Hollyhocks produce beautiful flowers in a variety of colors but are short-lived. Thankfully, they’re very easy to grow and propagate so that you can continue your population of hollyhocks without much effort.
However, they are susceptible to harmful insects and diseases like powdery mildew, and rust. And there are other important care tips, which we are going to cover in this article.
Hollyhock Quick Facts
|Scientific Name:||Alcea rosea|
|Type||Short-lived perennials and biennials|
|Watering||Maintain moist soil|
|Light||Full sun to partial shade|
|Height||Up to 9 feet|
|Humidity||Low to average|
|Toxic||Stems and leaves can cause skin irritation|
|Pests||Spider mites and thrips|
Alcea rosea ‘Chaters double’
These hollyhocks have a romantic feel, with their frilly double flowers. They bloom in their second year and come in a variety of colors.
Alcea rosea ‘Blacknight’
This hollyhock makes a real statement in any garden, with its unusual flowers in a deep shade of almost black. It is the darkest flowering hollyhock available and acts more like a perennial than biennial.
Alcea rosea ‘Majorette mix’
If planted soon enough, this dwarf hollyhock will bloom in the first year. It comes in an array of colors, including orange, red, yellow, and pink. It grows to just two feet tall and has a bush-forming habit.
Alcea rosea ‘Fiesta time’
In a vibrant cerise pink, this hollyhock blooms in its first year of life. It grows to three feet tall, making it ideal for growing in containers.
Hollyhock Care Guide
As young plants, hollyhocks must have continuously moist soil. In order to avoid root rot or waterlogged soil while still allowing the plant to get the level of water it requires, ensure your hollyhocks are planted in well-draining soil. Always water the plant at base level and try to avoid spraying the leaves or using sprinklers, as damp foliage is more prone to disease.
It’s a good idea to water this plant in the morning so that any wet leaves will dry off in the sun to prevent disease taking hold. As the plant reaches maturity, it will become drought tolerant and will not need to be watered as frequently. Hollyhocks grown in containers will require more water than those planted in the ground as the soil dries out more quickly in containers, and the roots aren’t able to seek out moisture further along in the soil as they can in the ground.
The amount of light your hollyhock needs will dictate where you plant it. Hollyhocks like plenty of sun, but they can also get scorched or wilt in extreme heat, so the amount of sun you can allow your hollyhock to receive will depend on your local climate. If your summers are fairly cool, then a position of full sun will be fine for your hollyhock, whereas if you live in a climate where summers are scorching hot, you will need to position your hollyhock in a spot where it can be protected from the afternoon sun.
Hollyhocks need at least six hours of direct sun a day in order to bloom, so pay careful attention to ensure your plant will get the necessary quota of sun if you are planting it in a position of partial shade.
Hollyhocks grow in a temperature range of 60-90º F as long as conditions are ideal. If the temperature drops below 55º F, it will die back to the ground, and you will need to mulch the soil in order to insulate the dormant roots to protect them from getting too cold.
When the temperature reaches the top end of the scale and gets much warmer than 85º F, you will need to pay extra attention to watering your hollyhock, as the soil will dry out more quickly in this heat, and maintaining moist soil is vital for hollyhocks in hot climates. In very hot climates, you should ensure the plant is shaded during intense afternoon heat so that the plant doesn’t overheat. Also, take care to protect the plant from wind by positioning it in a sheltered location.
Hollyhocks don’t have any humidity requirements and actually fare worse in climates with high humidity as this makes them more susceptible to diseases such as rust. Hollyhocks need good air circulation, so enable this by planting them around 18 inches apart.
Most hollyhocks are biennials, which means they produce vegetation in their first year, and flower in their second year, before completing their life cycles. In some conditions, hollyhocks will flower for several years, where they are considered short-lived perennials. If you enjoy having hollyhocks reappear year after year, you needn’t be concerned by their short life span, as they are able to reseed without any intervention.
To allow the hollyhocks to reseed and produce future years of plants, simply refrain from deadheading the flowers until the seeds have dropped and dispersed. If you’d like more control over where the seeds get planted, you can harvest the seeds from the spent hollyhock flowers and sow them yourself. They can be sown indoors over winter ready for transplanting outside in spring, or you can sow them directly into the ground in spring.
Hollyhocks require very little pruning, though you can cut back the stalks after the flowers are spent. Flowers can be deadheaded at the end of their lifecycle, unless you want the plant to reseed, in which case, leave the flowers until seeds have dispersed. In fall, the plant will die back to the ground. At this point, you should cut the stalks back to just a few inches in height and apply straw or mulch over the top of the cut stalks to help the dormant roots survive winter. In spring, slowly remove layers of mulch to help the plant acclimate.
Hollyhock flowers are the attraction of this plant. They come in various colors, including pink, purple, red, blue, white, and yellow, and cover their spike-like stems from base to tip. They bloom in the plant’s second year, appearing in mid-summer and typically lasting from June through to August. The flowers are quite large, measuring around four inches across, and are shaped like shallow funnels (Royal Horticultural Society).
Common Pests and Diseases
Hollyhocks are susceptible to a host of pests and diseases, including rust, powdery mildew, anthracnose, spider mites, and thrips.
Hollyhock rust is a fungal disease that thrives in hot, humid, moist areas. It will begin on lower leaves of the plant, which are closer to soil level and are subject to more moisture. Early stages of rust appear on the underside of leaves as orange-brown flecks and develop into pustules. As the disease progresses, the top side of the leaves will display yellow spots.
It’s important to remove a plant suffering from rust as soon as it is identified, as the disease is fatal for plants and can spread quickly. Help to defend your hollyhocks against fungal diseases by treating them with a preventative fungicide, leaving adequate space between plants, and watering at soil level.
This is another fungal disease that is characterized by a white powdery substance coating new growth on the plant. It occurs in areas which have high humidity teamed with dry soil – for example. in hot and humid climates with very little rainfall. Powdery mildew will spread quickly and kill the hollyhock, so it is important to remove the plant and dispose of it as soon as the disease is identified.
Prevent powdery mildew by ensuring good airflow around the plant, maintaining moist, well-draining soil, and staking plants upright so that infected plants cannot bend over and spread the disease to neighboring plants.
Which variety of hollyhock do you like best? What has your experience been like growing them? Let us know with a comment, and don’t forget to share this page with other flower enthusiasts!