AusBonsai

Hi,
A question that I can't seem to find the answer for so any help would be great. Some of my zelkova have not dropped there leaves and with the coldest part of winter behind us I don't think they will now. Do I defoliate them before I root prune? I have read anytimes that u shouldn't repot when the still are in leave and last year I lost a couple because of this (pretty sure that's why they died anyway)? What's everyone's thoughts on this? The trees are mostly one year old seedlings and a couple of two year olds??

This time of year it makes no difference at all.

I am no expert but just a bit of care here. If you root prune and re-pot, fine. But defoliating it can be done in spring, I would let it settle first before I took all its leaves off. I know bonsai sometimes do not shed leaves but the point of defoliating is to make the leaves smaller.
They shouldn't like it trying to settle and throwing out new roots, and then having their leaves taken away at the same time so they can't photosynthesise Might stress them too much.

If you are planning a radical root prune, I'd remove some old leaves. I'd think you should be fine if you remove them all as well, particularly if you do it just before bud swell. The other option is to prevent transpiration by spraying them with a wax product or after repotting to place them in a high humidity environment for a for weeks.

Don't bother defoliating. Do the root prune and then the new buds as they expand will force the old ones off or they will fall soon after of their own volition anyhow.

Grant

I agree with Grant and Treeman. If your zelkovas died last year is was NOT from having leaves when you repotted. I have occasionally had them fail to bud in spring but not from repotting - I suspect fungal problem.
Other semideciduous trees can be repotted with leaves still on - Chinese elms, Chinese quince and of course all the evergreens can be repotted with leaves still active.

Fantastic help! Thank you all, the roots are coming off tomorrow .

Best of good luck. Let's know how you got on, for our own info. I'm studying Hort IV at TAFE, I was given credit for other Hort Certs and Diploma in organic agricultural production, so chose bonsai. It's a very toiling exercise. As it is on line, I have to go through all the exercises myself, like re-potting, air layering, seeds, and pruning, soils etc, etc. So I am learning myself but one thing I know, is defoliating at the wrong time of year can be stressful. One of my trident maples, lost its leaves, from lack of water. It had rained but these pots didn't receive them and we had a really hot days. But 'she' sprouted new leaves almost within weeks, but much smaller. She was then re-potted, and is going OK. There's no reason why you can't snip off some of the older leaves, leaving the stalks on the tree. But I would withhold total defoliation until it is settled in its new pot.