Ive got an orange,grape vine,grapfruit and lemon tree,all good size.Im in CA,what and how much should I feed them with right now.I have a dog that can get to them so nothing he will eat I guess.
Use fertilizer spikes around the base of the tree or pound a metal pipe in the ground a couple of feet from the base of the tree, fill with slow release fertilizer and then fill the pipe with water every couple of days. remember, this will feed the tree for 6 months to a year. Also, the dog will not be able to get to it.
I have a lemon tree and when I change the water in any of my tanks I siphon the water with a hose long enough right to the base of the tree. I have to brace the branches of the tree every year since there are so many lemons on it or otherwise the branch might brake of from the trunk because of the weight.
My tank drains to my Orange trees and they produce some very great tasting Oranges. I've sold a few sometime ago to help fund my fish addiction. I bagged up half a dozen and had my kids sell them off freeway off ramps.