Sunflowers will grow taller and reach 'great heights' if you add 1 thing to the soil

Sunflowers are big, bright and bold, and look beautiful in summer when they grow tall and large. The large yellow are hugely beneficial to your home's , supporting pollinators and providing food for species of birds like greenfinches and chaffinches.

Sunflowers are considered fairly resilient and are easy to grow. However, they can fail without the correct care. As we enter sunflower season, Lucy Taylor, expert at , has explained how to properly care for sunflowers to avoid them wilting, falling over, or dying.

"Sunflowers, more formally known as Helianthus annuus, are spectacular, colourful flowers that are known for being both easy to grow and reaching great heights in gardens and outdoor spaces," she said.

"They also play an important role in helping to create a wildlife-friendly garden, with their seeds providing food for a variety of visiting birds.

"With more than 70 different varieties of sunflowers, many people want to choose the best sunflowers for gardens. Different sunflower varieties will grow to different heights and tend to require different environments and levels of care."

How to take care of sunflowers

Plant in direct sunlight

Sunflowers need lots of sunlight to be able to grow. Around six to eight hours of direct sunlight per day is ideal, especially for bigger varieties.

Lucy added: "Ideally, choose areas that are south-facing and sheltered from the wind. If you are unable to do this, use a stake to support stems growing in more exposed areas. If you're initially sowing the seeds under cover in pots, they'll thrive in a greenhouse or very well-lit windowsill. When sowing seeds or re-planting in the ground, choose a spot that gets a good amount of sunlight."

Use nutrient-rich soil

"Sunflowers need a lot of nutrients to grow their bright petals and seeds, particularly if you're growing larger varieties," says Lucy. Your soil should be nutrient-rich; if you're planting under cover or in pots, you'll want to use peat-free multi-purpose compost. If you're planting outside, it's advisable to dig in organic matter or aged manure."

If this isn't possible, work a slow-release fertiliser into the ground. Dig this in when planting, around 20cm (8'') deep into the ground, ideally. Depth is very important here, and this will ensure there's plenty of food available for your sunflower's long roots.

Peat-free multi-purpose compost to drain soil well

"To maintain your sunflowers, ensure your soil drains well," advises Lucy. "Heavy clay soil can retain water, which can lead to irrigation problems and cause root rot for sunflowers."

If your garden has clay-heavy soil, dig in peat-free multi-purpose compost into areas where you are planting."

Give sunflowers lots of space

"Sunflowers need space from all angles to grow properly. If dug into flower beds or planted in pots, make sure there is enough depth for their roots," says Lucy.

Most varieties will need at least 20 cm (8'') to grow down. When sowing seeds, thin them to around 30cm (12'') apart for dwarf varieties, and 1m (3ft) apart for taller varieties. If you are planting taller varieties, make sure they have enough space to grow upwards to their potential tallest height.

Consider staking certain sunflowers

"Not all sunflowers need to be staked. However, some tall varieties that are likely to be exposed to frequent winds can benefit from being supported, to prevent them from falling," advises Lucy.

If you are planting sunflowers in areas where there is less than ideal sunlight, you could also consider using a stake for additional support for sunflowers which are unable to grow a strong stalk, the expert added.

"To stake a sunflower, you can tie it to a cane, a solid stick or a fence," she said. "Use a thin piece of twine to attach the stake to the stem of the sunflower, tying the two with a figure-of-eight motion. If needed, attach it in a few different areas along the height of the stem."

How to water sunflowers

Keep the soil moist

Sunflower seeds take around 10 days to germinate if kept in the right conditions. Keeping the soil moist is especially important at this stage. If you are planting them undercover first, water them daily so that the soil is moist but not wet, and ensure seedling pots are well-drained.

To retain plenty of moisture at this stage, cover pots in cling film. Sunflowers planted outside need to be kept moist with rainfall and irrigation. The three weeks after they have bloomed are the most important for keeping them watered, as this will develop the thickness of their stems. Be wary of the soil dampness after rainfall, and add more water if it is too dry during periods of low precipitation.

Water sunflowers at least twice a week

Ensure growing sunflowers are watered with rain, or by you, at least twice a week. Check the soil around the root area regularly; if it feels cool to the touch, it is moist enough. If planting sunflowers during late April into May, when rainfall is higher, the soil and pots must drain properly. Aside from using good quality, peat-free compost, if you are planting in pots, you should ensure they have adequate drainage systems to avoid root rot.