How far do the roots grow from the rootstock after citrus trees planted in the ground mature ? I want to fertilize a meyer lemon tree planted in the ground. Should I apply the fertilizer starting just past the drip line to 25 feet.

Generally, the recommendation is to fertilize the area from about a ft from the trunk to a couple ft beyond the drip line-- 25 ft would be a little far from most trees--unless it is really big.

Not contrary to the above advice, my large and old eureka lemon is quite vigorous and we've pulled roots extending over 30 ft from the drip line. How big is yours? Depending on surrounding environment it's not *usually* hard to check if you're willing to dig a few small holes around the perimeter.

There was some work done back in the late 60s or early 70s, with mature groves of oranges on rough lemon roots in central Florida. Groves planted on opposite sides of US highway 27, in Polk County -- a 4-lane US highway, with a wide median, and wide area off to each side. Light, well-drained sandy soils. So the groves were likely at least 200 feet apart (I'm sorry I don't have the written reference to this -- I'm remembering it from my intro to citrus class that I took at UF). There was evidence of roots intermingling out in the middle of the median, allowing transfer of nematodes. So at least in that case -- mature, rough-lemon-rooted trees, a radius of over 100 feet was possible. That doesn't mean the bulk of the roots were out there, and we still recommend irrigation and fertilizer under the canopy drip line; but at least some roots can go very much farther.

wow i never would have thought over 100 feet was possible.

I was outside measuring yesterday and there were absolutely lemon roots 49 feet away from the drip line, though only 12 inches below the soil. The area it was in was very poor quality soil, heavy clay, with nothing growing and never watered -- but it had a fairly shallow water table due to hard pan. The neighbor is notorious for over-watering leaving 2 inches of standing water in her backyard -- I'm guessing the water source for the tree since I would *never* water it, until two years ago when I made landscape changes.

The tree is just under 20yrs old. I don't know the rootstock, but I assume its on lemon. With this mature tree I can no longer discern (if there ever was) a graft point.