Sunflowers are one of the brightest (and tallest) flowers around, and instantly add bold color to boring gardens or outdoor spaces. What’s more, they’re one of the easiest flowers to grow, so it won’t be hard to learn how to plant sunflower seeds and when to do it.
Otherwise known as Helianthus, the sunflower is native to North America, and has over 70 different varieties. Sunflowers are also known to grow to giant heights of up to two metres, and they come in a wide range of colors including rusty red, orange, green and even white.
The best time to plant sunflowers is between April to May, or when the soil gets warmer. (We've got more on what you should plant in May for summer blooms.) While most sunflowers germinate once the soil reaches temperatures of 70 to 80 degrees F, you can either sow the seeds in pots first or directly into the garden. What’s more, learning how to plant sunflower seeds and watching them grow is fun for children.
So if you want to add vibrant, warmth to your outdoor spaces, here’s how to plant sunflowers from seeds.
How to plant sunflower seeds in trays or pots
Seed trays or pots
Trowel or gardening fork
Plant label and pen
1. Prepare your seed trays/pots — First, fill the seed tray with some peat free multi-purpose compost, leaving 1cm at the top. Place one seed into each seed pot, and push down gently into the compost. If you are using a seed tray, spread the seeds approximately 5cm apart.
2. Place in sunny spot — Lightly cover the top with extra compost before watering well with a watering can. Add a plant label before placing the tray in a warm sunny spot. Sunflowers thrive in the sun, so it’s best to place them near or on a windowsill.
3. Transfer to bigger pots — Once your seedlings have germinated and have reached a height of 2 inches, carefully remove each seedling and transfer to bigger, individual pots. Add more compost to the pot to secure the seedling. If you’re having trouble getting the seedling out of the seed tray, use a blunt knife or tool to gently loosen the soil.
4. Water well and transfer — Once your plants have reached 12 inches in height, you can plant them outdoors in a sunny location or move them to a bigger pot if you don’t have garden space.
TOP TIP: Water sunflowers regularly and don’t let them dry out. You can also feed fertilizer to sunflowers once a week to encourage growth.
How to plant sunflower seeds in the ground
1. Choose a well-lit spot — First, find a sunny and well-drained location in the garden before preparing the soil. Remove all weeds and rake the soil into a fine crumbly texture.
2. Prepare the soil — Dig small trenches in the soil around 2.5cm deep for each sunflower seed, leaving a 10cm gap between each one. Then place one seed into each hole and cover with soil.
3. Water seeds well — Water completely with a watering can. Ensure the seeds keep well watered until they start to sprout.
4. Support stems — As sunflowers start to grow and become taller, use stakes or canes to support the stems by loosely tying them together with some string. This will protect the plant from strong winds and keep the stem strong and vertical.
TOP TIP: If you love the sight of sunflowers, sow a few seeds every couple of weeks. Then you’ll have bright and cheerful flowers from early summer right until the end of autumn.
How long do sunflowers take to grow?
Generally, it takes between 80 and 120 days for a sunflower plant to grow and develop seeds. But, this will depend on the variety of sunflower and the conditions, as each type will grow at a different rate.
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