Watering a potted Meyer Lemon tree with a tight root-bound root ball
The situation: We've had a potted Meyer Lemon tree that was in a small pot for years and it got seriously root bound. I re-potted it in a much larger pot a few months ago. I’ve been watering it every 6-7 days (after probing the root ball with a moisture meter daily and it finally reading "dry,"). I've also fertilized twice with a 10-20-10 citrus water-soluble fertilizer at a 10-12 day interval. Except for the tight root ball, the drainage is great. The tree looks pretty good and has about 8-10 small healthy green lemons growing. So that’s good. But it also is sprouting more new blossoms and many of the small fruit that have been growing are now quickly turning yellow and dying. (See photos) I think what's happening (I could certainly be wrong!) is the root ball is holding the water for a long time, perhaps too long. The new potting soil around the ball is, of course, dry as a bone by the time I re-water. (With a tight root ball it's really hard to know when to water this thing!) I don’t know if this is typical and just the way a healthy potted Meyer Lemon tree grows or if it’s a problem because of my watering or fertilizing. In the photos you can see both the healthy fruit and some of the yellowing smaller fruit. I would appreciate any thoughts you might have. Many thanks. Bill
That's a small pot for a Meyer lemon. And being a clay pot it breathes/transpires and will dry out rather rapidly. I think water management should be your main issue.
It's possible that the root binding in the previous pot has created circling/girdling roots that are constricting the main stem and compromising uptake of water and nutrients. The only way to assess this issue is to carefully dig around the base and try to determine if there are girdling roots. If that is the case, you may or may not be able to do anything about it. Except to consider starting over with a plant with a better root system and less compromise to complicate the growing conditions.
The water issue may be the reason for the leaf discoloration and apparent nutrient deficiency, and also the suppressed fruit development. But to cover the bases I recommend that you switch to this fertilizer because its much more complete with mineral and biological slow release components: