How Tall Do Hollyhocks Get?

Hollyhocks, a cottage-garden favorite, come in a wide variety of colors, flower forms and heights and traditionally were planted to camouflage outhouses. They are biennials, which means they grow leaves and roots the first year, then flower and produce seed the second year. Deer dislike their flavor, but hummingbirds love them.

Most old-fashioned hollyhocks, Alcea rosea, grow 6 to 10 feet tall and flower from June through August. The tallest hollyhock, as reported in the 2004 edition of "Guinness Book of World Records," was 19 feet, 7 inches, grown by George Palmer in 1978 in England. Dwarf varieties, such as Alcea rosea Majorette Mix, grow 2 to 3 feet tall.

Plant seeds in full sun in early spring. Get flowers the first year by planting nursery plants or starting seeds indoors eight weeks before last frost. In U.S. Department of Agriculture climate zones 7 and above, plant seeds outdoors in August for bloom the following summer. Let hollyhocks ripen and drop their seed for new plants each year. Or cut the stalks after bloom to produce a second flowering from the same plant in fall.

Rust, a fungus characterized by orange pustules on leaves and stems, is the most common disease for hollyhocks. Help prevent it by watering only at the soil level, not overhead. Spray the leaves (especially the undersides) and stems with a copper-based fungicide every 10 days before rust starts.

Alcea nigra has single, dark-purple blooms and grows 3 to 6 feet tall. Alcea pallida grows 5 feet tall and is a Turkish species with small, single lavender blooms. Alcea rugosa, a Russian variety, grows 7 feet tall, with large, single, pale yellow blooms. It is rust resistant.