to understand when you collect deciduous trees. Usually you won’t have any fine roots on a tree collected from the wild. This is all right – in fact, I’m convinced after 30 years doing it that it’s not even desirable.
Within a couple of weeks after collection or at budburst in spring if you collect in the dead of winter, your tree will produce trunk buds from stored food. These buds will grow into shoots that will push anywhere from a few inches up to perhaps a foot in length. At this point most species will pause their growth, and this pause is for a very important reason: it’s time for the tree to make new roots. This is absolutely the critical point in the collecting process. The tree has expended all of its stored energy making foliage to produce food plus, equally importantly, the hormone auxin which stimulates adventitious root growth. If this process succeeds, new roots are made. If it fails, the tree dies.
This is one of the in-between size Cedar elms I collected. Nice trunk with some good character and starting to bark up. As with the others, it pushed new growth over the first four or five weeks on the bench. Then it stopped growing, as the others had. It just sat there for at least a week or two, and did nothing. Then one day when I was checking on things I noticed some tender new growth starting up.
Here’s the tree today. I photographed it from this angle in order to show you one of the key ways you can gauge your success with certain collected species. Notice the color of the growing tips?
When you get strong growth on certain species, and Cedar elm is one of them, the growing tips produce a considerable amount of anthocyanins along with chlorophyll.
Anthocyanins are what give you the red and purple colors of fall foliage, and they play an antioxidant role in both foliage and fruit (think bluberries, cherries, etc.). This may be why the plant produces more anthocyanins when it’s recovering from collection, but I’m not certain. One thing I do know, it’s a way to gauge the success of your collecting effort with Cedar elm.
The initial shoots I got were just green; they were produced by stored food. When the second round kicked in, I got the reddish color, larger leaves and stronger shoots. I knew the tree was growing roots at this point.
Unsurprisingly, the smallest trees I collected produced roots first. I’d potted two sets of three each, with the idea of making group plantings out of them. Here’s one of the sets. Nice variation of trunk size, nice trunk movement, nice taper, and the beginnings of bark.
First a trim. It’s likely I’ll have to remove some root in order to get the group into a pot, so taking off some foliage will maintain the balance. Looking at these trees, can you tell which is the main tree and where the others need to go?
Notice that I’ve wired the three trunks together near the bottom to keep them stable while the roots grow together. This is a trick you’ll need to employ sooner or later.
I plan to post this group planting for sale in a few weeks, assuming I didn’t cause any trouble today. Given the good root development, I’m confident these trees will respond very well to their new home.
I’d love to hear what you think about this bonsai-to-be.