I have two plum trees next to each other, both self fertilizing, in past years i have fed them with all sorts,

but neither of the tree's cropped very well, why is this ?, This year i didn't feed them anything, but both tree's have croped very heavy, why is this ?, and should i feed them now, the fruit is the size of small grapes %26amp; growing.

I have two plum trees next to each other, both self fertilizing, in past years i have fed them with all sorts,
I have fruit trees as well and some years I get very heavy crops and some years nearly nothing. I believe it depends on the weather and when the bees are pollinating. Some years the trees are ready to be pollinated but the bees aren't around yet so they miss pollination. I never use fertilizers on my fruit trees so I don't think it has anything to do with it. If you want bigger fruit you should thin the fruit out when you have a heavy crop otherwise the fruit will be small. Hope this helps.
Reply:You should fertilize them in the fall.