How to Grow & Care For Sunflowers

Where to Plant Sunflowers

Believe it or not, sunflowers need lots of sunlight to be able to grow! Around 6-8 hours of direct sunlight per day is ideal, especially for bigger varieties.

If you’re initially sowing the seeds under cover in pots, they’ll thrive in a greenhouse or very well-lit window sill.’. When sowing seeds or re-planting in the ground, choose a spot that gets a good amount of sunlight.

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.

Best Soil Conditions for Sunflowers

Sunflowers are particularly hungry plants; they need a lot of nutrients to grow their bright petals and seeds, particularly if you’re growing larger varieties.

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.

To maintain your sunflowers, ensure your soil drains well. 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.

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. 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.

Staking 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 down.

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.

To stake a sunflower, you can tie it to a cane, solid stick or fence. 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, attachit in a few different areas along the height of the stem.

Sunflowers need different amounts of water depending on which stage of the growing process they are in. For example, germinating sunflower seeds need more water than established plants.

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 clingfilm.

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.

Established sunflowers need less water than seedlings, but the soil should never be dry. Sunflowers are partially drought-resistant but will dry out with extended periods without water, and as well as smaller, duller flowers, this can lead to stems drooping, which can be difficult to correct.

Sunflower seeds are a nutritious source of food for many animals, including humans.  They are also a rich source of energy, protein and natural fats for garden birds, many of which will eat them directly from flower heads.

The best time to harvest sunflower seeds is when the head of the sunflower has turned dry and papery. At this point, you will likely notice that seeds start to drop from the flower head naturally. To harvest these, place a bucket or another vestibule directly beneath to catch fallen seeds. To harvest the rest of the seeds from the flower, cut the sunflower heads from the stalk. The best time to do this is at the end of their bloom cycle, which usually falls in October.

Using a sharp knife, cut an inch below where the head meets the stalk. Place cut heads in a bucket, and then add in lukewarm water so that the flower heads are fully submerged. Leave these for around an hour and the seeds will have come loose from the flower heads. Dispose of heads, stalks and petals in your garden compost or green waste bin.

Once seeds are removed, allow them to dry fully by placing them on a large cloth in the sunlight. Once they are completely dried out, you can remove the outer layer of the seeds (the husks) of the seeds by rubbing them between your hands. This will expose individual seeds (also known as sunflower hearts).

While some birds will readily eat whole sunflower seeds, with the husks intact, some species are unable to crack into them. To cater for a wider variety of birds, include sunflower hearts in your bird food selection.

At Vine House Farm, we plant seeds at specific times every year, to ensure optimum growth and summer blooms.

We drill black sunflower seeds during May, depending on the weather and the wetness of the ground.

We harvest our sunflower seeds in October. Waiting until this time means the sunflower heads have gone brown and are waiting to die off, and the seeds have dried.

We grow over 100 acres of sunflowers on our farm each year, and when in full bloom the fields of bright yellow are a truly stunning sight. So it’s well worth a visit to our farm in Deeping St Nicholas to join one of our Sunflower tours, during August – see here for details.