You might be OK with the Verbena left outside. I cover them with a thick layer of newspapers and a potfull of spent compost and they have survived the winters. They tend to come up quite late in spring. This year I covered them with a clouch and it did the trick. Like Christopher2, I take cuttings as well but haven't found any seedlings so far(must be doing something wrong)
As a matter of interest, does anyone grow wild garlic?
So muh depends upon the amount of frost we get - until 2 years ago I left alot of things outside but after that killer winter I bring into the greenhouse alot more than I used to do. Alliums are fine out there, as are lilies, but blue salvias, chocolate cosmos (not the annuals) need bringing in, as do geraniums, not the scrambers, they stay out and are fine, but the pelargoniums. Fuschias, some potted pinks, agapanthus in pots, various other tender things come in when the night temeratures drop enough for a grass frost. I keep the greenhouse around 5 degrees when it freezes, with an electric heater. Anything that needs more than that just has to take its chances.
Thanks for all your posts and advice! Really appreciate your advice. No wild garlic for me, jatnikapyar...