I use Grow 7-9-5 on almost all my containerized plants (except plumeria, which get the Bloom) and have good luck with it in my conditions. A lot is going to depend on the environmental conditions, frequency, strength, etc...
That being said, the maples probably aren't going to need a lot of phosphorus unless your soil is lacking in it. My local soil contains plenty of phosphorus so we really only need to add nitrogen and a little potassium for in-ground things here. But that's in Colorado.
If you want to know for sure what fertilizer you need to use, soil tests are usually available from your county / state / state university for about $20-$30, and will generally come with a recommendation for exactly what nutrients you need to add for optimal plant growth. Anything other than a soil test will just be rampant speculation about what fertilizer in-ground things need, and even reports of success from others is only applicable to their particular soil situation.
Kevin