Indoor lemon/lime - wilt leaves which yellow and drop

Question

After they had been outside throughout the summer, I brought my citruses inside. I've been having them for a couple of years and this is the first time I observe so much leaves being dropped. On the lime tree, they just go yellow and on the lemon tree, they wilt first and then drop. I also have kumquat tree which doesn't show any problems.

I don't believe that's because of too much watering since I've learned that lesson by loosing few trees, so I keep the soil on the dry side.

Indoor humidity has fallen to 50-60%. Could that be due to too dry air? Should misting help? Or it is a sign of nutrient or sun/light deficiency?

Any suggestion is more than welcome!

Lime

Lemon

Answer 1

I had a Clementine seedling for years that always dropped most of its leaves every time I brought it outdoors and then again every time I brought it indoors. It was light-related: the tree didn't like going from a mostly indirect-lighted location to a mostly sunny location and vice versa. I got rid of the problem by keeping the Clementine in a mostly shaded spot when it was outdoors. When it lost its leaves they always shrivelled on the twig before and dropping, which sounds like your lemon tree.

This site lists a number of reasons for citrus leaf drop - so many that "looking at it cross-eyed" should've been included in the list. The three major causes are changes to the light the plant receives, temperature changes, and humidity.

Answer 2

I think I've identified the problem. After most of the leaves had dropped off and the remainder wilted, I decided to repot the lemon plant. The longest roots were completely rotten and fell off. What has remained are shallow roots which still seem healthy.

I've replanted it into a new soil and water it just to keep the soil moist.

I guess, it was a combination of overwatering, dry surrounding air and colder pot temperature which drop overnight so the roots at the bottom rot.

What I'm not sure how to prevent this happening to other plants. If I don't water them, the shallow root will dry out and if I do water them, the bottom roots will rot :/

Answer 3

Perhaps better soil and better drainage is necessary to prevent root rot, I found that with citrus trees there really is a fine balance, if you're going to give them a lot of water you better make sure the light is bright and its super hot out so they can use that water right away, then let them do that for 2-3 days before checking on the soil to make sure that it's almost dried out before watering again.