How to grow hollyhocks

Choosing a hollyhock

Hollyhocks are fully hardy and flower in the second year after sowing. They are short-lived perennials and available in both single and double flowers. Before choosing which to go for, you might like consider the following:

• Have you got a suitable location in the back of a sunny border or along a wall?
• If your garden is windy, choose a sheltered spot and stake your plants as they begin to grow
• Single flowers are best to attract pollinators like bees and butterflies
• Hollyhocks are not long lived so always allow seedlings
  

  A seedling is a young plant grown from seed.

  to grow and keep the best plants and flower colours
• Choose colours that will compliment your other border plants

Go to RHS Find a Plant and search for Alcea rosea to browse the photographs and plant descriptions, and find out where to buy them.

RHS guide to identifying your soil type

RHS guide to assessing your microclimate

Buying a hollyhock

Hollyhocks are available as seed, small plug plants

Seedlings or young plants grown singly in small modules, with the advantage that they can be transplanted with minimal root disturbance. Bedding plants and young veg plants are often sold as plug plants of various sizes, with smaller ones requiring more aftercare. They usually need to be potted up and grown on indoors until large enough to plant outside.

and young plants in containers up to 2 litres in size.

Seed is widely available all year round in garden centres and online. There is a wide range of single and double flowered-forms, which are sold as mixtures or single colours. This an economical way to add these plants to your garden and the choice is more extensive than when purchasing plants.

Plug plants or young plants are available in spring, although the choice may be limited. You can buy them in garden centres or online.

RHS how to choose healthy plants

Where to plant

Hollyhocks will grow in any garden soil, but prefer fertile, well-drained soil, in full sun, to produce the tallest flower spikes. Choose a position that is sheltered from strong winds, else they tend to blow over.

When to plant

Pot grown hollyhocks are best planted in spring or autumn, but can be planted at any time, spacing them 60cm (24in) apart.

Plug plants

Seedlings or young plants grown singly in small modules, with the advantage that they can be transplanted with minimal root disturbance. Bedding plants and young veg plants are often sold as plug plants of various sizes, with smaller ones requiring more aftercare. They usually need to be potted up and grown on indoors until large enough to plant outside.

, bought in garden centres or online, are best grown on in 10cm (4in) pots to establish a good root system, before planting out into the garden.

If growing hollyhocks from seed sow indoors in mid- to late spring or directly in the position you want them to grow in May/June (See the Propagation section below for more details).

Watering

Water seedlings

A seedling is a young plant grown from seed.

and young plants regularly, ensuring the top 15cm (6in) of soil is damp but not soggy, in the first few months. After that, plants in the garden should only need water in prolonged dry or hot spells. See our guide to watering

Staking

If your garden is windy, place a bamboo cane

A cane is a slender, straight, length of woody plant material, usually bamboo. Canes are primarily used as plant supports. The fruiting stems of blackberries, raspberries and hybrid berries (such as loganberries and tayberries) are also known as canes, so these crops are often referred to as cane fruit.

or stout stake close to each stem and tie the stem to the support as it grows.

Feeding

Usually, plants growing in a good garden soil will not need additional feeding. Just improve the soil by adding a 10cm (4in) layer of well-rotted garden compost

Can refer to either home-made garden compost or seed/potting compost:

• Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

as a mulch

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

to the soil after planting.

Deadheading

Cut the flower spikes to the ground when the flowers have faded. If you want to save the seed, wait until the seed cases are brown before collecting the seed and then cutting down the stalks.

End of season care

Hollyhocks are full hardy and don’t require any special treatment over winter. Remove all dead leaves and discard plants that have been badly effected by rust disease (see problems below).

No pruning is required, just remove any leaves that are heavily infected with rust disease through the summer and cut down the flower spikes when the flowers have faded.

Hollyhocks are easy to grow from seed and will readily self-seed in your garden. The new plants may not be exactly the same as the parent plants, if they are hybrids or cultivars. Self-seeded plants can be lifted while young and transplanted

Moving a plant from one growing position to another, often from a pot to its final spot in the garden.

to a spot in your garden where you would like them to grow.

Seed: collecting and storing

Sow Hollyhock seeds indoors or in a greenhouse in spring (April/May). They germinate easily in temperatures of 16-21 ⁰ C (61-70⁰ F), so placing in a propagator

A propagator is a portable, lightweight structure usually plastic, with a vented or unvented lid to provide a humid, slightly warmer atmosphere. It is useful to help seeds germinate and root cuttings. It may have adjustable, thermostatic temperature control.

encourages germination

Germination is the process by which a seed develops into a new plant. It starts with the seed coat absorbing water, expanding and splitting, which allows oxygen and water into the seed so its food reserves can be broken down and used by the embryo for growth. The first root (called the radicle) pushes into the soil to anchor the new plant in place and start absorbing water and nutrients. The first shoot (called the plumule) then grows upwards, out of the soil, towards the light.

. If the seed pot is placed on a windowsill, germination is just a bit slower. See our guide to sowing seed in-doors

Alternatively, sow seeds directly in the ground where you want them to grow in May/June. Hollyhock seed can also be sown in autumn and the young plants over-wintered in a cold frame

Cold frames are glaze box-like structures made from brick or wood with a  hinged or removable, glazed, sloping lid. Useful to protect plants from cold weather over winter or acclimatise (harden off) young plants in spring and provide extra warmth for tender crops in summer.

or cold greenhouse, to flower the next year.

Young plants are suceptible to damage by slugs and caterpillers. Flea beetles can occassionally cause significant leaf damage.

Hollyhocks are susceptible to rust disease and plants should be replaced after a few years, to prevent a build-up of disease. Collect all dead and diseased tissue at the end of the season to reduce the carry-over of rust spores to the next year.