Begonia and buzy lizzies are half hardy annuals, and will be killed off by any frost. leave planting out until mid may if you,re in a warmer part of the uk, end of may or early june if in a colder part

It's too early and a sudden frost will kill them. You need to wait a few weeks until the danger of any frosts has gone.

I'm in Cornwall, a couple of hundred yards from the sea. I've been hardening off my Busy Lizzies near the house and planted some out today - but I do know I'm taking a risk doing it. We haven't had any frost for about three months so I reckon the gamble is worth it.