Ideal Temperature to Sprout Hollyhock Seeds

Ideal Outdoor Temperatures

Sow hollyhock seeds in the mid to late summer to enjoy plenty of beautiful blooms the following year. To ensure suitable temperatures for germination, the University of Illinois Extension recommends sowing hollyhock seeds in June, July or August. Wait until temperatures are consistently between 75 and 85 degrees F. before sowing the seeds in your garden or home landscape. Seeds planted in soils that have warmed to 60 to 72 degrees F. will sprout in just over a week.

Hollyhocks need plenty of warm, direct sunlight and fertile, well-draining soil to thrive. Sow your hollyhock seeds in a location that receives six or more hours of direct sunlight each day. If necessary, work equal parts peat moss, compost and coarse horticultural sand into the soil to a depth of 4 inches to improve its drainage. Broadcast the seeds over the planting site and cover them with a 1/4-inch soil. Maintain lightly moist soil to promote germination; after the seeds sprout, continue to water as often as necessary to prevent the soil from drying. Fertilize hollyhocks in the early spring with a balanced, water soluble-fertilizer for vigorous summer blooming.

Hollyhock seeds can be germinated indoors in a shallow planting tray and transplanted to your garden or home landscape as seedlings. Choose a planting tray with adequate drainage holes and fill it with a peat-based growing medium. Plant the seeds in the planting tray no deeper than a 1/4-inch. Moisten the growing medium slightly to urge the seeds to sprout. Place the tray near a sunny window that receives direct sunlight for at least six hours a day. Set your thermostat to keep the temperature of the room between 70 and 80 degrees F, or use a plant heating mat under the tray.

Transplant the hollyhock seedlings to your garden or home landscape when they are 4 to 6 inches tall. Choose a full-sun planting site will fertile, well-draining soil. Unsuitable soils can be improved with organic materials such as peat moss, compost and coarse, horticultural sand; incorporate the organic matter into the top 6 inches of soil. Plant your hollyhock seedlings at the same height that they were growing in the planting tray.