Hollyhocks (Alcea rosea) are tall, old-fashioned flowering plants often associated with cottage gardens. Many common varieties are biennials, establishing foliage in the first year and flowering in the second before dying. Others are short-lived perennials that can return for several years. Propagation is achieved through seeds, cuttings, or division.
Timing and Seed Preparation
The optimal time for collecting hollyhock seeds is late summer or early fall, after the flower stalks have faded and the seed cases have turned brown and dry. Harvest the seeds before the cases naturally split open, and store them in a cool, dry place until ready for planting. For perennial varieties, the seeds can be sown immediately, as they may benefit from cold stratification to aid germination.
The best time to sow for flowering the following year is late summer or early fall, allowing the young plants to establish a strong root system before winter. Starting seeds indoors is typically done in early spring, about nine weeks before the last expected frost date, which provides a head start. If propagating via cuttings or division, select a healthy parent plant free of rust, and schedule this process for the spring when the plant is actively pushing new growth.
Propagating Hollyhocks from Seed
Seed propagation offers the highest success rate, though hybrid varieties may not grow true to the parent plant. To improve germination, soak the seeds in warm water for 12 to 24 hours to soften the hard outer seed coat. For indoor starts, use individual, tall pots filled with a fine, well-draining seed-starting mix, as hollyhocks develop a deep taproot easily damaged during transplanting.
Sow the seeds by pressing them lightly onto the surface of the moist compost, covering them with only a thin layer of fine soil, or none at all, as they often require light to germinate. Place the trays in a warm location (15°C to 20°C); germination should occur within two weeks. Once the seedlings develop their first true leaves, they are ready to be “pricked out” and moved into larger containers. Handle them carefully by the seed leaves, avoiding the delicate stem.
Direct sowing outdoors should be done in early spring, about one week before the last expected frost date. Prepare the soil by loosening it and clearing any weeds, then scatter the seeds and lightly compress them into the soil surface. Space the seeds about 60 centimeters apart for mature plants, or sow them more closely and thin out the weaker seedlings later to ensure good air circulation. Consistent moisture is important until the seeds germinate and establish a root system.
Propagating Through Cuttings or Division
Cuttings and division allow for cloning the parent plant, which is useful to maintain a specific color or form. Division is generally only feasible for true perennial hollyhock varieties and is best done in the spring before new growth is too advanced. Because the plant has a deep, thick taproot, division is difficult; dig up the entire root ball and use a sharp knife to cut it into sections. Each resulting section needs at least one growing point, or “eye,” and a healthy piece of the taproot attached to be viable.
For cuttings, take basal cuttings—young, non-flowering stems that emerge from the base of the plant in the spring. Cut the stem as close to the ground as possible, remove lower leaves, and dip the cut end in a rooting hormone. Plant the cutting into a pot filled with well-draining cuttings compost, ensuring the lowest remaining leaves sit just above the soil surface. Cover the pot with a clear plastic bag or place it in a closed propagator to create the high humidity necessary for roots to form over the next few weeks.
Initial Care After Propagation
Careful initial care is necessary to ensure the survival and establishment of new plants. For seedlings started indoors, “hardening off” is required, which involves gradually exposing them to outdoor conditions over a week or two before final transplanting. The chosen final location should provide at least six hours of direct sunlight daily and feature rich, well-draining soil, ideally against a wall or fence to provide support for the tall flower stalks.
Young plants require regular watering to keep the top 15 centimeters of soil consistently moist until they are well-established. Watering at the soil level, rather than overhead, helps prevent fungal issues like hollyhock rust, which can quickly damage the foliage. Young plants are susceptible to slugs and caterpillars, so monitor them closely and protect the new growth during their early stages.