Common Problems To Avoid When Growing Hollyhocks

Hollyhocks are wonderful summer-blooming flowers that look right at home in cottage gardens and perennial borders. These tall, colorful flowers are easy to grow, and their stately height is useful for adding privacy to your yard. They can bloom the first year they're planted from seed in spring, depending on variety and growing conditions. The size of these flowers makes them fairly robust, but they do have a few potential issues. Don't worry! We have a few tips to help you avoid common problems when growing hollyhocks.

To avoid common problems with these old-fashioned, beloved flowers, there are some things you should know before planting hollyhocks. They do best with full sun and well-drained soil. Because they're biennial, planting seeds or new plants every year helps ensure you have some hollyhocks in your garden consistently. They are somewhat short-lived, so regular planting also replaces the gorgeous flowers that die before you get your summer garden.

Adding hollyhocks to the garden can add dramatic height to your flower bed, but their size can pose challenges, too. The poet T. S. Eliot mentioned "hollyhocks that aim too high" in "East Coker," one of his famous Four Quartets. Indeed, their height makes them susceptible to flopping over sometimes. To avoid this problem, there are three preventive approaches. First, plant them in full sun so the stalks grow strong enough to support the large flowers. Second, make sure they're sheltered from high wind. Third, plant your hollyhocks near a wall or fence for support. You can also try simple staking methods, like those used for taller dahlias or delphiniums, to support hollyhocks and keep them from drooping.

Hollyhocks are not only very tall, but they have very large leaves and are wide at the base. So even though they look like slender flowers, they need a lot of room in the garden. One important reason to give them some space is to provide adequate airflow. Not getting enough airflow can cause problems, including diseases such as powdery mildew or hollyhock rust. 

Powdery mildew on hollyhocks is a fungal growth that leaves a white chalky film on the leaves, stems, and sometimes flower buds. Hollyhock rust is also a fungal disease, caused by the fungus Puccinia malvacearum, which affects plants in the Alcea or mallow family, including mallow and hollyhocks. Rust causes tiny brown spots to appear on the undersides of hollyhock leaves, and eventually can weaken leaves and cause them to fall off. 

Both of these problems are exacerbated by high humidity and lack of airflow and treating fungal disease on plants is time-consuming, so prevention is the best approach. In addition to making sure the plants have space around them when planted, keep improving airflow by making sure the garden is weeded regularly and dividing perennials frequently to keep overgrown clumps under control. To cut down on too much humidity, try watering at the base of the plant instead of from overhead. Also, be sure your hollyhocks get plenty of sun, which can help prevent fungal diseases.

Hollyhocks love sunshine and require regular watering to stay healthy. The summer sunlight stimulates growth, and hollyhocks form buds quickly and flower profusely in summer. However, sometimes summer heat can cause hollyhock flowers to wilt. Hot weather can also stimulate fast growth, demanding energy from the hollyhock while promoting weed growth that may compete for soil nutrients. Both of these situations also cause the flowers to look a bit sad and droopy. There are several ways to prevent this problem.

One way to keep your hollyhocks from succumbing to heat is to put a light layer of natural mulch around the base of the flower. Shredded pine bark is a perfect mulch for this; it helps retain moisture and keeps temperatures even. The mulch will also help prevent too many weeds from growing.  Also, when watering your hollyhocks, water at the base of the plant, and the mulch will help distribute and conserve that moisture. 

Another tip for preventing the problem of drooping or sad-looking hollyhock flowers is to deadhead the flower stalks regularly. Remove any spent blooms, damaged leaves, or broken stems. This not only keeps the plant looking neat but helps prevent the hollyhock from setting seed. This allows the plant to redirect its energy to flowering. However, if you want your hollyhock to reseed in the garden, be sure to leave a few blooms intact at the end of the season to go to seed.