These plants will die at temperatures from -5degC and below. Damage will occur at -3deg C, so yes, they need to be kept frost free.

thanks bamboo other question i forgot was when they actually grow.do you cut them back after they have finished and how much do i cut them
doug

Pruning advice is just to remove spent flower stems to encourage more flowers, so presumably in the growing season. Handle with care though - this plant is considered toxic, may cause skin and eye reactions, so best to handle with gloves, skin and eye protection.

They may need support - mine tend to flop over. Even though they are listed as a biennial, mine take 3 years to flower. Also, mine that flowered this year have new growth and will flower again next year. Cut the stems just behind the last flower that opened to get a smaller 2nd flush. It is so much that the plant is toxic, but rather the fine hairs that are really annoying to unprotected skin.

thankyou to both of you for the advice many thanks
as i said i have never grown them before i'm always looking for a new challenge to see what can grow in my garden
doug