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The ultimate guide to hollyhocks: Growing, care, and more

Updated: Sep 24, 2023

Hollyhocks are an iconic garden flower that’s seen everywhere from coastal gardens to cottages across Europe. They’re easy to grow and come in a rainbow of colors, making them a popular choice for gardeners of all levels.


In this article, we'll explore some of the most frequently asked questions about hollyhocks, including when they bloom, how to grow them, and what to do with them after flowering.


We'll also look at the best hollyhocks to grow, the most common colors available, and answer questions like whether they are poisonous to dogs or if they spread. So when you’re ready to add height, color and texture to your garden, read on to learn all about hollyhocks!



What are hollyhocks?


Hollyhocks (Alcea rosea) are tall, towering flowers that are native to Asia and have been grown in cottage-style gardens for hundreds of years. In Denmark, they’re called ‘stockrose’ which translates to ‘cane rose’ — because they look like beautiful roses stuck on a long, tall cane.


This gorgeous short-lived perennial is part of the Malvaceae family and is loved for its large spikes of brightly colored flowers that bloom in the late spring or early summer.


Hollyhocks can reach up to 6 feet tall (2 meters) and can spread up to 2 feet wide (60 cm), making them the perfect choice for the back of a border or as a focal point in your garden.


They’re very easy to care for and can return year after year if they’re allowed to self-seed. Most varieties will only live for 2-3 years, but if you let them seed, you’ll have plenty of hollyhocks every summer.



How to grow hollyhocks


Hollyhocks are sun-loving plants. They need full sun and organic-rich, well-draining soil. Ideally, soil pH should be between pH 6.0 - 8.0, from slightly acid to alkaline.


One of the biggest mistakes I see with hollyhocks is when people plant them in shady corners of their yards and gardens. There are other shade perennials for those areas — give your hollyhocks all of the sunshine they want.


They’re also drought-tolerant and can handle some neglect, making them a great choice for busy gardeners.


To help your hollyhocks thrive, water them regularly and add compost or other organic matter to the soil each year. Hollyhocks are susceptible to powdery mildew (a type of fungal disease). To be safe, give them plenty of space for good air circulation and avoid overcrowding.


Common Name: Hollyhock

Botanical Name: Alcea rosea

Family: Malvaceae

Plant Type: Perennial

Mature Size: 3-10' tall and 1-2' wide

Sun Exposure: Full sun to part shade

Soil Type: Rich, well-draining soil

Soil pH: Neutral to slightly alkaline

Bloom Time: Summer Flower

Color: Pink, red, yellow, white, and purple

Hardiness Zones: US 4-9

Native Area: Asia, including China and Iran


facts about hollyhocks

When should you plant hollyhocks?


Hollyhocks do best when they’re planted in the spring.


This is because they need warm soil and long days of summer to germinate and grow. If you live in a mild climate, you can plant them in the fall, but keep in mind that they may not bloom until the following year.


When planting hollyhocks, remember to give them enough space to spread out. These plants will become quite large, so if you’re planting more than one hollyhock, space them at least 2 feet apart (60 cm) to allow for good air circulation and to prevent the spread of disease.



When do hollyhocks bloom?


Hollyhocks (Alcea rosea) usually bloom in the late spring or early summer, giving you incredible spikes of flowers that will tower above your garden or border.


Not only are the flowers gorgeous and give you the cottage-style garden look that you’re after, but they also attract a variety of pollinators like bees, butterflies, and hummingbirds to your garden.


Once the blooms begin to fade, the plant will set seed, and it will continue to self-seed in your garden for years to come.


You can deadhead hollyhocks, too. Just pinch or clip off any blooms that have faded before the seed pod forms. It's a great idea to do this throughout the growing season to promote more growth and flowers. If you want them to self-seed, just leave the last blooms at the end of the season so they can go to seed.



How many colors do hollyhocks come in?


Depending on the variety you grow, you can enjoy flowers in a wide range of colors, including shades of pink, red, yellow, orange, white, and purple.


Some varieties have bi-colored flowers or flowers that change color as they mature. You can also find hollyhock varieties with speckled, striped, or ruffled flowers.


With so many colors and flower forms to choose from, there’s a hollyhock for every taste and garden style. Let me know your favorite color in the comments below.



How long do hollyhocks take to flower?


Hollyhocks are different from most perennials in that they typically take 1 to 2 years to flower, depending on the variety and the growing conditions.


If grown from seed, hollyhocks will bloom in its second year of growth.


If you start hollyhocks from plants or cuttings, they may flower sooner, sometimes within the first year.


Once they begin to flower, hollyhocks will continue to bloom for several weeks, producing spikes of brightly colored flowers that will absolutely steal the show in your garden or border.



How to grow hollyhocks from seed


Hollyhock seeds can be started indoors about 6 weeks before the last expected frost date. Or you can sow them directly in the ground outside in the spring, about a week before the last frost.


When starting hollyhocks seeds indoors, make sure you provide plenty of light and keep the soil moist but not wet.


When starting seeds directly in the garden, simply scatter the seeds on the surface of the soil, cover them with a light layer of soil, and water regularly. They don’t need to be buried — around ¼ inch (6 cm) deep is fine. I’ve found that just covering them with a layer of soil is the easiest method.


Remember to plant seeds, seedlings or plants at least 2 feet (60 cm) apart because they love to spread.



Where is the best place to plant hollyhocks?


Hollyhocks need full sun and well-drained soil that is rich in organic matter. Any area of your garden or border that meets those requirements is the perfect place to plant.


Hollyhocks can also handle some drought and even partial shade. So they can be planted in areas where water is limited. They’re also tolerant of wind, making them a good choice for coastal gardens.


When planting hollyhocks, be sure to give them enough space to spread out, as they can become quite large, and allow for good air circulation, which will help to prevent the spread of disease.


If you’re planting them in a border, I recommend that they go in the back. Just because of the height. You’ll get to enjoy the flowers without worrying about them hiding other perennials planted behind them.


When we lived in our old Danish farmhouse (over 400 years old!), we had them planted outside our front door. They do become quite tall, so we had to tie them back against the door frame near the end of the season.


Even now, we plant them next to our fence and tie them back when they get tall. This is just to keep them from drooping or falling over as the blooms get heavier and heavier.



What are the best hollyhocks?


This is like asking what’s the best Danish pastry. They’re all delicious. And all hollyhocks are gorgeous.


The ‘best’ hollyhock is the one that you love to look at. Some popular hollyhock varieties include: "Chater's Double," "The Watchman," and "Nigra." These varieties are known for large, brightly colored flowers, strong stems, and disease resistance.


When choosing hollyhocks, think about flower color, growth habits, and disease resistance, as well as your local climate conditions. And then choose your favorites. In my experience, you can’t really go wrong — they’re all gorgeous.



What are the most common hollyhocks?


The most common hollyhocks are single-flowered varieties with solid-colored flowers.


You’ll most often see colors like pink, red, or white. These types of hollyhocks are widely available and very easy to grow, making them a great choice for beginner gardeners everywhere.



Do hollyhocks multiply every year?


Hollyhocks are biennial plants, meaning they usually bloom in their second year of growth.


However, if you allow them to self-seed, hollyhocks will come back year after year. Here’s what I mean… as the flowers fade, they produce seeds that fall to the soil. If the seeds are not removed, they’ll germinate and grow into new plants, meaning that you’ll always have hollyhocks in your garden.


If you prefer to keep your hollyhocks in one location and not have them spread, be sure to remove the seeds before they have a chance to fall or be eaten by birds and distributed or blown around your garden by the wind.



Should hollyhocks be cut back for winter?


Hollyhocks can handle cold weather and are hardy in USDA zones 3-9 and most of Europe (including Denmark’s cold climate and that in the UK). They can survive temperatures as low as -40°F (-40°C).


To help them survive winter, it is a good idea to cut back the plant stalks and leaves to about 6 inches (15 cm) from the ground after the first hard frost.


This prevents the buildup of old plant material, which can harbor diseases and pests. If you live in an area with severe winters, I recommend adding a layer of mulch, leaves or straw around the base of the plants to help insulate the roots.



Will hollyhocks spread?


As I’ve mentioned before, hollyhocks can spread through self-seeding, meaning they will produce seeds that can germinate and grow into new plants.


This is great if you want your hollyhocks to come back year after year. But if you prefer to keep them in one spot, be sure you remove the seeds before they have a chance to fall and spread.


Hollyhocks can also spread through their roots. Be sure you plant yours at least 2 feet (60 cm) apart to give them enough space to spread out.



Do you cut down hollyhocks at the end of the season?


I suggest cutting down your hollyhocks after the first hard frost to help them survive the winter and prevent any disease and pests from setting in.

  • Cut back the plant stalks and leaves to about six inches (15 cm) from the ground and add a layer of mulch around the base.

  • If winters are extremely cold in your area, you may want to provide extra protection such as covering the plants with a layer of pine boughs.



Can you dig up and replant hollyhocks?


Yes, you can dig up and replant hollyhocks.


Hollyhocks have a deep root system, so be sure you dig deep enough to get as much of the root system as possible. Then, transplant them to a new location, making sure to give them enough space to grow and spread out.


Water the plants well after planting and mulch around the base of the plants to help retain moisture and prevent weed growth.


With proper care, hollyhocks should establish themselves in their new location and produce the beautiful flowers you’re hoping for year after year.



Can you just scatter hollyhock seeds?


Yes, you can scatter hollyhock seeds directly in the garden and get more plants next spring.


You’re basically mimicking what the plant is doing itself when it self-seeds. To scatter hollyhock seeds, simply scatter the seeds in a well-prepared area in a sunny location, cover them with a light layer of soil, and water well.


Hollyhocks prefer well-draining soil and a sunny location, so be sure to choose a spot that meets these requirements. Keep the soil consistently moist until the seeds germinate, which usually takes 7-14 days.



How long do hollyhocks live?


Hollyhocks are biennial plants, meaning they will grow leaves and stems in the first year and then produce flowers in the second year.


After they’ve flowered and set seed, the plants will die.


However, hollyhocks can self-seed and come back year after year. If you want to keep your hollyhocks coming back, be sure to leave some of the seed heads on the plant at the end of the season so the seeds can fall to the ground and germinate.



What to do with hollyhocks after flowering?


After hollyhocks have flowered and set seed, the plants will die.


To prevent the buildup of old plant material and to protect your plant during the cold winter, cut the plant stalks and leaves down to about six inches (15 cm) from the ground.


Remember that If you want to keep your hollyhocks coming back every year, leave some of the seed heads on the plant at the end of the season so the seeds can fall to the ground and germinate. If you don’t want hollyhocks to come back, remove the entire plant, including the roots.



Do birds eat hollyhock seeds?


Yes, birds often eat hollyhock seeds.


Hollyhocks are a major food source for many different species of birds, including finches, sparrows, and goldfinches.


If you want to encourage birds to visit your garden, consider planting hollyhocks in a location where they will be easily visible and accessible. And don’t worry about them eating all of your seeds, your hollyhocks will still have plenty to self-sow for the next year.



Are hollyhocks poisonous to dogs?


No, hollyhocks are not lethal or toxic to dogs.


However, like all plants, hollyhocks can cause digestive upset in dogs if they consume a large amount of the plant.


If you have a dog that is prone to eating plants, it may be best to plant hollyhocks in a location where your dog can’t reach them. These plants are really tall, so the back of your border will work great and keep your curious pooch from snacking on the leaves and flowers.



How do you keep hollyhocks healthy?


To keep hollyhocks healthy, provide them with the right growing conditions. Sounds simple enough, right? It is!


Hollyhocks prefer well-draining soil and a sunny location.


They also benefit from regular watering, especially during periods of drought. To keep them safe during extreme winters, cut the plant stalks and leaves down to about six inches (15 cm) from the ground at the end of the season.


And my number one tip is to add a layer of organic mulch to the soil around your hollyhocks. This will encourage healthy growth and promote abundant flowering. Who doesn’t want that?



Are hollyhocks and Rose of Sharon the same?


No, hollyhocks and Rose of Sharon (also known as hibiscus syriacus) are not the same plant.


Although they are both members of the Malvaceae family, they are distinct species with different growing habits, flower forms, and growing requirements.


Hollyhocks are tall, biennial, or short-lived perennials with large, showy flowers, while Rose of Sharon is a shrubby perennial with smaller flowers.


Got any more questions about hollyhocks? Just drop them in the comments below and I’ll update this article with the new information.