In ground root pruning

[digger714]

I have some japanese maples, some ginko biloba, and some seiju elms that i have had in the ground since last spring. They have several years left to develop, but am trying to learn more about what to do to them while in the ground. I guess as long as there are not two branches coming out from the same point in the trunk, that will keep any bulges from developing. I would think that most branches i have now would be too large for the finished tree once the trunk gets to the size im wanting, so im sure new branches would have to be grown. I like the idea of cutting around the rootball with a spade shovel every year or two to get the roots developing closer to the trunk. What time of year would be the best time for this? And, should it be done every year, or every other for the most benefits? THanks for any help, or other ideas for growing in ground.

 

[Bill S]

Many when put back into the ground do not respond very quickly, and take 2 to 3 years before they are really active in growth, they are in the ground to grow size, you don't really want to keep insulting them until you get close to what you are looking for. Unfortunatly putting them in the ground to grow, you give yourself a new root training period after the new growth. This is a case I believe where you can't have your cake and eat it too.

 

[digger714]

That makes perfect sense. I can tell that they have doubled in size this year, compared to last when they hardly grew at all on top. I guess they were getting their roots going the first year, and getting settled into their new home, then the next few years should do alot more top growth. So, when it is time to start thinking about developing new fiberous roots close to the trunk, when would be the best time of year? Am i thinking correct in that you grow the trees until the trunk is the size you want, then start looking at developing better nebari, or is there anything that should be done during the trunk development that would help the nebari? Thanks for the input.

 

[Bill S]

After the roots regain vigor and start to grow the tree again, and you are happy with the trunk size, you are collecting it again, the spading around the tree ( best during the trees active root growth period) is what helps with collecting it with the most smaller feeder roots. Remember though, the collecting process will slow it down again, until your potted up root mass settles into pot cultivation again.

 

[Eric Schrader]

As in anything, there are many ways of being successful in growing trees in the ground. Raw speed of trunk fattening is not the only consideration. I use boards, with the tree screwed from below using a stainless steel screw, the boards rot after about 4-5 years, but I put bonsai soil on top of the board and put the board on top of regular field soil. Keeping the tree properly watered allows fine roots to develop near the trunk at the same time that larger roots are going deep into the soil to make the tree fatten. Each winter I clear away the soil carefully and root prune some of the largest roots - this improves the nebari and the branching of the root system. I don't just spade them, I carefully select the larger roots and cut them while not cutting the smaller roots.

 

[Bill S]

Interesting approach Eric, any issues with having to be carefull re. water, I would think the bonsai soil would dry quicker than the surrounding soil, so counting on rain would be iffy to maintain the tree. I would think you would have to keep an eye on these and water accordingly even though planted, more so anyway than your landscape plantings? At least untill there are some escaped roots outside of the looser soil. Like the idea of easy top removal of the soil to work under the hood so to speak.

 

[Eric Schrader]

The trees require either a watering system or regular watering by hand to maintain the small roots near the trunk. I've pulled all my trees that I had in the ground because I just moved, but this winter I will be starting again (with many of the same trees going back into the ground.) While in my yard in San Francisco I kept a layer of mulch over the top of the bonsai soil and I watered 1-2 times per week depending on the weather. Now that I'm in SoCal and it's much hotter I'm expecting that I will set up a watering system to provide drip irrigation to the plants in the ground. I've lived my whole life in CA so irrigation is the norm for most of the year, not the exception.

But watering is not the only thing that I do while the trees are in the ground - I also wire and prune them to improve the shape and move the tree along. I've found that if you wire a cutting or seedling before you put it in the ground and then just forget about it you get a small section at the base of your tree that has movement and a big chop, but if you take more time while it's in the ground to wire and plan where the cuts will be then you end up with a better tree for your years of waiting.