Lavender frost damage on new plants!

michelle_hanna

Help! I just bought 12 lavender munstead plants a week ago. I’ve been keeping them outside but they haven’t been planted. I don’t have a greenhouse and didn’t want the inside temperatures to be too warm for them. I live in the US in zone 5. Last night the temperature dropped down to about 27 F or -3 C. It actually dropped about 2 degrees lower than I expected, and now they all have frost damage. :’(

A few of the plants have a good amount unaffected. Other plants are totally affected but there is still some green at the bottom. What can I do? I know they’re not dead and I can prune them, but EVERYTHING I read is about pruning of the whole winter damage in the spring, not about pruning frost damage on new plants. I’ve brought them all inside now and will continue to bring them inside at night when it drops below freezing until I can plant them after the last frost date. But when do I prune and how much? A lot of the damage seems to go straight to the wood, so I am confused. 

P.S. - I’m sorry that I’m an experienced American. I should have been born in Europe with Gardeners for parents who could have taught me more. But I love watching and learning from Gardener’s World from across the pond!

Fairygirl

Hi @michelle_hanna. I think I'd wait until the temps are more suitable for trimming those. The old stuff will help with protection for now.
There's some green stuff still there on that first one, so that's hopeful. If it becomes difficult to bring them inside at night, you can start leaving them outside with fleece or similar, for protection. Under a table or a seat, or against house walls etc will help too. A house wall especially, as it can just give an extra degree or two of warmth. 
The problem is that most plants are grown in quite protected conditions, so it can be a shock when faced with the real world. Once established, they'll withstand that temp, no problem. The fact that there are flowers on them shows they've been very cossetted. 

Not much consolation for you just now, but hopefully, they'll recover enough. 

JennyJ

I agree. Wait until the cold nights are over before you prune them. The damaged parts will give a bit of protection to the base of the plants.

Apparently they are hardy down to -15 (when they haven't been grown soft indoors) but that means they shouldn't die, not that there won't be any damage, so you might want to protect them in winter if the temperature gets into minus double figures. I think I would be inclined to leave the old flowers on over winter and prune in spring in your climate. The general advice here in the UK is to prune when the flowers have faded but we only have USDA zones 7 to 10.