Blacknight hollyhock is a first year-flowering, true perennial hollyhock to 5-6 ft. tall and up to 5 ft. across. Large single flowers of the deepest purple-black appear from late spring through early fall. Plants are winter hardy to zone 3.
Grow Blacknight hollyhock with Soulmate butterfly weed.
Growing Blacknight Hollyhock Seeds
Plant Hollyhock Seeds: Sow seeds in 2 in. pots or cell packs, press into soil and lightly cover. Kept at 70-75° F., germination is in 14-28 days. Can direct sow into prepared seed beds in groups of 3-4 seeds, spaced 2-3 ft. apart. Thin to strongest plant.
Grow Hollyhock: Full sun, part sun in hottest climates. Hollyhock plants perform best in fertile soil with regular moisture. Irrigate from below and provide good air circulation. True perennial hollyhocks noted in description. Most are biennials, or short-lived perennials. Many hollyhocks flower the first season when started early. After flowering cut back plants hard, to within a few in. of the ground. Continue to water and fertilize. Plants repeat bloom in late summer and fall. Single flower hollyhocks attract hummingbirds and butterflies. Hollyhock plants will often self sow.
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We guarantee all the seeds we sell for one full year from the date of purchase. If you are unsatisfied with any seeds purchased from Swallowtail Garden Seeds, we will issue a refund. For customers in the U.S., we can send one-time replacements or issue a refund.