Jack,
Why do you think keeping your chestnuts in 3 gallon root trappers was too much? Couldn't you have transplanted them to 5 gallons?
I've tried a number of methods, but the one I like best is this: For the chestnuts I grow from seed where I'm trying to maximize growth, I start in RM Express Tray 18s for 12-16 weeks under lights in the winter. I then transplant them to 1 gal RB2 containers when I take them outside in the spring. In late spring I transplant them to 3 gal RB2 containers and keep them 1 growing season until fall and then plant them. Details with pics are in this thread:
http://www.habitat-talk.com/index.p...th-rootmakers-transfered-from-old-forum.5556/ I typically don't keep them for a second growing season. I use a tractor auger when planting them. I'm planting them in heavy clay. The difference in water infiltration between the promix I use in the containers and the heavy clay is problematic. I've developed a technique for planting from rootbuilder II containers in heavy clay that works well. It depends on the auger diameter being very close (slightly larger) than the container. I don't have an auger bit for my tractor the right size for containers larger than 3 gal. The technique also depends on hole depth and I'm not sure my tractor could handle a larger bit at the depths I need.
The AU Buck trees were a special case. I bought them as nut grafted trees from the Wildlife Group. My plan was to transplant them from the 5" roottrapper bags to the 3 gal Rootbuilder II containers when I received them in November, keep them for one growing season, and plant them in the fall. I got a surprise when they produced a few nuts that first summer on my deck. I decided to wait for the nuts to mature and collect them for planting before planting the trees. By the time the nuts fell, it was in the middle of my hunting season I just did not get a chance to plant them. I considered planting them this spring, but again they produced nuts. I could have transplanted them to larger containers, but planting would be more problematic. I also thought that transplanting them to larger containers may cause them to put more energy into vegetative growth and less into nut production. I decided to sacrifice potential growth to ensure the nuts matured. Last year I only got a couple nuts that matured. Most aborted. This year only one aborted and the rest matured.
I've had a few conversations with Dr. Whitcomb. My understanding is that for optimal root development you want to follow the 4" rule. When a root gets pruned most of the root branching occurs within 4" of that prune. So, if you start with large containers, you get less root branching. However, once the roots fill the container, it becomes hard to top-water, and growth slows because of the root ball limitation. This can force a tree from the normal vegetative growth stage it would otherwise be in if young into a fruiting stage. I found this out working with Jujube trees after discussing the fact that parent trees in the field were not producing fruit but trees I started from root cuttings were fruiting on my deck in their first growing season with a professor that specializes in Jujube. He suggested that when I planted them in the field, they would likely stop producing fruit and revert to vegetative growth for a few years.
The reason I believe I kept AU Buck chestnuts in 3 gal RB2 containers too long is that they grew well last season and growth this season was minimal.
Thanks,
Jack