Sunflowers grow best with six to eight hours of full sunlight per day, in well-drained, nutrient-rich soil.
To ensure that your soil can support sunflowers, dig an area of approximately 60-90cm circumference and 60cm deep, in which you can place slow-release granular fertilizer with trace minerals. You can also add composted manure.
Once your soil is prepared with fertilizer and the area filled back in, you can start planting your seeds.
How to sow sunflower seeds
Sow the seeds into the garden rather than pots, as sunflowers have long roots that will suffer if they are planted in too small a space.
Rake your prepared soil to a fine, crumbly texture and create holes about 12mm deep for each seed. Leave a 10cm space between each one.
Water your soil, plant the seeds in the holes, and cover them up again with soil.
Cover the area loosely with netting to protect the seeds and keep them watered until they begin to sprout. This usually happens within 5-10 days.
When the first leaves appear, if the plants are too close together, remove smaller plants and leave the strongest, tallest plants about 45cm apart.
As your sunflowers grow taller, support the plant stems by tying stems loosely with string to a vertical cane placed next to the plant.
Feeding and caring for your sunflowers
Feed and water your sunflowers regularly, as they need lots of nutrients to help them grow to their full potential.
When the plants are small, water their roots about 10cm away from the plants themselves. Use about 10 litres of diluted liquid fertilizer solution each week.
As your sunflowers grow larger, create a small moat around each plant, about 45cm away from each plant sunflower and 10cm deep. Feed your sunflowers around 20 litres of diluted liquid fertiliser per week.
Make sure you don’t pour the fertilizer on to the plant’s stems, or they it rot.
Once your plant starts flowering, feed it with a high potash tomato feed.