Roughly how much fertilizer to give a 15-plus year old lemon tree?
Fertilizer for Lemon Tree
Certified GKH Gardening Expert
Basically the amount of fertilizer used really depends on how tall your lemon tree is. If your lemon tree is 20 feet tall, for example, you would apply fertilizer in a 20-foot circle around the tree to ensure that you reach the entire root system.
This article will provide more information on fertilizing lemon trees: