Most of us are going to have that urge to begin fertilizing when we see our trees begin to grow. But take a moment to consider: A developed tree has a totally different fertilizing program than a very young, undeveloped tree. That older, ramified tree might be fertilized first in May; the undeveloped tree might be fertilized as soon as its buds begin to swell. Which might be now!
And one more quick tip. For those of you who like growing maples and other deciduous trees that might develop a marvelous fused nebari, when that tree is young, fertilize right next to the trunk of the tree. Fine fusable roots will grow right under your fertilizer cakes, the kind that develop into the solid nebari pancakes that we see on really old bonsai and trees in the wild. If we fertilize only at the outside of the root system, the roots will simply try to run to the pot wall… We want them to stay closer to home in the early years.