Top of the Crops - Sunflower

Sunflowers simply say “summer,” announcing to everyone near and far that the sun and heat have arrived. These towering beauties may be native to North America, but there is no reason why you can’t successfully grow them here in the UK.

They are a robust and hardy plant, resistant to pests and tolerant of high temperatures. In fact, they like the heat so much that it is a good idea to start them off in a polytunnel to keep them warm.
Sunflowers are an annual crop, and they have a big flower that matures into a head filled with these useful seeds. Bright yellow (and less commonly, red) petals surround a rich brown centre and cheer everyone up in the vicinity. Their love for sun is scientific – they are ‘heliotropic’ – this means that they turn their flowers to follow the sun as it moves across the sky. What a perfect ambassador for summer, and you can even harvest, toast and eat their delicious seeds!

These beauties are tall and coarse, with tuberous (creeping) roots and bristly leaves. They can grow up to 5 metres in height, but one record-breaking specimen in the Netherlands topped 10 metres! If you don’t have this kind of space, don’t worry – varieties have been developed for containers and smaller spaces.

As long as you do not waterlog your soil, sunflowers are easy and fun to grow. They attract many bird species and bees to your garden, and look smashing cut and arranged in a vase. They also make a stunning and special gift when you visit friends and family – everyone loves getting a bouquet of sunflowers.


Growing Sunflowers In a Polytunnel

It’s no secret that sunflowers love heat and light, and so a polytunnel can help keep them warm in the UK, without damage from the beating sun. Polytunnels are comprised of an elongated, semi-circular tunnel frame, covered and fitted with polyethylene. They are available in a wide array of sizes and shapes, including those that are well suited to sunflowers.

Their main purpose is to create a microclimate beneath their cover in order to provide and maintain higher temperatures and humidity. This allows you to start sunflowers earlier than you would otherwise be able to do in the often chilly, rainy UK. Polytunnels protect your sunflower crops from cold, wind and rain, ensuring that they thrive.


How To Grow Sunflowers

Prepare the site :

  • Choose your planting site – Sunflowers like a lot of direct sunlight, so place them in a location where they will get 6 to 8 hours of sun per day. You must also accommodate their long tap roots – they really do need to stretch out in well-dug, loose, and well-draining soil.
  • Prepare the bed – Dig down approximately 2 feet down, and 3 feet across. This will ensure that the soil isn’t too compacted. Make sure that the area drains well.
  • Choose your soil – Sunflowers are not very picky, but they do best in slightly acidic to slightly alkaline soil (a pH of 6.0 to 7.5).
  • Ensure that the soil is fertilised – Sunflowers need nutrient-rich soil that is laced with organic matter or composted manure. You can also work slow release granular fertiliser in the soil, approximately 20 cm.
  • Use a polytunnel - A polytunnel can be used to shelter your sunflowers from strong winds and rain.

Planting your sunflower seeds :

  • Spring is best – You can start to sow your sunflower seeds directly into the soil once the last frost of the year has passed. If you are worried about another frost, make sure that you use a polytunnel. You want to soil to be approximately 13–16°C for the best results.

  • Give them plenty of room – All sunflowers need a lot of room to thrive,  especially the low-growing varieties that will branch out over time. Your rows should be about 75 cm apart.

  • Planting the seeds – Plant your seeds approximately 2 – 3 cm deep, and around 20 cm apart. Some gardeners like to plant multiple seeds and then thin them down so that only the strongest contenders are left.


Caring for your sunflowers :

  • Watering – When your plant is still small, water the root zone a few cm around each plant. Once your plant is established, you should revert to watering infrequently – this encourages deep rooting.
  • Slugs and snails – These pesky pests love sunflower plants, so you can place slug bait around the stem to protect them in their nursery stages.
  • They do not need much fertiliser – Sunflowers will not thrive if you fertilise them too often, as their stems will break in the autumn. If you do want to fertilise, add a little bit of diluted fertiliser into your water and keep it away from the base. You can instead build a moat around the plant about 20 cm out.
  • Tall sunflowers need support – As your sunflowers grow and thrive, they will need support. You can use bamboos sticks or stakes.

How to Harvest Sunflowers

Once it is time to harvest your sunflowers, cut the main stem just before the flower bud has opened – this will encourage them to bloom to the side (which looks great in an indoor bouquet. It is best to cut the stems first thing in the morning – if you harvest in the middle of the day they will wilt faster. Display them in a tall container that gives them enough support for their blooms. Changing the water daily will keep them looking their best for longer.

As one of the most beloved flowers on the planet, sunflowers are a cheerful and attractive addition to any garden. Consider adding some to your crop this year.


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