When to Plant Hollyhock Seeds

Hollyhocks, once grown along white picket fences throughout the U.S., are making a comeback as interest in cottage gardening grows. They are tough plants, hardy between U.S. Department of Agriculture plant hardiness zones 3 through 8. They grow well from seeds, or buy potted nursery plants.

Hollyhocks are biennial plants that bloom profusely the second season before dying. They regrow from seeds left behind by the dying plants, making them seem like perennials. Plant them in May after the last frost through September, to imitate the natural process of reseeding. The seeds germinate in two to three weeks at temperatures above 60 degrees F.

Hollyhocks thrive in full sun, in fertile, well-drained soil. They prefer moist soils but will tolerate drought conditions. Mulch hollyhocks in fall with 2 to 3 inches of wood chips, straw or compost to protect young plants from freezing temperatures. Some gardeners prefer to start hollyhocks indoors six weeks before the last expected frost. They germinate well in garden soil, though.

Old-fashioned varieties rarely bloom the first season, although newer varieties are bred to bloom more. The second season, hollyhocks bloom from June to September. The plants come in a variety of colors, such as white, pink, yellow, red, burgundy and wine. Double-flowered varieties produce large blooms with two layers of petals. Try single color varieties, such as 'Peaches 'n' Dreams,' or a variety that produces blooms in several colors, such as 'Country Garden Mix.'

Hollyhocks are vulnerable to several diseases and pests. Rust causes yellow or orange pustules on the leaves, but rarely affects the blossoms. Control it by destroying all affected leaves or spray with a fungicide. Spider mites, caterpillars and Japanese beetles nibble on the leaves, but usually don't harm the flowers. Plant hollyhocks at the back of the garden so shorter plants hide the messy leaves but leave the blooms visible, or spray the plants with an insecticidal spray.