Hollyhocks grow from USDA zones 3 to 8 as biennials, meaning they live approximately two years. However, if cared for properly, hollyhocks can be annuals in colder climates and short-lived perennials in warmer climates. They can grow to heights of 10 feet in some gardens, and their blooms come in many colors. Hollyhocks flower in the summer and can keep flowering if you deadhead old blooms. They also reseed vigorously if allowed.
Plant hollyhocks in full sun. They can grow in any type of soil, but it must be well drained. They will grow best in moist soil, but they can tolerate dry soil as well, if needed.
Water hollyhocks until the soil is moist throughout the spring and summer while they are growing. Water them two to three times a week or enough to keep the soil from drying out completely.
Fertilize hollyhocks with compost or manure several times during their growing season, once in early spring, once in late spring and once in early summer. Apply the compost or manure to the base of the hollyhocks and cover it will mulch.
Deadhead the flowers as they fade. This will allow the hollyhocks to grow more flowers and keep them from going to seed.
Cut the stalks of the hollyhocks down to 5 or 6 inches above the ground once they stop flowering. Mulch over the hollyhocks once the ground freezes. This will allow them to come back the following year.