Sunflowers are happy, summery flowers and so easy to grow. This is a great garden project for children and adults alike. Kids love a competition to see who can grow the tallest sunflower!
Sunflowers are tall plants with big daisy-like flowers that come in yellow and red tones. They have brown centres that turn black as they develop into seed heads. They tilt their flower heads to follow the sun around the sky during the day.
Sunflowers are great for wildlife as many garden birds love to eat sunflower seeds. Or you can harvest them for yourself.
Grow sunflowers in full sun in a sheltered spot – preferably against a wall or fence. This protects the long stems from the wind so they don’t get blown over.
They prefer well-drained soil that’s rich in nutrients, so add some peat-free compost or slow-release fertiliser to the ground before you plant.
How to grow sunflowers
The easiest way to grow sunflowers is to sow them directly in the ground where you want to grow them! Dig over the soil and remove any weeds. Rake the surface to a fine crumbly texture. Sow the seeds 12mm deep and 45cm apart, and water in.
Sow seeds outdoors from mid-April to May when all risk of frost has passed. Keep the ground moist while the seeds germinate and protect seedlings from slugs. You can put down barriers such as copper tape, set beer traps or physically remove slugs to keep them under control, or cut the bottoms off plastic bottles and use them to cover the seedlings.
How to sow sunflower seeds indoors
You can also sow sunflower seeds indoors first. Fill individual pots with seed peat-free compost and sow the seeds 12mm deep on their sides. Water well and keep somewhere warm until they germinate.
When the seedlings have two sets of leaves, begin hardening them off. Take the pots outside on warm days and bring back in at night. Continue this for a week to acclimatise the plants to outdoor conditions. Then plant them in prepared soil in the garden and water well.
How to care for sunflower plants
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Make sure to water your sunflowers as they grow. Sunflowers have deep root systems, so once a week or less, thoroughly soak the soil around the roots to give the plants a boost.
As the plants grow taller, they may need staking to support the tall stems. Push a bamboo cane into the soil and loosely tie the stem to it. Check the ties don’t get too tight as the plant grows.
How to harvest the flowers
If you want to use the sunflowers in vases, cut them early in the morning and display in tall containers that support the flower heads. Change the water regularly to keep them fresh.
Many people also want to harvest the tasty sunflower seeds. To do this, allow the seeds to mature on the plant. Cover the flower heads when the petals wilt with a thin layer of horticultural fleece to stop birds stealing the seeds.
As the seeds develop, the flower head will droop and the seeds will swell. They are ready when the back of the flower head turns brown and the seeds darken. Cut the flower head off the plant and remove the seeds.
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David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.