How to Grow and Care For Common Hollyhock (Alcea Rosea)

How to Grow and Care For Common Hollyhock (Alcea Rosea)

Image by Stan Shebs from wikimedia

Hollyhocks (Alcea rosea), a classic cottage garden staple, bloom in midsummer with numerous flowers on tall spikes. The majority of the most popular varieties are biennials, meaning they only last two years. The first year is spent on foliage growth and energy storage. The stalks sprout, flowers bloom, and seeds form in the second year. Many varieties, however, behave like short-lived perennials and will flower in their first year if planted early enough in spring or started indoors in winter.

This traditional garden favourite can reach 8 feet in height and has large, heart-shaped foliage and long-blooming ornamental flowers. This biennial herbaceous plant adds a lot of interest and self-seeds readily, providing new growth year after year. When growing from seed, you can plant hollyhocks in late summer and they will bloom the following year.

How to Plant Hollyhocks

Hollyhocks can be easily grown from seeds both inside and outside. A week or so before the last frost, seeds can be directly planted outside. Just 1/4 inch deep and about 2 feet apart, sow. Because of their long taproots, hollyhocks should be started indoors in tall, individual pots and transplanted as soon as possible to prevent damage. 9 weeks before the last average frost date, start indoor seedlings. After the last frost, seedlings can be transplanted outdoors two to three weeks later. Remember that some plants are biennials and might not bloom until their second year.

Where to plant

Plant in full sun to partial shade in a well-draining area. Because of their height, shield them from wind-related harm and offer support with a fence, wall, trellis, or stake. If left to their own devices, hollyhocks will readily self-seed; therefore, plant them in a location where this won’t be an inconvenience. Hollyhocks are also among the few plants that can be grown close to black walnut trees because they can withstand the chemical juglone that the tree leaches into the soil.

Common Hollyhock Care

These hardy plants can thrive in a variety of environments, but they dislike moist winter soils. When planted in a protected area, hollyhocks have strong, sturdy stems that can stand upright without staking. This traditional favourite, which has large, showy blooms in a variety of colours, is attractive when planted along a fence or wall or at the back of a border. When planting, place your common hollyhocks sufficiently apart to encourage good air circulation and lessen issues with the fungal disease rust. It should be sufficient to space them apart by about 18 inches.

Location

The flower prefers a location with lots of exposure to sunlight in order to grow tall and healthily. It also adapts to partially shaded areas. The flower also favours locations that are wind-sheltered. Because of its height, it needs a secure area. Fixate on plants that grow particularly tall. If you plant hollyhocks on the south side of flower beds or on house walls, they will grow profusely and have full blossoms.

Soil

Common hollyhocks are popular because they grow well in a variety of soils. Your plants should still thrive in poor soils as long as you enrich them with organic matter because they prefer fertile, heavy soils.

Water

Maintain soil moisture and provide routine irrigation for hollyhock seedlings. They are somewhat drought tolerant once they have established themselves, though. When watering, avoid wetting the foliage as this can result in diseased leaves.

Temperature and Humidity

Hollyhocks can withstand temperatures as low as 5 degrees Fahrenheit. Early frosts, however, can harm the flowers. For flowering plants, daytime temperatures between 65 and 70 degrees Fahrenheit are ideal.

Hollyhock rust problems can be brought on by excessive humidity.

Fertilizer

One of the most crucial maintenance factors for common hollyhocks is their nutrient content. These plants are heavy feeders and adore fertile environments. Bigger flowers and healthier foliage will result from adding organic matter to your soil in the spring and applying an organic flower fertiliser or fish emulsion with a high nitrogen content every few weeks during the bloom period. The plant’s leaves may turn yellow, and the blooms may be underwhelming due to low nutrient levels.

Pruning Hollyhocks

If seed is to be collected, cut back flower stems after flowering. Remove any leaves that have been severely rusted.

Propagation

Hollyhocks are best and easiest to grow from seed, and if the flower stalks are left in place, they will readily self-seed.

Over-wintering

Hollyhocks can be grown as annuals in hard freeze zones by starting seeds in containers and overwintering indoors. Water sparingly during the winter and gradually reintroduce them outside as the weather warms.

In other areas where they can be left outside, prune them back in the fall to about 6 inches above ground level. Cover the root zone and base of the plant with 4 to 6 inches of straw or mulch. Remove in layers in the spring to gradually acclimate the roots. Remove all of the straw or mulch once new growth appears. In case of a spring freeze, re-cover.

Common Pests & Plant Diseases

Rust is a fungal disease that can cause significant damage to the foliage, resulting in premature leaf drop and stunted growth. Removing the leaves on the lower part of the plant stem, cutting back the plants in the fall, and promptly removing debris will help to reduce fungus problems and spread.

Japanese beetles and spider mites may also be attracted to your common hollyhock, and young growth is a tasty treat for slugs.