Get them in the ground! Safer there, and a mulch of something like garden compost will protect them over winter and feed them for the next season. Are you north or south?

Ive planted lots of herbaceous over the past few years, including some lovely Heleniums, and i've found that they seem to do better planted late spring, early summer....providing you can get enough water on them

they ten readily available at garden centre chains even B&Q. failing that then mail order at companies like Hayloft plants, Crocus etc.

Thankyou.