Hollyhocks are a staple of the cottage garden and mixed flower bed planting schemes. Usually a biennial plant hollyhocks produce flowers on tall spikes at the height of mid summer, from June until August. While many varieties are biennial, flowering in their second year, some cultivars are similar to perennials. This means that they flower in their first year if planted early enough.
Apart from regular pruning and staking hollyhocks, for all their ornamental value, are pleasingly easy to care for.
Stately and elegant, hollyhocks are a great way to add color and structure to your garden. They are also pleasingly easy to care for.
Warning while hollyhocks aren’t toxic the stem and foliage can irritate the skin. Wear gloves and a long sleeved top when planting or pruning your hollyhocks.
- General Information About Hollyhocks
- Different Hollyhocks Varieties
- Where to Plant Hollyhocks
- How to Plant
- Caring for Hollyhocks
- Important Points About Harvesting Seeds from Your Hollyhocks
- Common Pests and Problems
General Information About Hollyhocks
Hollyhocks first originated in Asia around the Eastern Mediterranean Sea region. They are stately beauties that belong to a family that has over an impressive 1,500 different species. Out of these 1,500 species, 27 of them are only found in North America. Each member of the Mallow (Malvaceae) family has a very distinct look to them, so if you’re someone who thinks that hollyhock looks like a Hibiscus, you’re not alone.
If you do a quick Google search to see where this flower is hardy to, you’ll get a decent amount of sources that they’re usually hardy from USDA zone 3 to 8. When we say that they’re generally hardy, we mean that they’ll typically do well in these zones. However, you have to know that Zone 3 encompasses areas in the far northern portions of the United States. In this area, the winters are pretty extreme, and it’s difficult to predict how cold the different regions will get during this season.
This being said, we advise anyone who wants to plant hollyhocks in these areas with more extreme winters to plant them in a location where they’ll have protection from severe cold. It’s also a good idea to cover the ground with a several inch thick layer of mulch. The alternative you have is to plant them in containers and overwinter them inside or in a sheltered area like a garage. In fact, if you live in an area where permafrost is normal, this is the ideal situation. This means that your area has long winters where the ground is frozen for months.
On the opposite end of the spectrum, people who live in zone eight have a whole new issue. This zone gets long stretches during the summer where the temperature hovers right around 100°F. Also, in certain places like in central Texas, spring comes and goes very quickly and the scorching summer temperatures set in and hang around until October. If your daytime temperatures rarely drop below 90°F, it’s not good for growing a host of flowers, including hollyhocks.
It’s also important to understand that simply reading the seed package and deciding to grow this plant because the hardiness zones are between 2 and 8 doesn’t mean that you’ll be successful with them. You have to be prepared to protect your hollyhocks from any extreme weather from polar vortexes to hurricanes.
Different Hollyhocks Varieties
Hollyhocks are hardy in USDA zones 3 to 8.
Coming in shades of blue, purple, pink, red, yellow, white and black, hollyhocks can be single, double or cup shaped flowers. While many flower on long stalks, others produce only short stalks or no stalks at all.
Most varieties reach 6 to 8 ft in height and have a spread of up to 2 ft.
Alcea Rosea is the most common variety of hollyhock. Growing in USDA zones 4 to 10 it reaches up to 8 ft in height. A self-seeding variety alcea rosea comes in a range of colors, attracting hummingbirds and butterflies to the garden.
The alcea rosea cultivar Icicle produces striking, double white flowers. Another alcea rosea cultivar, Penaches-N-Dreams, produces attractive double, petal peach colored flowers. The cultivar Scarlet Eye is noted for its rich red double flowers.
Hollyhocks come in a range of heights and colors. While some varieties have a relatively short flowering season, others can flower throughout the summer.
Alcea Ficifolia, or the fig leafed hollyhock, is not as widely known as Alcea Rosea but is just as attractive. Producing large white and cream flowers in abundance throughout the summer, these are pleasingly robust plants. One of the most popular Alcea Ficifolia cultivars is Happy Lights.
The deep purple or black flowers of Alcea Nigra sit in stark contrast to other, brightly colored varieties. This cultivar is a great way to add contrast, or just something unusual to your garden. Alcea Nigra cultivars include the attractive Arabian Nights plant which produces deep purple flowers.
Alcea Rugosa is known for its soft yellow flowers. Easy to grow in full sun positions, this variety originates in Russia. When planted in larger beds, clusters of Alcea Rugosa are particularly pleasing to the eye.
Where to Plant Hollyhocks
Hollyhocks are a great way to not only add height to a border but can be planted with other tall plants to create a natural screen bringing privacy to an area.
Hollyhocks do best in full sun positions. They also grow in partial shade. However growth may be slower and flowering not as abundant.
Your chosen position should not be windy, or it should have some shelter from strong winds. A tall, stately plant, hollyhocks are prone to wind damage.
Plant in rich, well draining soil. You can improve poor soil by working in well-rotted manure or aged compost before planting.
These are bright, sun loving plants. If you get the positioning of your hollyhocks right, they will be pleasingly easy to care for.
How to Plant
Hollyhocks can be purchased as young plants and planted straight into the garden. They can also be started from seed. This is often cheaper and allows you access to a wider variety of plants. The downside of growing from seed is that it takes longer and requires more effort on your part.
Starting Hollyhocks from Seed
Sow seeds directly outdoors into a well worked bed about a week before the last frost date. Sow thinly, about 2ft apart, to a depth of around a quarter of an inch. The soil should be moist when you sow.
Don’t allow the soil to dry out until the plants are established. Regularly weed the beds. Fast growing weeds can smother young plants. There are a number of useful tools to help you keep your garden weed free.
You can also start the seeds indoors. This is particularly useful in cooler climates where the last frost date is relatively late in the year. Begin sowing seeds indoors around 9 weeks before the last predicted frost date.
Fill tall containers with fresh potting soil. Hollyhocks are known for their production of long taproots. Sowing in tall pots allows the root to develop without becoming stunted or deformed.
Sow one seed per container. Water well and allow to germinate. Germination usually occurs within 14 days. In cooler conditions germination may take longer.
How to Plant
Begin hardening off in preparation for planting 2 to 3 weeks before the last frost date.
Before planting, dig the soil over and work in compost. Working in compost helps to enrich the soil. It also helps to improve drainage.
Dig a hole large enough to hold the plant. If you are unsure how large the hole should be, place the container currently holding the plant in the hole. The container should comfortably fit in the hole.
When you are ready to plant, carefully remove the hollyhock from the container. Take care not to damage the taproot. If the plant is difficult to remove, gently squeeze the sides of the container. This loosens the soil, allowing you to slide the plant out of the container.
Position the plant in the center of the hole. The top of the tap root should sit just below the soil level. Carefully fill in the hole, being careful not to compact the soil. Water well.
Planting in Containers
Your container should be large and deep. Ideally the container should be 12 to 16 inches deep and about 24 inches wide. Repurposing an old barrel allows the tap root lots of room to grow. Dwarf varieties have smaller roots so can be planted in shallower containers.
Your chosen pot should be clean and have drainage holes in the bottom.
Fill the container will light, well draining potting soil. A mixture that is equal parts garden loam, peat moss and perlite is ideal. This combination drains well while retaining some moisture. It is also light enough to allow air to circulate around the roots.
Place some pebbles or crock in the bottom to improve drainage. Fill the container with your chosen potting medium and plant as you would in the ground.
Caring for Hollyhocks
Once germinated hollyhocks are pleasingly easy to grow. If you are cultivating taller varieties remember to provide a bamboo stake, trellis or some other form of support.
Supports are best installed when you plant. This allows you to get young plants off to a good start, encouraging an orderly growth habit from the start.
Plant away from windy positions. Taller plants are prone to bending and snapping. Planting in front of a fence or wall not only helps to protect plants from the wind. It also provides some natural support for the plants as they grow.
When to Water
Water young plants well. Aim to keep the soil evenly moist.
Established plants are pleasingly drought tolerant and can go for longer periods between waterings. If you find a watering can, when full, too heavy to carry expandable hoses are a great way to water large areas with ease. As well as being easy to use they are also pleasingly durable.
When watering, try to water only the base of the plant and the surrounding soil. Keep the foliage as dry as possible. Wet leaves can create a humid environment. This, in turn, can become a breeding ground for disease.
Should I Apply a Fertilizer?
If planted in rich soil there is no need to fertilize.
Growing plants will benefit from a light application of general purpose fertilizer. This is best applied in the spring, just as new growth begins to emerge.
Alternatively, once a year, work compost into the beds around the plants. Like applying a fertilizer, this is best done in the spring just as new growth emerges.
How to Prune
Many varieties of hollyhocks freely self seed. To prevent this, use a garden scissors to cut away the flowers and stalks as they fade.
If you want the plants to self seed allow a few spent blooms to go to seed.
Cut back spent flowers and foliage in the late fall, after the seeds have dropped. Pruning in the fall helps to prevent overwintering rust diseases from striking.
How to Over Winter Hollyhocks
In colder areas hollyhocks are commonly grown as an annual. Allow spent flowers to go to seed and harvest. Sow the seeds, as described above, in late winter. Following germination the young plants can be planted out in early spring.
In warmer climates hollyhocks can be overwintered.
To overwinter, prune away spent growth. Aim to cut the plants down to about 6 inches above the ground. Cover with a layer of straw or mulch, about 5 inches thick. Alternatively a horticultural fleece, such as the Gardaner Plant Cover, can be used. This will protect the plant from harsh frosts while still allowing moisture to penetrate the soil.
In the spring, as temperatures warm, gradually remove the mulch. Slowly exposing the plant and root system to cooler temperatures gives them time to acclimatize. It also helps to prevent shock. If a spring freeze threatens, reapply the mulch.
Regularly check the plant for signs of new growth. When the green shoots begin to emerge, completely remove the mulch.
How to Propagate
The easiest way to propagate hollyhocks is from seed. A self-seeding plant, hollyhocks happily reproduce, and spread, if spent flowers are allowed to go to seed.
If you want to control the spread of the plants deadhead some of the spent flowers. Allow the remaining spent flowers to go to seed. This means that the flowers shrivel up and turn brown. As the petals fall from the plant, fuzzy seed pods emerge.
Important Points About Harvesting Seeds from Your Hollyhocks
These plants flower from the bottom up, and you can encourage flower production by removing flowers that wilt once they bloom. If you wait to harvest the seeds with the intention of planting them to get the same hollyhock variety, you should stick to a single cultivar. Hollyhocks also produce their seeds using cross-pollination, and you have a risk of harvesting the seeds from a crossbred hollyhock if you plant different types.
If you plant your hollyhocks in an area where you can’t see the bottom of the stalks, you might want to leave your spent flowers on the bottom so that the seeds end up developing there to make them easier to harvest.
Hollyhocks will develop seed pods that slowly expand as the seeds ripen as mature, just like any flowering plant that produces seeds. Once your seeds are mature enough for you to harvest, the pod turns a brown color because it will dry out. The seed pod will pull away from the stem of the plant very quickly, so you can use this to gauge whether or not the seeds are ready to harvest.
- Never collect seeds for a diseased hollyhock, especially if said disease is one that will stay dormant over the winter months. From our standpoint, as much as we love to harvest and hoard seeds from all of our plants, we don’t take chances when it comes to potentially spreading diseases in the spring when they start to develop.
If you’re trying to harvest seeds that are copies of the parent plant, don’t plant different species or cultivars at the same time. Unless you’re someone who has a large property where you can plant them at least ¼ of a mile apart, you’ll get cross-pollination where you end up harvesting crossbred seeds. If you want to collect seeds and ensure said seeds have the DNA of specific cultivars, variety, or species in your garden, stick to that type for one growing season.
Common Pests and Problems
Hollyhocks are prone to rust. This is a fungal infection which first presents itself in the form of yellow spots on the foliage of the plant. This develops into brown bumps appearing on the underside of the leaf.
Affected leaves should be cut from the plant and destroyed. Fungicides such as the Spectracide Fungicide spray which contain sulfur or copper can also be used to treat rust.
Some varieties such as Alcea Rugosa are rust resistant. Adopting good growing practices helps to keep plants problem free, it is also far easier than trying to cure the problem. To prevent rust water the plants from below and ensure they are correctly spaced so that the air can circulate freely. Pruning every fall also helps to keep plants healthy.
How Hollyhock Rust Spreads
Fungal spores will spread easily and quickly through splashing rain and wind. It can easily spread through splashing water, and this is a certain thing when you don’t water the plants with an underground irrigation system or a soaker hose. The disease will progress as the summer progresses, and it’ll travel up your plant stalks. Eventually, this will cause thick stems that turn a brown shade before they wilt, dry up and fall away from the plant.
Plant parts that are infected with this disease can spread it to nearby plants and to weeds. This is why you want to have enough space between your hollyhocks when you plant them. It’s also important that you keep your flower bed free of weeds. If the disease spreads to one plant, it’s extremely likely that you’ll have more plants get infected. They may not even show symptoms right away. These spores can also survive over the winter months, so you want to avoid harvesting seeds from any diseased plants.
The most effective way that you can manage this disease is by combining fungicidal treatments with proper watering practices. Look for a fungicide that has sulfur as the main fungicide. They’re safe for wildlife, environmentally-friendly, and safe to use around pets and children.
A fungi causes anthracnose, and it belongs to the genus Colletotrichum. The genus falls into a group of common plant diseases that are responsible for a range of diseases that can infect a range of plant species. It is characterized by dark lesions that are water-soaked appearing on all parts of your hollyhock plant. It’s a very quick-spreading disease, and the lesion’s surfaces will develop a bright pink spore mass that has a nasty gelatinous consistency. It can easily take a beautiful plant into a pile of wilted and rotted debris within a few short days.
It will survive through the winter months because the spores can easily hide in garden debris, the soil, and in seeds. It does best in very moist conditions, and these conditions allow it to germinate. The moisture and cool weather combination allows the fungus to spread and develop, and it can spread using wind, contaminated garden tools, insects, and rain.
Treating and Preventing an Anthracnose Infection
- Apply your treatment early in the morning
- Avoid working when your garden is wet
- Clean up areas where your infected plants were. Don’t leave any diseased plants in the ground.
- Don’t apply sulfur or copper treatments during hot weather
- Look for seeds that originate in the western part of the United States because this disease is more common in the eastern portion
- Never save any seeds that came from infected plants
- Never put any part of this diseased plant into a compost pile
- Prevent the disease before it takes hold by developing a weekly routine of spraying your plant with a liquid copper and using sulfur powder
- Start your treatment routine early in the spring as soon as your plants start to sprout
- Treat bare roots and seeds with fungicides as a precaution
- Use one part bleach to four parts water to disinfect and clean your garden tools
Protect plants from slugs, snails and Japanese beetles.
Controlling Japanese Beetles and Preventing Damage
- Create an area in your yard to attract insect-eating birds. By taking steps to attract these birds to the area and giving them a huge feast of bugs, you can allow the birds to naturally take your beetle population down.
- Get a bucket and fill it with soapy water. Walk though your yard or garden to look at every shrub, flower, or tree to see if you can spot these beetles. Pick the grubs or bugs off one by one and put them into your bucket of soapy water. As nasty as this sounds, it’s a lot better than using potentially toxic and expensive pesticides.
- These beetles prey on grass and flowering plants. It’s impossible to prevent a large infestation unless you work with every potential target plant. Sprinkle a decent amount of Diatomaceous Earth on any susceptible plants and grass.
Spider mites, another common pest, can be difficult to remove. Leaving a mat of webbing over plants, large infestations are best pruned away. Smaller infestations can be treated by washing away the pests or by wiping the foliage with neem oil.
With a little care, hollyhocks can add color and structure to a floral summer garden. Despite their elegant appearance these are pleasingly robust plants that are also popular with pollinators.
Capable of reaching up to 10 ft in height, hollyhocks are a stately addition to the back of a flower bed. The blooms look particularly attractive when planted alongside other ornamental plants such as dianthus, phlox, roses, clematis, dahlia and larkspur. In addition to adding drama and color to the garden hollyhocks also attract hummingbirds and butterflies to the garden.