What kinds of trees and what kinds of shrubs? Most trees live well without fertilizer. Is this a flowering or fruiting tree? If your shrubs are evergreen, do you need to fertilize them? If they are flowering, fertilize after they have finished flowering, and not after Labor Day.

The trees are some kind of Maple that were planted Nov. 2004. The shrubs are a mix of hollies and indian hawthorn. We live in a new house and all the landscaping was planted in Sept 2004. The shrubs are very small and I want to encourage their growth as much as possible.

Well, if it is a Japanese Maple, all I can tell you is, don't expect alot....these are notoriously VERY slow growers. Indian hawthorns are blooming now, so I would wait to fertilize them. I'm not sure about the hollies.
I can't remember. But it would probably bee alright to fertilize them now. There is a fertilizer called 'Hollytone' that is good for your hollies. It is also good for other shrubs as well. I know Home Depot has it.

Fertilizing to push growth is counter productive to plants. If we allow them to grow at a normal rate for their species, they will also develop strong, far-reaching roots at the same time. Excess fertilization forces top growth at the expense of root growth.

Keep your plants well mulched, and offer very conservative applications of any all purpose fertilizer. I do like Holly-tone, as it has a low percentage of Nitrogen. Use less than the directions call for. I can't suggest how many times a year without knowing more about the type of soil you have.

I have brand new landscaping, too. I'll be fertilizing little if any this year. Subsequent applications will depend upon the plant's appearance.

In your location, never fertilize any woody plant from fall through early spring.

same as above.
mulching in spring and fall with a compost/manure mix has always worked for me. mulching also keeps weeds down that would be competing with your plants for nutrients. also, its cheap and easy!

Fertilizing landscape trees does not result in increased growth. There are adequate nutrients in the soil. The limiting factor for most trees is water. Source: Journal of Arboriculture and Journal of Environmental Horticulture.

Use this time to take some soil samples to send off for testing via your local extension office. Non-native soils or soils that have been put through the construction process may very well need to be fertilized at some time, but you really shouldn't do so without knowing that for certain.

Be sure that your trees and planting beds are properly mulched, as well. Truthfully, one of the single most important (beneficial) things you can do for your plants is to maintain a 2 to 3 inch layer of organic mulch over as much of an expansive root system as you can, but never right up to the trunk.