Last updated on October 12th, 2021
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For flowers that make everyone smile and attract bees, birds and butterflies, sunflowers are remarkably easy to grow. You can start your sunflowers from seed in pots indoors or directly in the garden. Transplanting them to sun-filled locations and watering them adequately is all you need do to have these cheerful yellow, orange, dark red, purple or brown blooms emerge tall in your garden.
How do I grow sunflowers from seed?
Where do I get seeds from?
Sunflowers are easy to grow from seed – and this is the best way to produce strong, tall, vibrant plants. You have the choice of starting the seeds indoors in peat pots or planting them directly into the soil in your garden when the weather is right. You can buy seeds online or from your local garden centre, or harvest them yourself at the end of the growing season from local plants. In either case, make sure that you know how tall the plant is supposed to grow so you know if you have enough room for it.
Starting sunflower seeds indoors
- Fill small peat pots with a multi-purpose compost. Adding Vermiculite helps with drainage. You can also use standard 9cm pots, seed cell trays or even paper rolls as shown above.
- Plant one or two seeds in each peat pot, about 1.5cm to 2cm deep in the soil.
- Replace the soil back over the seed.
- Water the pots and cover them with a clear cloche.
- Place the pots on a windowsill in indirect sunlight.
- Water the compost frequently to keep it moist.
- After 10 to 14 days, the seeds should have germinated. Remove the covers now.
Starting sunflower seeds in the soil
The best time to plant sunflowers seeds outdoors is about two weeks before the last expected spring frost. This is usually in late April or Early May and gives the seeds time to germinate in cool weather.
- Create a shallow trench in the soil about 2cm to 4cm deep.
- Position individual seeds in the trench about 10cm apart.
- Cover the seeds up with soil and water them in.
- They usually sprout in 7 to 10 days.
How do I transplant sunflower seedlings?
Transplanting the seedlings into the garden from either the indoors peat pots or the outdoors seedlings are similar processes.
Into the ground
- Find the right location. Sunflowers need well-drained but moist, loose soil and a minimum of six hours of direct sunlight per day.
- Check the soil you’re transplanting into. If it’s sandy and/or lacks nutrients, add some slow release granular fertiliser according to the package instructions. Consider adding compost even if your soil is of a good quality.
- Harden off the indoors seedlings by taking them into the garden daily so they become used to the outside weather. Do this for two weeks, bringing them in at night-time.
- Select the strongest seedlings from the pots or the ground.
- Plant the seedlings in the prepared soil spacing the plants about 15cm to 30cm apart (depending on how large you expect them to grow) and 2.5cm deep.
- Water the young plants well (and often at the beginning); keep the soil moist but not waterlogged. Drainage is important.
- If the sunflowers become overcrowded, thin them out. It’s important that they have plenty of air flowing around them to keep them healthy.
Only dwarf sunflowers do well in pots as the other varieties grow much taller and can easily topple over.
- Choose a pot about 15cm to 20cm in diameter and make sure it has drainage holes in the bottom.
- Put a mixture of compost and vermiculite in the pot.
- Plant the seedling in the pot and water it in well.
- Note: pots dry out faster than soil in the ground so you need to water them more frequently. You may also need to fertilise the potted sunflowers to give them enough nutrients for strong growth.