Before that magical bonsai tree of yours reaches the refinement stage, focus should be on growth and development. A shallow ceramic pot looks great, but may not be ideal for optimum growth. Wooden training boxes allow for bespoke dimensions to accommodate any size of tree. By allowing your tree to build up it’s resources and develop a strong(compact) root system, you propel it’s rate of growth, moving the tree ahead. There is good reason why bonsai professionals use boxes. Here are some benefits of using training crates.
1. Build to size, any size. Finding the perfect dimensions in a training pot for your tree can be challenging. Make your box to any specs.
2. Inexpensive. Buy affordable planks of wood. Use wood you find or already have.
3. Easy to customize. Attach handles for large heavy trees. Fasten screws in the wood for guide-wire mounting points or tie-down wires to secure on the bench or railing.
4. Dependability. As long as you’ve made the box well enough, it should hold strongly for years. No worries about damage, chips and cracks. It won’t split or fall apart after a long frosty winter. A wood box can take quite a beating and still remain functional.
5. Insulation and protection for the root system. The wooden box maintains a fairly steady temperature compared to ceramic pots or plastic pond baskets. This offers insulation for the roots. It can have as few or as many drainage and wire-tie holes as you wish. Plastic training pots and pond baskets can be drilled too. Pond baskets however, leave the root system somewhat exposed to frost.
Get that tree-in-training out of that plastic nursery pot and into a handy wooden box. Make it shallow, but wider than the old pot to allow for root growth and nebari development. Space out the bottom of the box and cover with screen for drainage or you can drill holes once it’s assembled. The method I like involves a flush bottom with feet attached afterwords. I then drill drainage holes where needed. You can make it as simple as you like. See the photos for an example. With wood screws, nails/staples, and the wood, the average cost per box is $5-$10. That’s pretty cheap housing for any tree in training. If you have the materials around already, well it couldn’t be any cheaper.
Maybe your tree is ready for a bonsai pot. Here’s an older article to read on pots(click).