How to grow sunflowers

Want to know how to grow sunflowers? They add instant colour and structure to a garden and are fun to grow with kids, so find out how to give it a go

how to grow sunflowers
(Image credit: Leigh Clapp)

They're guaranteed to raise a smile, and learning how to grow sunflowers from seed is super easy. Planting these glorious golden flowers is a great activity to do with children, especially as part of a competition to see who can grow the tallest.

In terms of garden design, as sunflowers are vibrant and quick-growing annuals, they are brilliant for adding instant structure and colour from June up until October. They look particularly effective if grown in rows or avenues supported by sturdy wooden stakes, or along a sunny south facing wall. 

Sunflowers also make great cut flowers for bringing indoors. Although we tend to think of them as giant yellow dinner-plate flowers, they also come in a spectrum of lemon yellows, reds and browns and even through to purple, which can make for a spectacular floral display.

Sunflowers are great for the environment, too. They are fantastic pollinators and attract many insects and bees, plus, once the flowers are over the oily seeds can be harvested and make great bird feed.

Read on to see how to grow your own below, then head to our garden hub for more wonderful planting ideas.

Which sunflower seeds should I choose?

Which variety of sunflower seeds you choose will depend on what you want to use them for. For growing with children or against garden walls try the giant varieties such as Giant Russian or Mammoth which can grow up to 3m tall. Larger varieties will need sturdy stakes in place to help support them. 

Alternatively, for container planting or patios or borders try dwarf varieties which are more bushy and have multiple branches. If planting for cutting try a mix of different varieties such as Marshall's Vincent's Mix and if bringing indoors it might be worth considering pollen-free seed varieties.

How to grow sunflowers

If frost is still a risk you need to start sunflowers from seed either inside or in a greenhouse. Once they germinate, you can plant the saplings outside. Here's how...

sunflower

Sunflowers work well planted against buildings or walls, brining tall structure to the backdrops of planting displays

(Image credit: Leigh Clapp)

How to sow sunflower seeds

Sunflower seeds can be sown undercover in March in small pots or seed trays, or from April to May they can be directly sown into the ground. It's always best to follow specific advice on the seed packet, but here are some general guides. 

sunflower

Certain varieties of sunflowers can great cut flowers 

(Image credit: Leigh Clapp)

Sowing in pots

You will need:

  • Sunflower seeds
  • 7.5cm plastic pots
  • Multi-purpose compost
  • Plant labels
  • Pencil or permanent marker pen 
  • Watering can with rose
  • A clear plastic bag or bottle

Method:

1. Fill your pots with compost and firm down gently

2. Create a small hole in each pot or with your finger (no deeper than 1.5cm) and drop in the seed

3. Fill over with compost

4. Give them a good water with the watering can, ideally with a rose to prevent flooding the pot

5. Make sure to tuck a label into the side of the pot. 

Tip: use a permanent maker as regular watering can easily wash off labels in water-based ink

6. Cover the pot with a clear plastic bag or you can use a clear drinks bottle cut in half. For best chances of germination place the pots in a greenhouse or somewhere indoors where they can get overhead light, alternatively a sunny windowsill will do

7. Water regularly so that the soil is always moist. You should notice seedling appearing in 1–2 weeks

8. Once the shoots are too big for the pot they will need replanting. Before planting the seedlings out into beds or larger pots on the patio the plants will need hardening off. Move the seedlings in their pots outside for 2–3 weeks to allow the plants to acclimatize before planting them in their final position

Sowing outdoors

From April–May, once the last frost has passed and the soil is warm, sunflower seeds can be sown directly into the ground. Planting in pairs is usually recommended to increase chances of germination. 

You will need:

  • Rake
  • Wooden pegs
  • String
  • Sunflower seeds
  • Watering can with rose

Method:

1. Prepare the seed bed in advance by digging over the soil until fine and finish by raking over to level the surface

2. Use pegs and string to mark your sowing line across the bed and remember to pop in a label at one end

3. At 30cm intervals make 2 holes about 1cm in diameter and about 10cm apart, sow the seeds and cover over with soil

4. Give them a good water with the watering can

Tip Sunflower seedlings are prone to being attacked by slugs. To combat this protect them with cloches or lay down slug pellets

5. If the plants start to get crowded as they grow, thin them out by removing some seedlings (this may seem brutal, but needs doing so that survivors can get optimum growing conditions)

Tip If growing for cut flowers pinch out the tip when the plants get to about 20cm tall, this will encourage branching and more blooms

6. Plants approaching up to 1m high will need staking to support their stems. Use wooden stakes around 1m high and hammered into the ground

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