How to Grow Common Hollyhock (Alcea Rosea)

Pink flowers of the common hollyhock (Alcea rosea)

Thanit Weerawan / Getty Images

If you are looking for a flower to add to a charming cottage garden, look no further than the common hollyhock (Alcea rosea). This traditional garden favorite can grow up to 8 feet tall but is strong enough that it still might not need staking.

The large, heart-shaped foliage and long-blooming ornamental flowers of these short-lived perennial or biennial herbaceous plants add plenty of interest, and they readily self-seed to provide new growth year after year. You can plant them in late summer when growing from seed, and they will bloom the following year.

 Botanical Name Alcea rosea
Common Name Common hollyhock
 Family Malvaceae
 Plant Type Perennial, Herbaceous
 Mature Size 6-8 ft. tall, 1 to 2 ft. wide
 Sun Exposure Full sun
 Soil Type Moist, Well-drained
 Soil pH Acid, Neutral, Alkaline
 Bloom Time Summer
 Flower Color White, Pink, Red, Yellow, Lavender
Hardiness Zones  2-10, USA
 Native Area Turkey

Common Hollyhock Care

These adaptable plants can grow in a range of conditions but aren't fans of wet winter soils. Select a sheltered site to minimize the chances of the tall plants facing damage or requiring staking. Space your common hollyhocks far enough apart when planting to promote good air circulation and reduce problems with the fungal disease rust. Positioning them around 18 inches apart should be adequate.

Light

Although common hollyhocks can tolerate partial shade, they prefer a warm, full sun position. Too much shade will result in these tall plants flopping over, but excessively hot, dry weather can cause lower leaves to wither and die.

Soil

Part of the appeal of common hollyhocks is their ability to succeed in most soils. They prefer fertile, heavy soils, but, providing you enrich poor soils with organic matter, your plants should still do well.

Water

Common hollyhocks prefer evenly moist conditions, but wet winter soils are problematic. If your soil is not draining well during a wet winter, you could amend it with compost to improve air circulation and drainage. Water the roots and not the leaves of this plant, as wet leaves promote problems with the fungal diseases these plants are susceptible to.

Temperature and Humidity

Hardy down to about 5 degrees Fahrenheit, these plants are pretty cold tolerant. However, early frosts can damage the flowers. Ideal daytime temperatures for blooming common hollyhocks are around 65 to 70 degrees Fahrenheit.

Excessive humidity can result in problems with the fungal disease hollyhock rust.

Fertilizer

In terms of maintenance, one of the most important considerations for common hollyhocks is their nutrient levels. These plants love fertile conditions and are heavy feeders. Adding organic matter to your soil in the spring and applying an organic flower fertilizer or fish emulsion that is high in nitrogen every few weeks during the bloom period will result in bigger flowers and healthier foliage. Poor nutrient levels can result in yellowing of the plant's leaves and disappointing blooms.

Propagating Common Hollyhock

You can propagate common hollyhocks through division in the fall or spring when the plants are not flowering. Take root cuttings in winter (around December time, and you can propagate basal cuttings at any time of the year. Make sure to select rust-free plants.

How to Grow Common Hollyhock From Seed

Common hollyhocks are easy to grow from seeds. Sow seeds around late spring or late summer. The ideal temperature for germination is around 60 degrees Fahrenheit. Be patient: they typically take around two weeks to germinate.

Common Pests & Plant Diseases

The fungal disease rust can be a major problem for the foliage on the common hollyhock, and it can quickly spread and results in premature leaf drop and stunted growth. Removing the leaves on the lower part of the plant stem, cutting the plants back in the fall, and promptly removing the debris will help to minimize fungi problems and spread.

You might also find that Japanese beetles and spider mites are attracted to your common hollyhock, and young growth tends to be a tasty treat for slugs.

How to Get Common Hollyhocks to Bloom

The flowers of the common hollyhock are large (around 4 to 5 inches in diameter), face outwards on the long central stem, and come in various colors, including white, pink, red, yellow, and lavender. Some say the flowers resemble those of opium poppies (Papaver somniferum).

Although these plants are typically grown as biennials, meaning there will only be one flowering season, they have a long bloom period, lasting from mid-summer to early fall. A fertile soil with lots of nutrients, consistent moisture, and deadheading wilted blooms will encourage abundant, large, healthy blooms.

FAQ
  • Are common hollyhocks easy to grow?

    Although the common hollyhock grows from seed easily, they need the right amount of nutrients, spacing, and moisture levels to encourage healthy blooms and minimize problems with the fungal disease rust.

  • How long can common hollyhocks live?

    This species is a short-lived perennial that is typically grown as a biennial. This means you plant it one year and it blooms the next before dying off. With the right care and conditions, you may get a second year of flowering from your common hollyhock.

  • Where can I grow common hollyhock in my garden?

    These tall cottage garden favorites are well suited to be grown against walls or fences or as a stunning backdrop in beds and borders.