Sunflower Sowing and Growing Guide

Sunflower growing guide

When?

Sunflowers can be sown throughout the spring and early summer months. Sowings indoors can begin in April and continue until early May. Sowings outside, directly in the soil or patio pots can be made from mid-May until late July for dwarf varieties like ‘Desire Red’ or ‘Tiger Eye’. Outdoor sowings are best protected with some horticultural fleece until the threat of frost has passed.

Germination?

A kitchen windowsill or a heated propagator is perfect for germination. It is best to use small pots (7cm) or large celled plug trays – filled with a seedling specific compost. Make sure you moisten the compost before planting your seeds. Plant seeds individually in each pot or cell about 1cm deep. Cover the seeds with a plastic bag if they are on a windowsill – this will keep the conditions warm and moist. If your seeds are in a heated propagator this won’t be necessary.

Sunflowers only need a few days for germination at a moderate temperature between 16-18 degrees Celsius.

Transplanting?

Prepare to transplant your seedlings after about 4-5 weeks. Your seedlings can be planted outside in the soil or in patio containers from mid-May onwards. Plants can be kept in a non-heated greenhouse/cold frame before the middle of April and planted outside from mid-May but protection from frost is necessary. Seeds sown directly in the soil or pots outside will take around 4-5 weeks to emerge, depending on ambient temperatures and can be left in situ to grow and flower.

Where?

Once your sunflowers start to outgrow the smaller 7cm pots, you can move them into their final position in the garden. Choose a sheltered sunny location if possible although the new dwarf types will prosper in most positions if they have adequate sunlight, i.e. not in the shade. Both ‘Tiger Eye’ and ‘Desire Red’ take 8-10 weeks to flower but taller types can take 12-14 weeks before they bloom. Remove dead flowers to encourage continuous blooming from side branches and look forward to a colourful display for 8-10 weeks after first flowers develop.