WE have lemon, satsuma, grapefruit, orange and lime. What the county agent told us for our yard is 1 lb of 13-13-13 for every year the tree is old. We kinda go by how big the circle of the drip line is. We have found a great way to fertilize is to punch a hole at the drip line with a recking bar. wallow out a hole and poor in 1 lb of fertilizer that happens to be a red solo cup full. if the tree is small we punch 2 holes oposite each other. If its large it gets as many as 10 holes around its drip line a couple paces apart. We will be doing this next week or later, Febuary is the recomended month for fertilizing and pruning. As mentioned Lsuagg is a great sorse. Dan Gill has a link to his site and he is louisiana's garden guru.
When we get around to doing this I'll post a few pics and the link. Our beloved lemon monster lost all its leaves and seems to be headed for the grove. It's 12 years old and we get 10 to 16 gallons from it every year so it will be greatly missed. One satsuma died so we are starting another now 2 years old we been covering it every freeze but it dont look good either. We love playing in our yard but I gotta warn ya it aint all goy ya loose things and in a WAY THAT MAKES THE FRUITS OF YOUR EFFORT ALL THE MORE REWARDING. Here is a video we made of harvesting olur beloved lemon monster, I sure hope it pulls through, but if not we will start over and look forwards to doing it again.