What is your goal? Why did you return them to the ground? Health? To gain trunk caliper?

It's helpful to periodically lift & turn trees planted in the ground to promote even growth. The occasional root pruning while in the ground makes it easier to lift and get the tree into a pot when it's time, but you need to balance that against the fact that lifting/pruning slows growth. Type of tree also weighs heavily in the decision. Some trees, you can do practically anything you want to and they recover quickly, others are more sensitive & take longer to get back on track after root work, so I guess you're left with a big 'it depends ....'.

Al

I put them in the ground to gain trunk size. 4 of the 5 trees are maples and one elm. I know the trees and know what the can handle as far as pruning and what time of year they like to have it done. This is the first time i've ever put a bonsai in the ground and im just a little concerned about getting them back out. I have read countless articles about "field growing" and it is something that most specimen trees have experienced at least once in there life. Im just wondering if they should be lifted anually or bi-anually to be root pruned.

When field growing you don't actually 'lift' the tree and root prune, it's left in the ground. Normally you would prune, wire and do whatever you need to while the tree is activly growing in the ground, you don't mess with the roots until a year or two before you want to harvest it.

At that time you pre-dig early, the season before by taking a good sharp tree spade and cut the roots inside the drip line of the tree, all the way around. Let it sit and the roots will develop fine hair roots where they were cut. The following spring will be the time to lift the tree and harvest it for a pot.

You would dig it again but just outside of where you cut the roots the first time.

Bob

Thanks Bob that is exactly what i needed to know.

I think whether or not it's appropriate to lift trees and work on roots depends on your goals, and needs qualifying. If you're into production and only want the trunks to fatten quickly, by all means, leave them in the ground and don't concern yourself with the roots or branch distribution/balance - let the next guy worry about that, but if you want a quality tree with balanced branch placement and even roots, lifting and rotating your trees on a regular basis (usually every 2 years for mine) will give you the most even branch and root distribution. Regularly pruning roots when you lift the tree to rotate also promotes a flat root system that is easy to transition into a pot.

The reason we're forever being reminded to rotate our trees in pots is so all sides of the tree get equal amounts of sun. NOT rotating our trees in pots gives us one-sided trees - both roots and branches, and the farther north or south you live, the more pronounced this effect is.

The relationship between roots and branches varies by genus/species. In some trees (Thuja, e.g.) it's almost as though individual roots carry nutrients to individual branches, and the same branch provides the root with it's food. Sever either the root or the branch, and the other partner in the relationship is almost certain to die back. In other trees, the relationship may not be quite so devoted, but we KNOW this occurs to some degree in all trees.

The reason I mentioned this is because with trees that are not rotated, the same branches continually get the most light and grow strongest, while the opposite side remains weaker and thinner. The strong branches 'feed' the roots on the strong side so they develop much faster than the roots being fed by weak side branches. The result is a lopsided tree - top AND bottom.

As I look at this equation, I think the qualifying questions we need to ask ourselves are: Am I interested only in growing the fattest trunk as quickly as possible, or do I want to deal with the fact that it might take a year or two longer if I rotate the trunk in order to build a quality tree? Do I want to take a little extra time and develop a balanced tree with roots ready to make the transition into a bonsai pot, or do I want to hurry up and get that fat trunk, only to struggle getting the tree into the pot, and then spend more years than I saved rebuilding the root and branch structure?

I always lift and rotate the material I'm growing on for bonsai for the reasons I mentioned. I end up with even branch distribution, branch diameters and a strong, even root system.

Here is the trunk/nebari of a Styrax japonica I grew from a cutting, using the lift/root-prune/rotate method I just described, just after I lifted it in spring 09. It's typical of the trees I pull out of the ground.

So, if you just want a tree with a fat trunk you can pass on to the next guy so he can worry about what to do with it - plant it and forget it, but if you want a quality tree, you need to do what's necessary to 'bring it along'. It's tempting to think that because it only took 2-3 years to fatten a trunk instead of 4-5, that you've saved a lot of time; but, how much time have you really saved if it takes you 4-5 years to straighten out the root and branch problems, as opposed to 2-3. What does your logical side say about which is the more favorable route to a quality tree?

Al

Oops - HERE .... is the trunk/nebari I mentioned:

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Al

Holy $#@!, Al!

I never even considered lifting and *rotating* trees in-ground!
That's been my main reason for not growing in-ground...lack of ability to rotate the plant.

Josh

Al,

I want a well balanced tree, the trunk will thicken in time. I plan to leave to the trees in the ground for as long as it takes to get a great end result. I was planning to rotate the trees and root prune every other year. When the trees were in a pot i would rotate the pot 1/4 turn every 7 days. Now that they are in the ground how should i rotate them? If i continue a 1/4 turn every 2 years it takes 8 years for a full rotation just wanted to know how your rotating yours.

If you're more interested in balancing the light and good nebari, you could leave your trees in pots, mulched into larger containers and still be outside, but with portability and ease of turning them. That's what training, or grow boxes are about - a sort of compromise between 'bonsai' pots that don't allow much development at all and being in the ground. Because in the end if you root pruning every two years(?) will very much slow growth and you could do better if something like large collanders were used.

A large training box won't put on the growth the plant will show in the ground, even in consideration of the practice of lifting it periodically to keep the roots in good shape. I think much of it has to do with more favorable root temperatures and moderation of the cyclic death and regeneration of roots that is exaggerated in container culture. Of course, they have their place, and will produce trees even more refined than those grown in the ground and lifted/rotated - it will just take longer.

Taking it a step further, simply growing the trees in bonsai pots as they develop will produce the most highly refined trees, but it will take the longest.

Al

So i could grow the trees in the ground say for two or three years. Then i could rotate the trees 180 degrees. Let them grow for another two or three years, then put them into training pots to work on refining the trees.

That's exactly how I grow on.

Al