Although you might admire the colorful pink, purple, red, yellow or white blossoms of a standard perennial hollyhock (Alcea rosea), they grow 6 to 8 feet high, far too large for many urban gardens. However, there are a limited number of miniature or dwarf hollyhock cultivars that you can plant in a flowerbed or flanking a patio or sidewalk. Their seeds are planted the same way as standard cultivars, and they can be grown in U.S. Department of Agriculture plant hardiness zones 3 through 9.
When to Plant
The best time to sow perennial hollyhock seeds is midsummer, giving them time to mature before they go dormant in winter; they will blossom the following spring. Alternatively, you can plant the seeds in a nursery bed in midsummer and transplant them the next spring. If you plant them in early spring, there is a chance they will bloom later in the summer. If you sow the seeds in spring, plant the seeds indoors in pots two to three weeks before you expect the last spring frost. Transplant them when the danger of frost has passed. Annual miniature hollyhocks are planted in the spring.
Planting as Biennials
Perennial hollyhocks don’t bloom well after their second year. If they’re more than one year old, they’re prone to infection by hollyhock rust, a fungal disease. Lemon-yellow to orange splotches that grow darker appear on the bottoms of hollyhock leaves eventually destroying them. After they flower, infected hollyhocks have to be removed. Because of their flowering decline and susceptibility to hollyhock disease, growers typically treat hollyhocks as annuals or biennials and plant new seeds every one or two years.
Planting Perennial Miniatures
“Queeny Purple” (A. rosea “Queeny Purple”) grows from 20 to 29 inches high, the smallest of the dwarf hollyhocks. “Marjorette Mix” (A. rosea “Marjorette Mix”) grows from 24 to 30 inches high. Plant the seeds in well-drained soil in summer until early fall at least two months before you expect the first frost. They like full sun. Light aids their germination, so leave seeds on top of the ground. They should germinate in 10 to 14 days.
Planting Annual Miniatures
“Spring Celebrity” (A. rosea “Spring Celebrity”) grows from 24 to 32 inches with blossoms in a wide range of colors. Plant the seeds 1/4- to 1/2-inch deep in spring after the danger of frost has passed. Planted at a temperature of 72 to 74 F, they take eight to 10 days to germinate, and the plants should blossom after 105 to 119 days.