• Scientific Name: Alcea rosea
  • Synonym: Althaea rosea
• From the Greek: althaia (to cure)
  • due to the medicinal qualities of some species
• Family: Malvaceae
• USDA Hardiness Zones: 2-8
• Type: herbaceous perennial, annual or biennial

The Garden Hollyhock (Althaea rosea Cav.) is one of the oldest plants in cultivation, having been found in Chinese gardens by the earliest European visitors. Gardens of yesterday were not complete without the tall flowering spires of this easy-to-grow plant.

Hollyhocks grow to heights of five to eight feet or more, flowering along straight stems between June and August. Pinching one or two times early in the growing season gives shorter, plants with more branches. The individual flowers are bell-shaped, 3 ½ inches (8 cm) and more in width, with separate petals of vivid colors from white through pink to scarlet and the deepest maroon. The cultivar `Nigra' is called the Chocolate Hollyhock due to its dark chocolate blossoms. There are double, ruffled begonia-like flowers as well as single forms with five petals. Petals may be smooth or lightly fringed. The leaves are rough-textured and may be up to 10 inches across.

Alcea rosea probably originated in Asia Minor. While originally a perennial, this plant is used as an annual, biennial, and perennial in today's gardens. In northern areas of the county the hollyhock is treated as an annual, but usually will survive and bloom the second year if provided winter protection. In Grand Junction, I have had Hollyhocks come back for several years and become taller and more striking each year. A layer of mulch over the plants for winter protection as well as winter watering certainly helps.

Perennial and biennial forms develop a rosette of ground-hugging leaves the first year. One to several flower stalks develop the following year(s). The hollyhock readily self-seeds and may become a nuisance if seedlings are not culled from the garden.

Annual forms exist to include 'Indian Spring', `Summer Carnival', `Silver Puffs', `Majorette' and `Pinafore'. These are reported to produce flowers the first year they are seeded.

This plant is effective as a background plant against a building or fence where it is protected from wind. Hollyhock is also useful in mass plantings to provide screening. In windy sites, staking will be required. Plants are short lived perennials especially in wet, poorly drained soil and are treated as biennials, although self seeding reproduces them well.

Hollyhocks prefer a rich soil with lots of organic matter and a warm sunny location. They require full sun as the plant dislikes any amount of shade. Over watering creates more problems with diseases and will result in a shortened plant life.

Propagation is usually by seeds, which should be sown an eighth of an inch deep. Seed can be started in a greenhouse eight weeks prior to the last spring frost. A germination temperature of 72o Fahrenheit (22C) will result in germination within five to ten days. Plants are then set into the garden at the same time as the last spring frost. The hollyhocks do not transplant easily.

Seed can be sown directly into the garden two weeks before the average last spring frost. Seed will normally germinate in 10 to 14 days.

Transplanting is best done in the spring taking care to avoid plant damage. The roots are large and the growth is from a few strong buds at the crown. If planted in the fall in areas where frost heaving is a problem the plants may heave out of the ground and plant death may result. Applying a three to four inch layer of mulch over the plants after the ground has frozen in the fall will help reduce this problem.

The common garden hollyhock (Alcea rosea) is one of approximately 60 species of Alcea originating from temperate Europe and Asia. Alcea ficifolia, a perennial hollyhock from Siberia, has been crossed with Alcea rosea to create more vigorous, healthier perennial hybrid plants.

Hollyhock Rust (Puccinia malvacearum) causes formation of round swellings or bumps on the undersides of the leaves. Rust infects leaves, stems, bracts and other green plant parts. Brown pinhead size spots develop on the undersides of leaves. On the upper leaf surface the spots are larger, bright yellow or orange with reddish centers. The spots run together causing death of large leaf areas. Ash gray pustules form on the lower leaf surfaces during rainy weather. Remove infected leaves when first noticed. This fungus survives on old plant debris so it is important to destroy old plant parts at the end of the growing season. Fungicide sprays are available which help manage this disease problem.

The hollyhock weevil (Apion longirostre) is a snout beetle approximately three-eights inch (5 mm)long. With a long snout it eats holes in leaves and damages flower buds and seeds. The female weevil has the longest snout and chews holes in developing buds in which to lay eggs. The grub stage of this insect feeds on the developing seeds. Pupation takes place within the seed. In Colorado, some adults emerge in August and September while the remainder stay within the seed and emerge the following spring. There is one generation of weevils each year.

Lace bugs suck sap from the underside of leaves which are covered with brown specks of excrement. This insect is a beautiful small bug with transparent wings reticulated or netted in a lacelike effect. The head is covered with a hood.

Other insects reported as problems on the Hollyhock include:

• Aphids
• Beetles
• Japanese
• Oriental
• Rose Chafer
• Spotted Cucumber
• Borers
  • burdock
  • European Corn
  • Stalk
• Bugs
  • Hollyhock Plant Bug
  • Tarnished Plant Bug
• Butterflies
  • Painted Beauty
  • Painted Lady
• Caterpillar
  • Yellow Wollybear
• Leaf miner
• Leaf Roller
• Leaf Skeletonizer
• Mealybug
• Mite
  • two spotted
• Moth
  • Abutilon
• Scale
  • Brown Scale
  • Latania
  • Lesser Snow
• Slug
  • Spotted Garden
• Thrips
  • Gladiolus
  • Hollyhock
• Weevil
  • Boll

Viruses are also reported to be a problem with hollyhock. More information on hollyhock viruses can be found at http://biology.anu.edu.au/Groups/MES/vide/famly082.htm#Althaea rosea. A link to this site is provided in the following list of references.

Reference:

Bennett, J. and Forsyth, T. 1994. The Harrowsmith Annual Garden. Camden House Publishing
Cranshaw, W. 1992. Pests of the West. Fulcrum Publishing, Golden, Colorado
Jelitto, L. And Schacht, W. 1990. Hardy Herbaceous Perennials. Timber Press, Portland Oregon.
Marston, T. (Ed.) 1993. Annuals. Hearst Books.
Nau, J. 1996. Ball Perennial Manual: propagation and Production. Ball Publishing, Batavia, Illinois
Sara, D. (Ed.) 1960. The New American Garden Book, Books Inc. New York.
Westcott, C. 1973. The Gardener's Bug Book: fourth edition. Doubleday.

Internet sites with additional information include:
viruses

The `Gardens at the Mesa County Extension Office'