After doing some research, I think I decided on a 3:1:1 mix of the following for my potted maples- Composted Bark Perlite Loam Does that sound resonable? From my understanding, this mixture should allow enough air into the rootzone, drain properly, and still provide enough moister. The climate here gets maybe a couple weeks of temperatures 100F + in the summer and a couple weeks below freezing in the winter. The trees are about 2 and 3 feet right now. Do I fertilize at all? In the spring when I repot? If so, how do I fertilize them? Thanks
Try to find out what a successful producer in your area is doing and ape that. For one thing, mineral content of irrigation water affects fertilizers. If somebody nearby, that has similar water to yours has hit on a winning combination, that's what you want to do also.
You can fertilize lightly with an immediate release grannular in the spring but go light. As Ron points out some water sources, especially those high in chlorine, can casue or worsen salt build up in potted plants that can damage roots. This can be exacerbated by the use of extended release products when maples are not grown in cotrolled environments like under shade cloth or poly-covered hoop houses. It is best to rely on your soil mix to provide nutrients up to around 5 gallon size but if the plants you have are used to fertilizer due to how they were grown before they came to you it may be necessary to supplement some to keep them from stagnating. You might use something as light as kelp extract up to something like an azelea or rhody fertilizer. Even many vegetable fertilizers are good and contain extra calcium which we like for our plants. I would think you would want to be in the N3-6/P4-8/K3-6 range with your ferts. Another option is to just use a little fish emulsion in spring or a 1/4 strength miracid. When you are up to the 5-10gal. size maples you will want to use the grannular followed by a dilute mixture of a liquid a few weeks before the hotter weather. I would say that means the grannular in April some time and the liquid in early to mid june. It is always easier to start with less than more as a damaged plant is much worse than an underfertilized one. Keep in mind that all ferts should be applied to a moist soil and then watered in well over the course of a few waterings. If you do fertilize regularly and have a relatively pure or low mineral water you will want to flush the soil a few times each growing season so that 2-5 times the water-holding capacity of the pot runs through to flush out or dissolve salts in the soil. Hope that helps and if you can find someone local to help you that would be great. Keep in mind again that if you grow your maples in a more exposed situation you will not and should not fertilize to the degree a grower would in more climate controlled situations. Additionally, over time, you want to reduce the dependency your plant might have had on fertilizers in the hands of a grower without allowing it to stagnate on you. Cheers!
