Bonsai From the Ground Up

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For quite awhile now my wife and I have been searching for a new home. Unfortunately, the search is not over yet, but it became imperative that I dig up and pot all of the trees that I have been growing in the ground for a good ten years now. This movement from ground to pot actually started several years ago with a Styrax and a few Crabapples. Now that the process has been accelerated by the impending move, the experience has been quite enlightening. I thought that it would be a great time to share some of the triumphs and travails while they are fresh in my mind. I have had a few requests to talk about growing trees in the ground, so, here ya go.

First of all, growing bonsai from scratch is a privilege. Living in this great country where you can own a piece of land, however small, and a great state like Oregon where trees grow like weeds is awesome. My bonsai hobby (if you can still call it that) started out on an apartment balcony in Lake Grove. A pretty small space, but I had it good. I was on a second story slab of concrete where bugs and birds were a minor concern and security was impeccable - ever try scaling T-111 siding?  

But within a few years I had outgrown the space and bonsai was the main reason to leave the ease of an apartment and actually buy a home. The point that I am trying to make is that growing in the ground is not a possibility for everyone. Even at my first house, which had a third of an acre, I didn’t grow any bonsai in the ground. Wasted time and space.  

Then, shortly after I moved into the current home, I did the darndest thing and went to study bonsai with Boon Manakitivipart. Through Boon I learned to appreciate deciduous bonsai much more. So much that I began to increase my collection of those wonderful trees. That’s about the time that importation of trees from Japan began to be curtailed and sources for great material were drying up. I realized that the only way that I was going to have any good deciduous trees would be to grow them myself. Now I want to stop and state right here that NOTHING beats the quality of growing trees in pots. The control that you have on shape, health, roots, trunks, branches, etc… is superior. But you can also do a fantastic job scrubbing your bathroom floor with a toothbrush. It is all a matter of time and perspective. I wanted to halve my time and was willing to sacrifice some of that control, especially since I was after larger trees.  

It was about this same time that I discovered Oregon Bonsai and Randy Knight. Randy had been growing trees on a very large scale and I was permitted to purchase and dig a few from his field. He had started out growing his trees on ceramic tiles, which worked very well at creating a flat root pad. This was my first experience dealing with field grown trees. But as most of you know, I like bigger trees, so after my acquisitions were dug, cleaned, top pruned and root pruned, they went straight back into the ground. There were several crabapples and some quince.  

I built some raised growing beds into the gentle slope of my back yard and away we went.  

Over the years, I added to that initial planting from several sources. I planted trees that had been developed in pots for several years with nice spreading root bases, and I also purchased regular landscape material in one to five gallon pots. Some were collected from other yards and there were even volunteers that I just started training into bonsai. I added many different species, including: several magnolias, crepe myrtles, beeches, stewartias, Japanese maples, beautyberries, cherries, sweetgums, alders, native crabapples, Indian plum, etc…. As you can see by the list, most of these would really be hard to come by. I didn’t grow any conifers. It is way too easy, albeit, expensive, to obtain hundred-year old specimens than to try and grow them myself.  

From the start I knew that the goal was to grow trunks and I didn’t really care about branching in particular. I was after volume. And I knew that to do that I must really let things grow. By the way, this runs true, whether you are growing shohin or huge behemoths.  

Every year I identified a leader for that year’s growth – the direction that I wanted the trunk to grow. Sometimes I would even wire up a branch into position, or just raise it with a rebar stake and a piece of wire. Using the later method, it didn’t matter if the wire cut in, because I was tying up high, into the part of the tree would never be used in the final product. Applying wire while the tree is in the ground is difficult, and invariably it will start cutting into the tree because it is growing so fast. But it was necessary to get new leaders in some cases.  

The trees that I had the most success with were ones that already had some shape going into the ground that I could build on. Material with nicely compact and sinuous curves and gentle movement. But you have to be sure to scale your movement to the final size of the tree. Side to side movement of a few inches that seems drastic when the tree is a half-inch in diameter is almost totally gone when the tree reaches 4 inches in diameter. There are no bonsai that look good with a 6 inch straight section. This is really common with trees purchased from landscaping stock. We need curves. Better to bite the bullet and make whatever cut is necessary and let it regrow. This is much easier and palatable in the ground. Most of my pruning occurred in late winter and early spring where I could really evaluate what was going on.  

Secondary pruning, especially when I needed back budding took place at various times in the growing season. May would always be my best bet for cutting back.  

The trees put on incredible growth. Some species could add 6-8 feet a year to their height. At most, I let them grow two years without cutting them back. The first year of free growth they would really put on height, but that second year, they really thickened up, with many side branches. Many simply grew too fast and I had to whack them every year – that would be the alders. Boy, can they grow fast. In contrast, the stewartias and styrax grew fairly slowly, both in height and girth.  

Every time that I pruned the trunk I used cut paste on the wounds. I found that it always has worked the best for my cuts. I also found that some trees heal over very easily and some do not, even in the ground. So I came up with my general rule that any sacrifice branch can grow to a maximum of half an inch diameter before I need to cut it off. I was after quality and anything bigger than that left too big of a scar to heal. The crabapples growing in the ground simply would not heal large wounds for me, but the slow growing stewartias and crepe myrtles healed over magically. So you always have to know your species.  

The great advantage to growing in the ground is that there doesn’t have to be a dormant season during the summer. I made sure that the ground stayed moist even during hot spells andfound that trees could power right through the heat. I tossed my old fertilizer from the pots onto the growing beds and added other fertilizer as supplements and got some astounding growth.  

The trees went into the ground at various times of the year, in different years, and in different sizes, so not much consistency there. At first, I think, I dug up some of the trees after a year or two, then root pruned and replanted them, using 12 inch ceramic tiles under each, or sometimes plywood. As I mentioned earlier, I had already started to dig some of my treasure and put them into pots several years ago, and even sold a few. Knowing of my impending move, I went through all of them last year and used a shovel to cut a ring around them in the ground, to prune the roots and get them ready for this year’s Herculean task. I even had to take an axe to the alders, since the roots were well over an inch in diameter. I also dug up several trees and moved them to make room for others. Plus, I dug the two crepe myrtles, which I had planted in the front yard to enjoy, and moved them to the growing beds. But they too, were always destined for bonsai glory, so they had been planted in the front yard WITH the requisite tiles under them. It worked well, because they had not grown much due to too much shade.  

So the Forsythia that I had moved last year and dug first this spring came up with a massive base and a very nice root pad. Sweet success. But then I began to dig the trees that had been in the ground longer. The ones that I had supposedly root pruned several times with a shovel over the years. With the trees growing on tiles, I got some surprises. The tile always did its job and developed flat root systems. But sometimes the roots would grow over the edge of the tile, then down (That’s a good reason to use a big tile) or they were just planted overall too deep and I got more roots than I thought that I would. But at this point, I still highly recommend it. But I found that more often than not, I hadn’t actually gotten a tile under the tree. More than that, the shovel had either failed to prune the roots, because my ringing diameter was too large – not really likely, or the roots simply headed for China. The result were root pads that sometimes resembled giant squid with long root tentacles hanging down. That means that I had to cut all of those off to get them into a pot. Mostly it meant a lot of hard work. So remember when I said it was my intention to dig them up every two years to root prune them? It obviously did not happen. I sometimes ended up with roots almost two inches in diameter and totally useless for bonsai. The one really great thing is that they were all very strong and vigorous. After all the hacking, digging, and cutting back, they all seem to be making it. You will be able to see some of the results on native trees at this month’s program.  

So here are some observations and sort of a checklist of lessons learned.   
1.    Ground growing requires just as much attention as growing in pots. For great results, you still have to water, prune, monitor, etc...
2.    Growing in the ground is for developing trunks only. You might be able to use some of the branches later, but don’t count on it if you are going for size.
3.    You can grow too fast. You must create movement in the trunk, either through successive pruning, or wiring, or starting with a pre-developed shape. And this movement must have the final size in mind.
4.    You must know your species, just as if you were growing in a pot. Know how it will react to pruning, how it will back bud, and how it will heal scars.  
5.    You must prune the roots at least every two-three years. Otherwise, you are creating bulk that will just be a problem and you are not making the shallow root pad you would like. You really need to keep encouraging the division of roots in to many fine ones instead of thick and heavy ones.
6.    Watering is still critical. Planting on tiles means that the roots must go sideways to find water and more resources. It also means that the tree is less stable until it dives over the edge of the tile.
7.    Letting trees grow wild means that they need more room. Mine got really crowded and started to shade each other with their 6 foot tops. That meant that interior branches started to fade, so I had to prune trees earlier than planned.
8.    Prune hard early in May so that trees can re-grow before the heat of July and August, or branches and trunks may burn.