Propagate by seed, division or separation – Seed may not breed true.
Germination temperature: 70 F to 80 F
Days to emergence: 8 to 12
Seed can be saved 6 years.
Plant root divisions (basal stem pieces with attached roots) after last frost, 2 to 3 feet apart in rows 2.5 to 3 feet apart.Planting from seed not recommended because results are highly variable and usually inferior to parent plants. But if you do, start seeds about 8 to 12 weeks before last frost. Harden off in cold frame. Cold treatment of starts (keeping temperature between 35 F and 50 F for about 10 days) can induce flowering in first-year plants. Transplant outside after soil has reached 60 F.
Benefits from the use of a low-nitrogen fertilizer (high in phosphorus and potassium), which can be incorporated before planting.
Plants usually don’t flower the first year.
To increase chance of overwintering, head back to 12 inches and cover with leaves, covered with baskets or boxes, and heap more leaves over the top of the basket. Another alternative is to dig roots and store in a cold (but not freezing) room. Pot up about a month before transplanting out after last frost.
While individual plants may live up to 15 years or more, divide about every 3 years to keep planting productive.