Hi,
I have had a lemon bonsai for about 18 months now and it has been sick for some time. The tips of new leaves tend to go brown after they reach full size and the leaf later drops off. I lose maybe one leaf every three months.

I water it so the soil is always damp to the touch and fertilize it once a week. I do this for my other two bonsai, a ficus benjamina and a Fukien Tea, and they are both fine.

It is in a well lighted kitchen not far from a large window.

I'm fairly certain this must be a watering/fertilizing issue as none of my trees have any pests I can see.

I am tempted to read forums on care for normal fruit trees but I think watering for full size trees is different so am reluctant to follow advice I find there.

I would be grateful for any help,

Bungee.

Hello,
The lemon bonsai tree is one of the most popular choices available because it grows fast, has extremely beautiful flowers, and gets full of fruit right from the completion of its first year itself.

Tips for growing your indoor lemon tree : -
WHAT TO LOOK FOR
SOIL
TEMPERATURE
LIGHT
MOISTURE
POLLINATION



Thanks.

Being a citrus tree, you need a soil mixture that is slightly acidic, you can acheive this by adding peat moss or pine bark to the mixture.

In springtime use high potassium fertilizer to add root grown and fortify the tree's wood.
During the spring and summer months, use only slow release organic fertilizer, otherwise roots can be damaged. To Promote large blooms and fruits, use an organic 4-13-1.

Generally, wait fruits drop before doing any fertilization.

...I lose maybe one leaf every three months.

I water it so the soil is always damp to the touch and fertilize it once a week....

If your citrus has any size to it, one leaf every three months sounds normal to me. My lemon drops most of last year's leaves before the new growth appears in late winter. You might let it go just a few days longer between waterings if it stays cool in the winter, but it sounds like you're doing OK to me, especially if it makes fruit every year. Make sure you don't have any scale bugs and scrape them off if you find any.

Do you take yours outside for the warm, summer months? I do. Rainwater helps wash accumulated fertilizer salts out of the potting mix. Good luck.

I don't know where you are, but if you are in a frost bfree place then it really would be better outside in the sun. You could be overfeeding if it noy doing so well, also could be a mineral deficiency,
Geoff.