I purchased 8 dwarf maples from a nursery in northern California. They are 1-gallon size. The nursery grew them in a mix that included lots of shredded redwood and they arrived with the root ball (sans pot) wrapped in plastic.
I would like to grow them on to sell at a future club show, but I’m not sure what type of pot and medium to use. If they were for myself, I would put them in a large Anderson flat, potted in a mixture of bark, lava, garden soil and some bonsai mix, so that the trunks could enlarge. I don’t have enough flats to do this, though. I think it is too soon to put them in a bonsai pot with akadama. Should I find large shallow pots, put them in growing boxes, or something else?
The grower recommends planting them in a bark heavy growing medium, but I’m not sure this is the best strategy.
I grow similar sized maples for further development in about 8" (20 cm) diameter plastic bulb pans using a mix of sieved bark and pumice with some added manure mix. The bulb pans are a bit larger volume than the 1 gallon pots, but about 1/2 the depth.
For growing out maples I have been using coarse perlite and a good potting soil like Fox Farms and use these plastic pots similar to bulb pots which range from 8” to 14” with a height of 3-5”. They come in a ten pack
Both the bowls and the saucers look good. I use a series saucers like these to grow some of my maples once I have started to develop the spreading root system needed for a good nebari. The biggest issue is that you have to add drainage holes. I like to melt 1" (2.5 cm) diameter holes in the plastic saucers. You can drill them, but they tend to be a bit brittle and can form cracks starting at the hole.