How to Grow Sunflowers 

Tall and bright, sunflowers are one of the summer’s most popular plants. Not only are sunflowers incredibly easy to grow they are also quick to flower. Most varieties flower within 95 days of germination. As well as being quick to flower sunflowers are also heat tolerant and pest resistant.

While the tallest varieties can reach over 16 ft in height, if space is limited there are a number of compact dwarf or bush varieties available. This means that anybody can enjoy learning how to grow sunflowers. And if you want something a little different, as well as the typical tall yellow blooms there are also red, maroons, brown and orange flowering varieties.

A member of the asteraceae family along with marigolds, coneflowers, dandelions and asters, young sunflowers are heliotropic plants. This means that the flower follows the sun through the sky. As the seeds develop in the center of the flower the bloom becomes heavier and the plant loses this habit.

Instantly recognizable, learning how to grow sunflowers is a great way to bring color and drama to your garden. 

Did you know that the sunflower’s botanical name, Helianthus annuus, is derived from the Greek? Helios which means sun and anthos, the Greek word for flower.

If you want to learn how to grow sunflowers, this guide will take you through everything you need to know.

Different Sunflower Varieties

Before embarking on your how to grow sunflowers journey you must first decide what variety of Helianthus you want to grow. As I have already noted there are a range of different varieties available, meaning that even people with just a few pots on a balcony can enjoy the bright, vibrant blooms of the Helianthus.

Some of the most popular varieties include:

• Mammoth, this is a large, traditional looking flower. Reaching over 12 ft, it’s seeds are popular with birds or as a healthy snack.
• Teddy Bear only reaches a height of 3 ft making it ideal for pots and small gardens. The pompom-like golden flowers also look great in cut displays.
• Sunrich Gold is another great cut flower, producing pollenless 5 inch golden flowers with a green-yellow center. The plants reach a height of about 5 ft.
• Autumn Beauty is a spectacular cultivar reaching up to 7 ft. It produces flowers in shades or bronze, yellow and mahogany.
• Russian Giant is another tall variety, reaching over 10 ft, known for its bright gold flowers.
• Red Sun reaches a height of 6 ft and produces rich red flowers with balck centers.
• Vaentina reaches heights of 5 ft. it produces creamy yellow blooms.
• Dwarf Yellow Spray is another reliable cultivar. A bushy plant, it reaches a height of about 2 ft and produces eye catching yellow flowers.

As well as the typical tall, yellow varieties Helianthus come in a range of colors and sizes. 

It is easy to learn how to grow Helianthus from seed. Garden and DIY stores sell seed packets, but if you want something a little different or unusual you may need to order the seeds from a seed company or nursery. When purchasing your seeds always buy them from a reputable business or company.

If you aren’t sowing all the seeds in one go or successively during the spring and summer you can store excess seeds for use the following year.

How you store seeds affects their longevity. Store the seeds in an airtight container and keep in a cool, dry place until you are ready to use. While this helps them to keep for a few years, as seeds get older they lose their viability meaning that germination becomes more difficult.

How to Grow Sunflowers from Seed

Learning how to grow sunflowers from seed is pleasingly straightforward. These hardy blooms are suitable for USDA zones 2 to 11.

Sunflowers grow best in sunny spots, filled with direct lots of direct light. Ideally the plants should receive 6 to 8 hours of direct light every day. The soil should be loose and well draining. There are a number of ways to improve heavy soil before planting.

While the pH should, ideally range between 6.0 and 7.5 the plants can grow in conditions outside this, just avoid anything too extreme. If you don’t know the condition of your soil I would recommend using a soil test kit to find out. These are easy to use and provide you with a wealth of valuable information that makes cultivation plants a lot easier.

Learning how to grow from seed is pleasingly straightforward, just wait until the soil has warmed up before beginning. 

If you are sowing into pots or plants, fill the container with fresh multipurpose compost or potting soil. Make sure your container has lots of drainage holes in the bottom and is clean from both pests and dirt.

Dig the soil over to a depth of about 2 ft before planting. This helps to loosen the soil and gives you the opportunity to work in lots of organic matter such as composted manure or slow release granular fertilizer.

Your chosen spot should also have some shelter from the wind. This is particularly useful if growing taller varieties. Otherwise you will need to provide some form of support such as a bamboo stake.

How to Sow the Seeds

Sow the seeds directly into the garden or containers once the last frost has passed and the soil is at least 50 ℉.

Plant the seeds one to one and a half inches deep. Space them at least 6 inches apart. If you are sowing lots of the flowers, rows should be spaced at least 30 inches apart. While smaller varieties can be planted more closely together aim to give the plants lots of room to grow into.

After planting, water and apply a light dose of fertilizer to help encourage root production. This can either be watered or worked into the soil.

Remember to provide protection from destructive slugs and snails. How you do this is up to you. Some people like to use chemical controls while others, myself included prefer organic methods such as copper wire or sawdust and eggshell barriers. Finally, you may need to cover the soil with a net to prevent birds from disturbing the soil and digging up the seeds. Garden Netting is easy to use not only protects plants from small pests such birds but also from larger pests such as deer.

As the seeds germinate and grow, you must decide how to best protect them from destructive pests such as slugs and snails. 

Following germination keep the soil moist.

Gardeners in cooler climates can also start the seeds undercover in biodegradable pots, such as GROWNEER Peat Pots. Fill the pots with fresh multipurpose compost and sow one seed per pot, as described above. Following germination allow the plants to develop at least one set of true leaves before hardening off and planting out.

If you have started the seeds in biodegradable pots, dig a hole in the soil large enough to hole the pot. Place the plant still in the pot in the hole and cover with soil. As the plant grows the pot breaks down, allowing the roots to spread.

As long as you can provide fertile soil and lots of sun learning how to grow sunflowers is easy.

How to Care for Growing Sunflowers

Learning how to grow sunflowers is made easy by the fact that they are incredibly low maintenance.

When the plants are young keep the soil around them weed free. Weeds are quick to grow and can deprive flowers of valuable nutrients and moisture, stunting their growth.

When to Water

Knowing how often to water your plants can be difficult. Helianthus plants require lots of water. Even apply about an inch of water every week if it is dry. Try to keep the top 6 inches of soil evenly moist, don’t allow it to dry out.

Water evenly around the root zone when the plants are small. Use a hose to water in a circle about 3 to 4 inches wide all around the plant. This encourages the roots to spread out and evenly develop.

Once established water deeply to encourage deep root development. A large, extensive root system helps to prevent wind damage.

Fertilizing Your Flowers

Don’t over fertilize your flowers. This can cause stems to weaken and snap. If you have planted in an already enriched soil there is no need to further fertilize your plants.

If planted in rich soil, sunflowers require little regular fertilizing. However a potash feed can help to sustain flowering.

If you want to grow a really tall flower you may decide to apply a nitrogen rich fertilizer. While this can encourage growth it can also delay or prevent flowering.

To sustain the plant once flowers emerge a high potash feed, such as tomato fertilizer can be applied once a week but isn’t necessary.

How you fertilize your plants is up to you, however iIf you are using a liquid fertilizer try not to apply the solution too close to the base or stem. Slow release granular fertilizers, spread evenly over the soil, can also be applied.

Pinching Out

I have never pinched out my sunflowers but I know some gardeners like to. Pinching out helps to encourage new stems to grow. If you want to maximise the height of the plant don’t pinch out the growing tip. Doing so stunts growth. However, if you want lots of flowers pinching out the growing tip encourages more buds to form.

If you are unsure how to pinch out, simply remove the growing tip. You can either cut it away or literally pinch it out with your thumb and forefinger once the plant is about 8 to 10 inches tall. Following this the plants will rarely exceed 7 ft in height but will produce lots more flowers.

Companion Plants

Companion planting is the practice of growing mutually beneficial plants close together. This helps to encourage healthy growth as well as keeping plants healthy. It can also be used to encourage beneficial insects and discourage destructive pests.

Many people like to grow sunflowers alongside squash and sweetcorn and are believed to increase yields.

Sunflowers also attract ladybugs and other beneficial pests which prey on more harmful pests such as aphids. Planting these colorful flowers close to a bug hotel is a great way to encourage lots of beneficial insects to your garden. If you would like to learn how to build your own bug hotel this is a good guide.

Avoid planting near potatoes and pole beans. Sunflowers can inhibit their growth.

How to Identify Common Problems

If correctly planted in a sunny position, these are pleasingly problem free plants.

As I have already noted birds and squirrels will target the seeds. If you want to protect maturing flowers, and their seeds, cover the plants with a horticultural fleece or net.

When planted and cared for correctly these are incredibly low maintenance, problem free plants. 

If deer are present in your area you will also need to protect your plants from them. Deer like to bite off the heads of young plants.

The only other pest that may show interest is the gray moth. These can lay eggs in the flowers. Regularly inspect your flowers and pick any worms you notice off the plants.

Powdery mildew, rust and downy mildew can all affect the plants. If spotted early these issues can be treated with a general purpose fungicide. Planting in a sunny position, watering correctly and spacing the plants out so that air can circulate freely can all help to prevent these issues.

How to Cut Flowers and Harvest Seeds

Many people grow sunflowers to cut the blooms for indoor displays. If you want to do this try to cut the stem just before the bud opens.

Cut your flowers early in the morning. This helps to prevent wilting. If handled carefully cut flowers last about a week at room temperature. Place the cut blooms in a tall vase to support the heavy head.

Harvesting the Seeds

To harvest the seeds, either to eat, replant or to feed to birds during the winter you must allow the flower to dry on the stem. Leave the flower in place until the back of the head browns and the foliage yellows. At this stage the seeds will look plump and loose.

Use a sharp garden scissors to cut the head off the plant. Make the cut about 6 inches below the flowerhead. You may need to place a container underneath to catch any loose seeds.

Put the cut flower on a flat surface and rub your hand over the seeds to dislodge them. You can also pull them away.

Allow the seeds to dry before cutting the flower head away from the plant and harvesting. 

Rinse the seeds before laying on a flat surface to dry. If you are drying the seeds outside, remember to protect them from birds and other pests.

Once dry, seeds that you wish to sow next year should be stored in an airtight container in a cool dry place.

To roast the seeds, re-soak them in salted water overnight before straining and drying. Spread the rehydrated seeds out in a single layer on a baking sheet. Bake for 25 to 30 minutes at 325 degrees until they are slightly brown.

One of the summer’s most recognizable plants. However big or small your outdoor space, thanks to the variety of plants on offer, anyone can learn how to grow sunflowers. 

One of the most colorful annual flowers, learning how to grow sunflowers is a great way to bring height, drama and structure to your garden. Their bright blooms also add color and attract lots of helpful pollinators to your space. Suitable for both large gardens and small spaces, these are the ideal summer plant.

Bright and cheerfully why not learn how to grow some sunflowers in your garden?