Fruit trees generally don't need a lot of fertilizer. But if they do, late spring and early fall are usually the best times to fertilize. The tree must have leaves on or it won't take up any nutrients. This is because the nutrients are taken up in the water that is transpired thru leaves.

The other suggestion I'd have is that your trees usually only need fertilizer if they lack sufficent vigor. There can be cases of micronutrient deficiency with good vigor or other special situations like very sandy or infertile soil. But if your trees have good vigor, healthy looking leaves, and bear regularly, then they probably don't need any fertilizer.

A moderate amount of balanced fertilizer in fall or spring probably won't hurt anything.

The Fruitnut

They seem to look pretty good, they just seem not to grow much.
I have a braestar apple that I planted last year
and it started getting leaves on one side of tree and then
it quit growing. We have had a couple good frost the last
few nights.

If your trees aren't growing enough, they may need some nitrogen. But it could also be a problem with too much competition with weeds or nearby large trees. Applying a good mulch for several feet around the tree can help supply nutrients, conserve water, and control weeds.

The Fruitnut

Thanks,
I will try some nitrogen, I do have them mulched.