Is it too early to plant out California poppies?

I’ve been overwintering California poppies in a cold frame and they are now hardened off. They are well grown and outgrowing their pots. I’m not sure how hardy they are and a little worried about late frosts. Can anyone suggest weather or not it’s safe to plant them out now.

 

When I lived in Essex I grew them as a hardy annual, direct sowing.
Here in Devon until a few years ago there were lot of these growing on a verge and I assumed hey just self seeded and then the house changed hands and they disappeared a year or so later.

 

They tend to self seed in sandy soils, where they can overwinter.
If they are hardened off I'd get them in the ground ASAP, as they grow tap roots to do well.

I stress they need to be hardened off.

 

Thanks both. Obviously I need to get the balance just right between fully hardened off, avoiding damaging frost and missing the pre taproot window. Think I’ll give them another week so they can be popped back in the cold frame if necessary. Meanwhile they are being blown about by near gale force winds today.

 

Self seeders here too.