I planted three semi-dwarf cherry trees here in the Seattle/Tacoma part of Washington state about two years ago, two are Rainier cherry trees, one is a three in one cherry tree to act as a pollinator. They're all about 10'-12' tall. The first summer I got excellent fruit production from all three trees but this summer I got hardly any fruit from any of them although I did get a little bit from each tree.

The trees are kept nicely watered (but not overwatered) with a soaker hose. The trees look incredibly healthy, very thick amounts of nice green leaves. In the spring we've spread compost around the trees.

Any idea what may be going on? We haven't fertilized them and I'm wondering if that's the problem. If fertilizer is recommended any suggestion of type/brand and what time(s) of year to fertilize?

I'm totally new to cherry trees and am in need of help. Thanks in advance!