No
A colander would would keep roots shorter, and help roots to be more branched. Better ramified. BUT, a tree in a colander will need more frequent watering than a tree in a pot or in the ground. It will also grow a little slower because the roots are being ''air pruned''. This is a technique for pines, especially shohin pines. It is really not necessary for pines, just one option for pines. It is usually a bad choice for deciduous trees.
If you bury a colander in the ground, you have essentially a ''ground growing'' situation because all the roots can escape the colander. There is no benefit from a colander buried in the ground, if anything you will have trouble digging it up. You will have all the flaws of ground growing.
Sorry , not sure why you feel it works that way. That has not been my experience. Some of the roots escape, the rest are kept in a more compact form which allows the tree to be transferred and repotted with ease. It is important to sever the escaping roots from time to time to prevent the same issues as ground growing as alluded to above. They are very easy to dig up if done at least annually. The real problem is Andersen flats placed on the ground for several years or even a regular bonsai pot that is allowed to stay on the ground for several years with a healthy juniper extending downwards. But then that is a case of neglecting the situation, is it not. never felt Bonsai was a plant and forget hobby.
The use of the colandar allows me some of the benefits of ground growing such as the even temperature and stable ground conditions, also it is good to rotate the trees when the roots are severed for even development and it is good to work the roots more frequently than normal extended ground growing.
I use them for pines only in the early stages , first three years and do not use them with most deciduous past the second year. Temporary containers for specific purposes. Examples below. Pines year two and three. Maples year one and two. Seedlings/ cuttings through winter in greenhouse.
Years ago i tried them on the bench and found them to be unstable and dried out to fast, so i switched to setting them in the ground. If using on the bench for air pruning then i would reccomend larger sizes with stable flat bases.
Would not reccomend for cypress or cedar as they like moister conditions than pines and colandars dry out quicker and require more frequent watering.
PS: my comments are based on repeated use for specific purposes over many years. Perhaps they are only useful if one adapts to their strengths and avoids their weaknesses. Certainly the climate and care routines make a difference.
