bloom and fruit set
Hello! I am new to the forum (but have spent some time reading back) and I am hoping to get some advice on how to get fruit to set.
I have four trees. Two came from Four Winds Growers and are an Improved Meyer Lemon and a Eureka Lemon. They are currently 6-7 years old (I bought them as 2-3 year old plants in 2006). Two came from I know not where - they were a gift from my parents, and were bought at some local nursery or other here in Louisville KY. They are a Minneola Tangelo and a Washington Navel Orange. I got them in 2006 also and I have no idea how old they are. They each started out about 5 feet tall but seemed to be fairly recent grafts (maybe 2 or 3 years post-graft) despite the height.
All four live in containers and get full sun all day in the back yard during the summer, and come indoors for the winter to live next to a window and under grow lights. I keep them propped up on bricks, both outside during the summer, and indoors in the winter (the bricks are put into the drip pans so the plants don't stand in water).
The first year I had the plants, the tangelo produced 12 fruit, and the navel orange 2 fruit. The lemons were tiny so I pinched off their flowers, and furthermore the Meyer caught a bad case of foot rot and nearly died.
Since then, I have had great difficulty getting fruit to set and I'm hoping I can get some advice. Every fall when it starts to get cool the trees bloom like crazy, and then they do it again in the spring when I start the outdoor sun-hardening, but I'm lucky if I get 3 fruit to set on one tree, and I've never gotten more than 6 fruit in any given year off of the four trees combined.
Every other year I knock the oranges out of the pots, claw a bunch of soil off the root ball, trim the roots, and then repot them back into the same containers in a fresh soil mix (32-quart plastic pots). The lemons, which started out very small and have been growing rapidly, have gotten a pot upgrade every year until this year. They went from 8 inches to 10 inches to 12 inches, and then this year the Eureka went into a 21-quart. The Meyer lemon didn't get a pot upgrade because it was busy re-growing all the leaves I cut off it in November to get control of an Alternaria outbreak. It is doing great now! But it didn't need to be repotted because it didn't really grow this year. Next year it will get the 21-quart treatment.
In general, the trees grow quite well, and aside from the bad luck the Meyer keeps having, they are pretty healthy.
They just don't set fruit.
These last two years, the Eureka lemon has wanted to just explode with vegetative growth and it's hard to keep the size of it in check, so I'm wondering if I'm giving them too much nitrogen. My fertilization schedule is really not a schedule at all - I give the lemons, which are smaller, two tablespoons each of Citrus-tone and a little handful (maybe 2 tablespoons - it's not much but I don't measure it) of extra blood meal. The oranges, which are much bigger, get double that. This is about once a month but I don't keep a rigid schedule, and this year it's been less than that due to having to handle a scale issue.
Most years, whenever I think about it, I give them a liquid seaweed foliar spray + drench, but this year they haven't gotten that due to the scale thing. The scales are cleared up on three of the trees, so I'm going to start doing that again on the cured trees as soon as this brutal heat lets up.
I don't really grow the trees for the fruit. I really grow them just because I enjoy them, even when they bite me. But it was pretty discouraging to once again, this spring, see flowers break out everywhere on all four trees and get only 4 fruit total to set.
Any ideas would be appreciated!