perplexing indoor lemon tree problem

[troubled gardener]

I have a three year old meyer lemon three in a self watering container. I have had the tree for one year. The three is positioned at my south facing balcony window and because of the limited sunlight I also have a sunlamp shining on it for about eight hours a day. In December the tree produced two wonderfully ripe and tasty lemons.

Now on to the perplexing bit...

Since harvesting the two lemons back in December (2 months ago) my tree has been steadily losing leaves. The leaves appear to be normal when they drop without any discoloration. As of today the tree has only about 25% of its foliage left on the tree. But the tree also has two new lemon starts that seem to be doing fine (so far) as well as many new lemon blossoms just starting to emerge. So it looks like a leafless tree with lots of blossoms. I also noticed thorns on the tree (I thought meyer lemon trees did not have thorns) which I never noticed before.

Is my tree ill? Is the leave drop normal for this sort of tree? I really do not want my tree to die and any help anyone can offer would be tremendous.

[hendi_alex]

Sounds like too much water to me. At one time I had several potted lemon and lime trees. All developed thorns after two or three years.

[Kisal]

Do you provide your tree with sufficient humidity, either by misting is regularly, or else setting the container on a humidity tray? This is especially important during the winter months, because indoor heated air can be very dry.

It also might need some fertilizer. I understand there is a special fertilizer made for citrus trees, so you might want to try find that. I know they need to be fertilized in late winter, just as active growth period starts, as well as later in the year.

I have never had good luck with self-watering containers, for any type of plant. I much prefer standard containers, which provide good drainage and allow me to control the amount of water the plant actually receives.

Your "sun lamp" is a 'grow light', and not a heat-lamp type bulb, right?

[troubled gardener]

Yes the lamp is a grow lamp. I purchased it at a garden center.

I have been misting the leaves but not touching the soil as I have been relying on the self watering pot for that.

I have only tried fertilizing with a standard houseplant fertilizer since the garden center said that would be all I needed. That could be a the culprit but wouldn't the leaves show discoloration if it needed to be fertilized?

The reason I went with a self-watering pot was because I had such poor luck in the past with other indoor plants in regular containers. If I decide to repot it, is there a time of year that is recommended to be better than others? I hear that citrus trees hate to be moved.

[Kisal]

The fertilizer you choose should be high in nitrogen and acidic in nature. I think your plant may be responding to waterlogged soil, though. That's exactly the problem I always had with self-watering containers.

Have you checked for pests? I know scale insects are especially fond of citrus plants. Perhaps this Extension Service article about indoor citrus will have some information that will be useful to you.

https://www.colostate.edu/Dept/CoopExt/4dmg/Plants/citrus.htm

[troubled gardener]

Brainstorm...So if it is waterlogged and the self-watering pot is the culprit could I, rather than repotting the tree, just drill a hole through the bottom of the self-watering container to allow for extra drainage? Or do you suggest completely repotting?

[Kisal]

I think it might depend on the way the particular self-watering container you're using is constructed. How deep is the section that is filled with soil? Does it sufficient space for good development of your tree's roots? If not, then repotting entirely would probably be a better choice. If the soil area is plenty deep for the roots, then just drilling a lot of drainage holes might work okay. Again, it would depend on the actual design of the planter, I think.

The planters I had used wicks to transfer the water from the chamber up into the soil. If your container operates on that principle, I would be concerned that those wicks might start to work in reverse and suck moisture out of the soil. While you do want good overall drainage, you don't want dry areas to develop in the root ball. (I don't know that the wicks, if they're in there, would actually do any harm. It's just a thought that occurred to me.)

[thanrose]

The leaf loss is known as winter leaf drop. My citrus are in ground, so not a problem, but any citrus tree in a container will potentially have "winter leaf drop." It has to do with the temperature at the roots in the pot and the differential. I am not knowledgeable of how to handle this, just know that's what it's called.

Search online for winter leaf drop and you should find some answers.

[cynthia_h]

I've picked Meyer lemons and Eureka lemons in the Bay Area and in Florida. Every single lemon tree had thorns, so there's nothing wrong with your Meyer in that regard. Unfortunately....those thorns can be VERY long and very sturdy.

Cynthia H.
Sunset Zone 17, USDA Zone 9