Alcea Rosea [al-KEE-uh, ROH-see-uh] the hollyhock plant is a genus of about 60 species of flowering plants in the Mallow (Malvaceae) family originating from southwestern China and exported to Europe in the 15th century.
When it became popular in Europe, William Turner, a renowned herbalist of the time, named the plant.
The Hollyhock plant fits the definition of old-fashioned garden plants.
They’re closely related to okra, cotton, and hibiscus.
The plant comes in a wide variety of colors: red, white, blue, pink, yellow, purple, and even black.
Common Hollyhock Plant Care
Size and Growth
Common Hollyhock grows tall with an average height of 6′ – 8′ feet tall.
It spreads around 1′ – 2′ feet, allow ample room for it to grow properly in your garden.
The hairy leaves of the Hollyhock are borne in clumps reaching 6″ – 8” inches across.
Blooms start at the base of the stem and continue to move upward 1′ – 2′ feet.
This ensures the entire stem is covered in bloom when the growing season starts.
Hollyhock flowers grow 2″ – 4″ inches in width.
Flowering and Fragrance
The Alcea rosea has a two-year life cycle, known as biennial plants.
Many of the available hollyhock varieties are biennials.
Depending on the soil and care, it will be annual or a short-lived perennial.
The first year is spent growing foliage and storing energy.
The second year or last year flowers bloom in late summer, seeds form, and flower stalks shoot up.
This species is a hermaphrodite (having both female and male organs).
It can have spires of single flowers and double flowers.
They have numerous stamens, and the stalks grow together.
The large, showy blooms attract hummingbirds, butterflies, and bees.
They have no particular scent.
Light and Temperature
Hollyhock plants need full sun and cannot grow in the shade.
A warm sunny location sheltered from the wind is ideal.
The plant is tolerant of the cold, but their flowers can become damaged by frost.
Seeds of the Hollyhock plant need to be sown from March-June in well-drained soil.
They should plant in large plug cells, and a pH level of 5.8-6.0 should be maintained.
For optimum germination, you need 55° – 60° degrees Fahrenheit (13° C – 16° C).
Germination can take place in up to 8 – 10 days.
After this occurs, you need a day temperature of about 65° – 70° degrees Fahrenheit (18° C – 21° C) while the night temperature should be 55° – 60° degrees Fahrenheit (13° C – 16° C).
Watering and Feeding
Alceas Roseas are heavy feeders and need high maintenance.
You will need to apply potassium nitrate and calcium at a rate of 75-100 ppm constant feed.
Don’t allow the soil to dry out since Hollyhocks need the ground to be evenly moist.
Soil and Transplanting
Hollyhocks are hardy to USDA Hardiness Zone 6.
They’re temperamental plants so transplanting is often discouraged.
They have large tap roots making them a challenge to dig up.
However, you may be able to do it successfully if you are careful enough.
Hollyhock seeds shouldn’t be moved until they have at least 4 leaves and the day temperature is more than 50° degrees Fahrenheit (10° C).
The soil where you plant Hollyhocks should be mixed with clay, sand, and plenty of compost.
Remove the seedling from its pot gently and crumble the soil from the root ball.
If it was growing in the ground, use a trowel to dig it out gently.
Plant Hollyhock seeds in a hole prepared with composted soil and slide the roots of the seedling into it.
Press the soil down with your hands but don’t cover the crown where the stem meets the roots.
If you do, the plant will rot.
Hollyhocks will readily self-seed new plants if not maintained.
While planting Hollyhock locate them where this won’t be a nuisance.
Growing Hollyhocks Grooming and Maintenance
The foliage of the plant needs to be kept trimmed and free from insects.
Remove any yellow leaves by hand.
High fertilizer levels also need to be maintained to prevent yellowing of lower leaves.
Do not use ammonium nitrate, it will produce cabbage-like leaves.
If proper maintenance isn’t conducted, the foliage becomes unkempt and tattered.
How to Propagate Alcea Rosea
Hollyhocks propagate by seed and by division.
Sow seeds outdoors about a week before the last frost.
For same year growth, sow throughout the growing season until 2 months before the first expected fall frost.
In non-blooming seasons, loosen the ground around full-grown plants and pull out the stalks.
Retain their long roots and place them in water.
Grow new plants in early spring, they need 4 months to mature, this is key to their summer colors.
If you missed this year’s spring it may be worth waiting until next spring.
Pests and Diseases of Hollyhocks
Anthracnose can damage the foliage, leaf spot, and rust.
Hollyhock rust is treated with proper ventilation and fungicide.
Prevent rust by watering from below, providing good air circulation and giving a thorough late fall cleanup.
Japanese beetles and spider mites feast on the leaves.
If unprotected from the wind, it needs staking.
Snails and slugs feed on seedlings.
Suggested Alcea Rosea Uses
Common Hollyhocks provide great architectural height which looks great against old cottage gardens.
They grow well against fences and walls.
In herbal medicine, the Alcea Rosea is used as a laxative and emollient.
It’s often used to control inflammation and bedwetting.
Some cultures use it as a mouthwash to prevent bleeding gums.
The young leaves can be eaten raw or cooked.
They have a mild flavor and textured leaves are desirable.
Chop them up and throw them in your salad.
The root has a nutritious starch which is good for your health.
The petals are often used to make a refreshing tea or extract oil.