Description
Best grown in light, medium moisture, organically rich, well-drained loams in full sun to part shade. Avoid wet or poorly-drained soils. ‘Astra Semi-Double Blue’ is easily grown from seed. Division and transplanting are possible but tricky because of the fragile, fleshy root systems of these plants, and it is probably best to leave plants undisturbed once established. Deadheading spent flowers generally prolongs the bloom period. New season plant stems emerge late in spring, so gardeners must be careful not to damage crowns by early cultivation (leaving old plant stems in place throughout winter to the point when the new growth first appears helps mark plant locations). Staking is usually not necessary because of the short stems of this compact cultivar. (Courtesy of Missouri Botanical Gardens Plant Finder)
