Hi I have 2 bonsai that I have been successfully looking after. I have a Chinese Elm that was my first success. For the last 2 winters it hasn't lost all of its leaves and then the following season looks a little bare. It also has a moss or lichen problem maybe so I just wondered if someone can help me with this as I'm thinking it's sick.

I keep them outside, re-pot them occasionally with new soil etc and bring them in overnight if it looks like its going to go well below freezing.

Any help gratefully received! I live outside London UK.

The lichens grow in areas that have fairly good air quality (Low sulfur) and low air movement (High humidity).

nothing really to worry about, except that it block light to the branches which reduces backbudding. Also it may eventually block buds from opening.

With a soft toothbrush and some water you can easily remove them, especially after a day of two of rain.

ahh great thanks - I actually like to the look of it and moss etc - looks authentic / wild.

What about the tree not losing its leaves? it's like it only partially goes dormant - the leaves don't look dead - should I pull them all off and remove some of the lichens before spring?

It is a chinese elm. They are very slow dropping foliage. Semi-deciduous I would say. Don't worry about it.

Hi, ive just posted the same question about my Chinese elms, I should have looked a bit harder for an answer. I live just outside London as well and my 3 elms do not drip all their leaves, maybe our winters are not harsh enough.

Hi Rob - well I forgot to search first before posting so I'm guilty of that too. I wonder if it's better to pull the leaves off though, is the tree using energy keeping them going? Would this help regrowth the following spring??

Maybe I'll search for that unless someone comes along & answers it

Leaves are the source of energy for the plant (Think solar panels). SO do not remove them. The investments were making the leaves. Removing them weakens the tree.

`middle29 wrote:

Hi Rob - well I forgot to search first before posting so I'm guilty of that too. I wonder if it's better to pull the leaves off though, is the tree using energy keeping them going?

No. The tree uses energy to grow them, but they're not growing anymore. The leaves actually create energy from sunlight (though it won't be much at this moment). I just leave them on. The plant knows best when to drop 'm.

Also, the plant retrieves nutrients by breaking down the chlorophyll in their leaves. That's why they change color.

ahh ok thanks, good to know - I wasn't sure if they were still working that way midwinter. the leaves have become a bit larger over the last couple of years though which I'm not so keen on and i was just reading about defoliating in the summer to get smaller leaves - is that something I should be cautious of? Can I attempt that as a beginner? Or should I just prune the larger ones in summer?

Thanks for your help, also its reinvigorating my interest in my bonsai

Once your elm starts pushing buds you can remove the old leaves. Then watch the new growth. You should notice that the first two, three leaves are significantly smaller than the rest. So trimming back to those after say 5-10cm of new groth has formed, will get you smaller leaves.

I think however that your whole tree could probably do with a cleanout. When is the last time you did a full cleanout, wiring etc on this tree?