Malva alcea, known as vervain mallow or hollyhock mallow, is a low-maintenance perennial flower that adds a splash of bright color to any garden. It is a clump-forming plant with palm-shaped leaves with five to seven lobes. Pink saucer-shaped flowers that look similar to hollyhock blooms appear in early summer through fall. Though short-lived (three to four years) hollyhock mallow does self-sow readily in the right conditions, so new volunteer plants crop up year after year.
Hollyhock mallow grows quickly, producing flowers in the first summer season after seeds are planted in the early spring or previous fall.
|Common Name||Hollyhock mallow, vervain mallow|
|Botanical Name||Malva alcea|
|Plant Type||Herbaceous, perennial|
|Mature Size||2-4 ft. tall, 12-18 in. wide|
|Sun Exposure||Full sun, partial shade|
|Soil Type||Moist but well-drained|
|Soil pH||6.1 to 7.8 (mildly acidic to mildly alkaline|
|Bloom Time||Summer to early fall|
|Hardiness Zones||4-7 (USDA)|
|Native Area||Europe, Asia|
Hollyhock Mallow Care
In the right conditions, hollyhock mallow is extremely easy to grow and maintain. It is a short-lived species that will fade after three or four years. However, the plant self-seeds readily producing new volunteers identical to the mother plant. The dense, bushy foliage is attractive and adds interest to the garden from early spring right through to the fall. For gardeners that love to attract pollinators to the garden, the hollyhock mallow is an ideal choice to attract bees and butterflies.
For many gardeners, virtually no maintenance will be needed. At most, you may need to stake up flowers to prevent toppling from strong winds or apply a fungicidal powder if disfiguring fungal leaf spots bother you.
In temperate regions, it's best to position your hollyhock mallow in a full sun position. If you live somewhere that experiences intense afternoon sun, a partial shade location would likely be better to prevent leaf discoloration and promote better flowering.
Hollyhock mallow can tolerate a wide variety of well-drained soil types. Its preference is moist loamy or sandy soil that is reasonably fertile. But if the soil is overly rich, it can result in the flower stems sagging.
This plant, once established, is moderately drought-tolerant. It prefers to be kept consistently moist but won't survive in waterlogged soils.
Temperature and Humidity
Hollyhock mallow enjoys temperate climates of zones 4 to 7 and can handle light frosts during the transition seasons. Excessively hot and dry conditions result in the foliage turning from green to a scorched yellow. High humidity climates often see problems with leaf fungal diseases.
Your hollyhock mallow will accept a monthly application of a balanced fertilizer during its flowering period, but it requires almost no feeding if the soil is moderately fertile. Avoid excessive feeding, as this can make the plant excessively leggy and cause it to sag.
Types of Hollyhock Mallow
By far the most popular variety of this plant is Malva alcea var. fastigiata sometimes known simply as "mallow" or "fastigiate hollyhock mallow." It is a narrower, neater plant than the pure species, with larger saucer-shaped pink flowers.
There are also other types of Malva species that are sometimes confused with M. alcea. For example:
- Malva sylvestris, including the popular "Zebrina' cultivar, is a very similar plant to M. alcea, but its soft pink flowers are marked with striking purple veins.
- Malva moschata (musk mallow) is very close to M. alcea, but it is suitable for colder climates. Be careful about cultivating this species, as it is regarded as invasive in some regions. It is a shorter-lived plant, often considered biennial.
Pruning of your hollyhock mallow is recommended to prevent this readily self-seeding plant from taking over your garden. For this reason, as soon as the blooms are spent, they should be deadheaded. This can sometimes also encourage a second flush of blooms in the late summer.
Cutting the entire plant back down to the basal foliage is also an option after the bloom period concludes in the late summer or fall. Be aware that some self-seeding might occur using this method. If you want to keep your hollyhock mallow neat and compact, it's worth pinching back new growth tips as they first appear in the spring. Be wary of adding hollyhock mallow clippings to a compost bin, as the seeds may persist and cause unwelcome volunteers when the mulch is used in the garden.
Propagating Hollyhock Mallow
New hollyhock mallow plants can be easily grown from healthy basal cuttings (cuttings taken from around the base of the plant) in the spring or early summer. However, this plant is so easy to grow from seeds that collecting seeds for replanting is a much more common method of propagation.
If you do want to try vegetative propagation, here's how to do it:
- In late spring or early summer, use a sharp, clean pruner to clip a section of root crown around the base of the plant just as it's beginning to put out new growth. It's best to clean the pruner between each cut to ensure you're not transmitting any fungal diseases. The cutting should contain both a section of the root crown as well as emerging green growth.
- Plant the basal cutting into a container filled with ordinary potting soil, and moisten it thoroughly. Applying a rooting hormone to the cutting before planting is optional.
- Continue growing the planted cutting outdoors in its pot until active new stem growth is evident—this usually takes several weeks.
- At this point, the new specimen can be transplanted into the garden.
How to Grow Hollyhock Mallow From Seed
Hollyhock mallows are extremely easy to grow from seeds purchased from online retailers specializing in wildflowers or collected from the dried seed pods on existing plants. There is usually no need to start seeds indoors. The normal outdoor planting time is spring as soon as the soil can be worked, but even seeds planted in fall will usually sprout in the spring. Plant the seeds shallow, barely covering them with soil. Germination and sprouting are usually evident within two weeks.
When cold weather kills the foliage, cut the stalks down to the basal leaves. (You can leave a few plants standing if you wish for them to self-seed in the garden.) In borderline climate zones, (northern range of zone 4), cover the plants with a layer of mulch or leaves for the winter to protect the roots. This mulch layer should be removed promptly in the spring to prevent root rot.
Common Pests & Plant Diseases
There are no life-threatening pests and diseases for this plant, though Japanese beetles will often feed on them in regions where this insect is prevalent. In hot, humid climates, the plants can be susceptible to several fungal leaf diseases. While unattractive, these diseases are rarely fatal; if necessary, they can be treated with fungicide powders or sprays.
How to Get Hollyhock Mallow to Bloom
Hollyhock mallow rarely needs help to bloom, but deadheading spent flowers will encourage additional blooms. A plant that fails to flower at all is probably not getting enough sunlight.
Common Problems With Hollyhock Mallow
Hollyhock mallow is typically easy to grow, and the problems that do occur are cosmetic rather than life-threatening. Some common issues include:
Their ability to readily self-seed can prove to be an annoyance for some gardeners as volunteer seedlings can be tricky to remove once they are established. Careful deadheading and cutting back will be required during the summer if you want to prevent spreading.
With its tall, upright form, this plant may require staking in exposed windy locations or if growing in rich soils that cause legginess. Selecting a sheltered position out of strong winds is recommended.
How is hollyhock mallow used in garden designs?
This upright species is ideal for use as a border plant and looks good in informal wildflower meadow or cottage garden settings. They deliver large, vibrant, and showy pinkish-purple, five-petaled flowers in the summer and fall.
Is hollyhock mallow invasive?
Several species of mallow (such as musk mallow, Malva moschata) are considered invasive due to the ready way they self-seed, but Malva alcea is generally not regarded as such a problem plant. That said, keep watch on plants growing in border areas to make sure they don't spread. Regular deadheading of spent flowers will keep it under control.
How long do hollyhock mallows live?
Lifespan is a deceptive issue with hollyhock mallows since self-seeding creates volunteer plants that can sustain a garden patch. But individual plants rarely live more than three or four years.
Where can I get hollyhock mallow plants?
Live plants or seeds for this plant are not commonly sold at garden centers by major seed manufacturers. Your best bet will be to buy seeds from online retailers specializing in wildflowers. Be careful to ensure you are getting this species rather than another type of Malva.