Herbs outside in the frost

jamesbenstead6 · March 2022

I've got a glut of seeds that have germinated in my probegator that now need potting up. Problem is my Poly tunnel is bursting at the seems. I've got some herbs in pots that I could put outside but there is cold weather forecast this week. Will a frost hurt mint, parsley, chives, thyme, sage, fennel, tarragon. The poly tunnel is unheated at the momment.

Dovefromabove · March 2022

French tarragon is tender so don’t risk that.

As for the rest, how well developed are they? Whereabouts are you, and have they been hardened off at all?

Ordinarily they’d be ok, but if they’ve been under cover and we’ve had this warm spell their new growth might be a bit lush and tender.

Could you put them out during the day and cover them or pop them back inside at night?

Fairygirl · March 2022

I wouldn't be worried about mint or chives, unless they're tiny seedlings or similar.
They're quite hard to kill. Thyme is hardy too, unless it's tiny and immature. Sage is iffy here anyway, so your location is a factor.
I don't grow the others, apart from ornamental fennel, which is also fine if mature enough. I've had some sitting outside since last year, and they're recently planted. They've coped perfectly well with our recent frosts, but the edible one might be different.
Wet cold is generally far worse for many plants than a bit of frost, but the size is a major factor too. As @Dovefromabove says, some of those aren't hardy plants, so you'd need to harden off gradually according to the size and maturity of them.

jamesbenstead6 · March 2022

Thanks for the tips. They are all last years cutting taken last spring/summer. They have been in an unheated poly tunnel all winter but obviously the past couple of weeks the daytime temps have been 30C in there. I'm in the South East Hitchin, so fairly mild. Unfortunately once I pot the seedlings up I'll have no room even on the floor and under the benches will be full. I can leave then out during the day and cover them with a plastic clotch to provide a similar environment to the poly tunnel night.

Dovefromabove · March 2022

jamesbenstead6 said:

... I can leave then out during the day and cover them with a plastic clotch to provide a similar environment to the poly tunnel night.

Sounds a good solution ... they should be fine ... even better if you can do that in a sheltered spot near the house where the frost is less likely to penetrate.

Give my regards to Hitchin ... the town of my birth (for various obscure reasons) ... I didn't live there (lived near Woburn Abbey) and have never re-visited that I can remember, but as you can imagine, I feel a tenuous link ...

Fairygirl · March 2022

I agree, that should be ok. The biggest problem is the fluctuation in temps - especially in a polytunnel, but a bit of gradual hardening off should be fine.

Herbs outside in the frost

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