It may not seem to be a candidate for a hardy plant, but hardy it is! Give it a warm sunny spot and moisture retentive soil and it will develop leaves up to 2 feet, 60cm, long and grow up to 4 foot, 120cm, tall. Give a dry mulch in winter to protect from hard frosts To avoid possible winter rot I would not overwinter as a marginal plant. If growing as a marginal plant then lift and treat as a dahlia bulb.