Hollyhock (Alcea rosea) – Zones 3 to 9. These old- fashioned favorites unfurl richly colored single or double flowers on lanky stems that can reach 9 feet in height. They can tower above a garden, adding a lovely vertical element to your yard.
Hollyhock is a biennial, which means it grows foliage on short stems its first year but doesn’t flower until the following year. Growing hollyhocks in the garden is the goal of many gardeners who remember these impressive flowers from their youth. It is a favorite ‘cottage garden’ choice in my yard.
Did you know, based on folklore, that hollyhocks were planted near outhouses so ladies wouldn’t have to broach the unmentionable subject of outhouses in a Victorian household? They could simply look for the hollyhocks themselves.
Hollyhocks need full sun and moist, rich, well-drained soil. The mistake many novice hollyhock growers make is to plant this flower in soil that is too dry. If you are planting seeds, sow the seeds outside about a week before last frost. If you are planting seedlings, wait about two to three weeks after last frost. Hollyhock seeds only need to be planted right below the soil, no more than 1/4- inch deep. Hollyhock plants should be about 2 feet apart to grow well. You can also plant bare root hollyhocks.
Hollyhocks are a short lived perennial. This means that most varieties will only live two to three years. Their lifespan can be extended some by removing growing hollyhock flowers as soon as they fade. By living in a non-tropical region, cutting them
back to the ground and mulching them will also help.
The one benefit that comes from growing hollyhock flowers is that they easily reseed themselves. While they may be short-lived, in their proper growing conditions they will continually grow more, which will keep the hollyhock flowers consistent in years to come.
Few diseases affect hollyhocks; however, hollyhock rust is a problem. Rust is a common and serious disease that is found in hollyhock gardens and is spread by mallow, which is a weed that acts as a disease reservoir. The rust disease is a fungus that spreads by rain droplets splashing on leaves and through air transfer. If not treated, the disease intensifies through summer and will eventually kill the plant. Rust will overwinter and infect the crowns of sprouting plants in spring.
The rust disease in hollyhocks appears as rust-colored bumps on the underside of the leaves and stems of the plant. The disease starts as small rust flecks and grows into raised bumps or pustules that will spread to all parts of the plant greens. An infected plant will appear limp and ragged. Does hollyhock rust spread to other plants? Yes, it does! It only spreads to other members of the Alcea family, so most of your other garden plants are safe.
There are a few pests that affect hollyhocks: The Hollyhock weevil (Apion longirostre) is one of them. The hollyhock weevil is commonly responsible for damaged foliage and thinned-out stands of hollyhock. Another is the Japanese beetle (Popillia japonica) which feed on hollyhock leaves as adults, causing the foliage to turn brown from the top of the plant down. The Hollyhock Sawfly larvae (Neoptilia malvacearum) feed extensively on leaves, eventually skeletonizing hollyhock foliage. Spider mites such as the Two-Spotted spider mite (Tetranychus urticae) feed on hollyhocks. Spider mite feeding damage appears as stippling or flecking on leaves, leaf yellowing and premature leaf drop. Mites are small, barely visible to the naked eye, and they prefer hot, dry conditions; the presence of fine webbing indicates a severe infestation.
Some additional possible pests: multiple species of thrips including gladiolius thrips can affect hollyhocks. These small, flying insects pierce flowers, buds, leaves and stems, causing the appearance of silvery, necrotic lines and sometimes dieback. Avoid the use of broad-spectrum insecticides that could harm natural thrips predators. Leafhoppers and aphids may also occasionally act as hollyhock pests. Aphids are soft-bodied insects that tend to feed on vulnerable new growth. There are plenty of resources available to learn more about the various pests that can affect hollyhocks. I would encourage you to further your research if you find you are having issues with your hollyhocks!
If anyone would like some seeds I have some single-flower black, white, red and Crème de Cassis seeds I’d love to share with fellow gardeners. I am looking for single-flower variety in a bright yellow, if anyone has them growing in their yards! I can leave some at Amy’s office if there is an interest.
Resources and further reading: https://www.gardeningknowhow.com/ornamental/flowers/hollyhock/tips-on-hollyhocksgrowing-hollyhocks-successfully.htm
Submitted by Tracy Livingston