The last couple of years, I have dumped all my mini roses from the garden and containers into a big hole and have covered them up with peat moss as well as an upside down planter. Mini roses are not hardy here (zone 3) and I lose fewer roses this way. We have chinooks throughout the winter which are quite warm. Dessication kills a lot of plants here. So during the last chinook, I dug up all of my mini roses, potted them up, and put them under lights for 16 hours a day. I plan to start hardening them off as soon as it is warm enough, even if it is only a couple of hours every day. So these roses will be fully leafed out and probably blooming by May, when I transplant them into outdoor containers. As it is, several of them are starting to bud.
Last year, I lost only one plant, and I have one plant which seems to be following the same path - the leaves start off a nice green, but quickly shrivel into a light brown crumble. I thought the plant last year might have dried out but that isn't the problem with this one. I've seen similar damage on leaves if I rushed hardening off, and so it might be light damage, but that doesn't really make sense to me because it's probably the lowest plant under the lights. There's a good 6 inches or so to the light.
Any ideas what might be the cause?
