I was given a Chinese elm bonsai as a gift in October. I've grown very fond of it. I have it sat inside a foot or so from a huge south-east-facing bay window where it gets lots of light - I'm in a flat so my options for putting it outside are limited.

Not long after it arrived it gradually lost its leaves (I figured this was natural for that time of year), but they were quickly replaced by a new batch and it looked very healthy again. I tried to keep it shaped but gave it some space to grow.

In February/March time it began to lose all its leaves again, and they were again fully replaced by May and it again looked really healthy and bushy. It's now beginning to lose its leaves again - I'm sure this cannot be a healthy or natural cycle.

I keep it well watered, feed it occasionally, and spray the leaves too. I don't think I over-water it... but then I'm really not sure! I wait until the soil is just slightly damp a centimetre or so under the surface rather than watering it on a fixed schedule. I don;t let it dry out entirely. I haven't trimmed it in a month or so, it's looking a tad wild.

As you can see from the picture the leaf loss is patchy and uneven at first - mostly in the lower branches, but then the problem spreads. They go dry and crispy before falling off - rarely fully yellow. It start growing new buds before all the old leaves fall.

I do have a tiny balcony that it could be moved to, but it;s a very exposed and windy location and there's no obvious place to put it other than the floor or a set of shelves that wouldn't give it enough vertical space.

Any tips would be really welcome.

Myring wrote: I have it sat inside a foot or so from a huge south-east-facing bay window where it gets lots of light - I'm in a flat so my options for putting it outside are limited.

Welcome, Myring.
This looks like they are drying up, fast. It's not normal for an Elm to lose all foliage every two or three months.
But, as I can see from your pictures, it is sitting VERY NEAR an air conditioning system, right?
That can be one of the reasons the leaves are dry; the air around it is... Way too dry.
I would boldly face the elements (including wind) with an Elm rather than keeping it indoors.

Thanks Clicio. It's near a radiator rather than an air conditioning system. The radiator is only on for a few hours in the evening and morning, on cold days. Is that likely to be the problem? The cycle of leaf falling and regrowth hasn't been connected to periods of regular use of the radiator as far as I can recall.

Myring wrote: The radiator is only on for a few hours in the evening and morning, on cold days. Is that likely to be the problem?

Yes, it could well be.
Radiators are known for killing plants as they create a very dry microclimate around them.
Why don't you try to move the plant away from the radiator, as far as possible? And then monitor the progress?