How to grow sunflowers

Annual sunflowers bloom from summer to autumn. Depending on the variety, they take 11-18 weeks to flower from seed. With that in mind, it's a good idea to sow sunflower seed every couple of weeks, so you'll have a constant supply of cheerful blooms throughout summer.

Sunflowers are easy to grow from seed and are ideal for growing with children. They can reach heights of up to 3m, bearing impressive, long-lasting flowers, and look fantastic in gardens and allotments. They also make an excellent cut flower.

Did you know? Sunflowers are related to Jerusalem artichokes, Helianthus tuberosus. If you plant Jerusalem artichokes they will bear beautiful, sunflower-like blooms, provided conditions are hot enough and they receive enough sunshine.

How to grow sunflowers

Growing sunflowers from seed is easy – you just need a sunny, sheltered spot and good soil – add some well-rotted manure or garden compost before planting to enrich your soil, if necessary. Protect the young plants from slugs and snails, and water regularly. You may also need to stake them if they're in an exposed position.

Choose your variety carefully as dwarf sunflowers grow to around 50cm, while taller varieties can reach up to 3m in height. Sow seeds in pots from April and plant out a few weeks later. Water frequently and, if growing for height, feed weekly with a nitrogen-rich fertiliser to encourage them to grow tall. You may need to stake some of the taller varieties.

Sunflowers: jump links

• Where to grow sunflowers
• How to care for sunflowers
• How to propagate sunflowers
• Sunflower problem-solving
• Growing sunflowers: buying advice
• Types of sunflower to grow

More on growing sunflowers:

• How to plan for year-round colour
• Unusual sunflowers to grow
• Five-minute fun: growing sunflowers with children

Where to grow sunflowers

Sunflowers need sun. For best results, grow them in rich, fertile soil in a sheltered, sunny spot.

Sunflowers grow well in pots but if you're growing for height, it's best to grow them in the ground.

When to plant sunflower seeds

The best time to plant sunflower seeds is between April and May. Sow seeds individually in 10cm pots of peat-free, multi-purpose compost. Cover the pots with a clear plastic bag and place them in a warm spot for the best chances of germination. Remove the plastic cover once the seedlings have emerged. When the seedlings are large enough to handle, harden them off gradually - for about two to three weeks - then plant them outdoors. You may need to protect them from slugs and snails. Alternatively just sow the seeds direct from mid-April onwards.

How to plant sunflowers

If your garden has a lot of slugs and snails, your sunflowers may benefit from being potted on into larger pots of fresh compost, then hardened off before planting out into the soil. This means the plants will be bigger when in their final growing positions, and therefore more resilient to slugs and snails. Regardless of how big they are, don't plant seedlings out until the soil has warmed considerably and the risk of frost is gone.

Watch Monty Don sow sunflower seeds as part of his giant sunflower trial, in this clip from Gardeners' World:

When planting out, prepare the soil by removing weeds and if necessary add plenty of organic matter such as compost or well-rotted manure. Plant the sunflowers at the same depth they were in the pot. Water well and stake taller varieties with a bamboo cane or similar.

Here, Monty plants out his sunflowers and explains how to stake them:

Growing sunflowers in pots

Sunflowers do well in pots, although they usually don't grow as tall as those growing in the ground. Sunflower plants are heavy feeders, so make sure you water the pots regularly (daily in hot weather) and feed fortnightly with a nitrogen-rich fertiliser, switching to a high-potash fertiliser, such as a tomato feed, when the plants begin to bloom.

To grow sunflowers in containers, sow the seeds in small pots as you would normally in spring, and then transplant them individually into larger ones when they're large enough to handle, eventually potting them on into a 30cm pot of loam-based, peat-free compost, ideally with added organic matter. Stake taller varieties as you would for plants growing in the ground.

Caring for sunflowers

Annual sunflowers need plenty of water and will suffer if allowed to dry out. If you're growing for height, feed them fortnightly with a nitrogen-rich fertiliser and then switch to a potash-rich tomato feed just before flowering.

Stake tall varieties with a sturdy cane to prevent wind rock, especially if growing in an exposed position.

After flowering, leave the faded flowerhead intact so the birds can feast on the seeds. Once they have eaten their fill pull out the entire plant and put it on the compost heap, chopping up the thick stem so it will rot down more quickly.

Find out which sunflower fares best in Monty's giant sunflower trial update:

How to propagate sunflowers

After flowering, sunflower heads develop masses of seed. You can harvest these to use in cooking, but bear in mind you will need to remove the tough seed coat before eating. Better still, remove the seeds from the seedhead and leave them to dry for a few days, before storing in a paper envelope in a dry spot, so you can sow them the following year. Make sure you leave some seeds for the birds, too.

Growing sunflowers: problem solving

Sunflowers are generally trouble free but young seedlings are susceptible to slug and snail damage. If your garden has a lot of slugs and snails, avoid planting sunflowers until they are big enough to withstand being attacked. If growing sunflowers in a greenhouse or cold frame, then regularly inspecting and removing slugs and snails can be effective. Also consider using wildlife-friendly copper tape to keep molluscs at bay.

Sunflowers to grow

Sunflower ‘Russian Giant’

'Russian Giant' is a huge annual sunflower, bearing a single flower and growing as high as 3m. This traditional yellow-flowered variety blooms from July to September.

Height x Spread: 3m x 60cm

• Buy sunflower 'Russian Giant' from Thompson & Morgan

Sunflower 'Shock-o-lat' F1

This red-flowered sunflower bears large flowerheads with bronze-red petals with yellow tips and a red-brown central boss that yields edible seeds. The stems have a purple tinge, which contrasts well with the green of the leaves.

Hx S: 2m x 60cm

• Buy sunflower 'Shock-o-lat' from Dobies

Helianthus ‘Lemon Queen’

This perennial sunflower bears masses of small, lemon-yellow blooms from July to September, and comes back year after year.

H x S: 2m x 45cm

• Buy sunflower 'Lemon Queen' from Crocus

Sunflower 'Choco Sun'

One of the best dwarf sunflowers to grow, 'Choco Sun' is fast growing and bears masses of large yellow flowerheads. It's a perfect sunflower for pots and fun for children to grow.

H x S: 35cm x 35cm

• Buy sunflower 'Choco Sun' from Thompson & Morgan