Hey everyone,
So in regard to thickening a trunk, I’ve seen that it is a great idea to grow a tree in a colander. When doing this, do we need to plant the colander in the ground or no, and is there a difference between planting the colander in the ground vs not doing so?
Thank you.
The colanders are normally kept above ground. It uses the “air pruning” of roots theory.
I am sort of experimenting on the same thought process. I’m using fabric pots and burying it halfway. The substrate in the fabric pot is akadama, pumice and crushed gravel ( for maples) or lava rock ( for conifers). I started this year. My 2 maples, lodgepole and JBP are loving it.
I have 1 white pine in a colander above ground. 1 juniper in a pond basket above ground and 1 in a fabric pot above ground. All of them are growing well. We’ll have to wait for the roots and trunk girth.
1 had 2 maples planted in the ground on tiles and thickened up fast. Lost 1 to verticulum wilt 
I would think that if you plan on putting the colander in the ground, you may just want to fully plant the tree without it. When you pull a colander combo out of the ground, it would probably need the same after care as a field grown extract (due to root reduction) but the colander might have disintegrated to the point where it’s just a mess in the root ball.
But YMMV. It might be a handy way to let the roots grow wild, while also keeping some nice and tight and with a pre-defined radius to trim back to. I think the sack and tile methods are a bit more popular for controlling growth of material planted into the ground for development.
Yes. That’s why I’m trying the fabric pots, big enough to accommodate 2 years worth of growth. I want to separate the bonsai soil from the garden soil, and digging would seem easier.
I forgot to mention that there are “tiles” underneath (saucers, or gallon covers with drainage holes, or those orange discs used on pots to encourage food airflow underneath, and the likes).
Awesome, thank you guys so much for your help! I’m sure I’ll have many more questions to come lol 
No problem. I’m a beginner myself, but there are tons of great people here on the forum that can help us all grow.
There is a book produced by Bonsai Today - Masters’ Series PINES. In the book you will find an excellent article about using colanders and growing pines from seed by Kusida Matsuo. One of the issues you should be aware of when using colanders is that the same aeration that accelerates growth also dries out the container more quickly. In hot weather be prepared to water several times during the day. Does your work schedule allow for that? Additionally, the article is a go to manual for growing pines seedlings. Do it. In bonsai, ten years is a drop in the bucket.
Awesome David, thank you! I’ve actually got some pine seeds growing right now so that would be a tremendous resource. The caution about the colander is extremely helpful; I would never have thought of that.
I live in the sub tropics in Australia, and have found that the fastest way to get growth here is to put the plants into colanders, and sit them on the soil, and then surround the pots with hay. The other option is a hay bale style garden, where the bales are prepared by watering and fertilising for two weeks beforehand, then push the colanders into the top of the bale. The bales break down over around 6 months here, YMMV, and at the end of six months you just pull the plant out (still in pot or colander,) root prune the excess, and then put it back for another few months…or until it’s time to repot. My timing is this…start the bales in early Autumn, and by late Winter you’re good to go with root pruning and repotting…