You could throw a blanket over them for additional protection.

Snow is a good insulator. You should be fine.

Thank you both for your replies

The Lupines will be okay, they are very hardy and can tolerate a hard frost. When I sow them they are always among the first seeds to sprout.

Not sure about Delphs.

The situations of most concerns in Winter Sowing, are killer frosts, If it''s hot outside, open up the containers and slugs. Put sluggo or some kind of slug bait down. They can wreck havoc on your seedlings.

Now, my garland daisies are sprouting lol.

If this is you're first year of WSing, then you must CELEBRATE your seed germination, not worry about them!!!! If you were going to get a prolnged period of deep cold (like in January), maybe then be worried about sprouts. But we are headed into March, your perennial sprouts in covered jugs should be fine.

thanks for the advice nan. Less worrying and more celebrating! *Pops Champagne*