How to Sow & Grow Sunflowers For A Summer Of Cheerful Blooms

Sunflowers are one of the most captivating flowers in a garden. Some gardeners grow rows of them for photo backgrounds, while others want to draw in bees and pollinators all summer. Sunflowers also make beautiful cut flowers to enjoy inside on a long summer day.

If these qualities appeal to you, let this be the year you grow sunflowers in your garden.

Sunflowers can easily be grown in containers, raised garden beds, or a field if you are lucky enough to have one at your disposal. They are low-maintenance plants that just about anyone can grow.

Here are the best tips on how to sow and grow sunflowers, so you can enjoy their beauty all summer long.

Common name	Sunflower
Botanical name	Helianthus annuus
Growth habit	Single stem or branching, dwarf to mammoth
When to start seeds	Spring, 2-4 weeks before danger of last frost
When to transplant/direct sow	After risk of last frost
Mature plant height	2-14 feet
Sunlight requirements	Full sun
Water requirements	Regular water, 1″ per week
Soil requirements	Most soil types, well-draining
Blooming period	Summer to fall, 50-120 days to maturity
Appearance	single or double blooms, orange, red, burgundy, pale yellow, golden yellow
Pests & Diseases	aphids, thrips, rust

Choosing Sunflower Seed Varieties

You are probably most familiar with yellow sunflowers with a brown center. But did you know that there are over 70 different varieties of sunflowers?

The diversity of sunflower blooms includes differences in:

• Height: dwarf to mammoth, 2-14 feet tall
• Color: golden yellow, pale yellow, burgundy, and more
• Growing habit: single stem or branching
• Bears pollen or pollenless
• Bloom size: diminutive 3-inch blooms to foot-wide flower heads

Branching Varieties

The branching types of sunflower produce more blooms per stem than single-stem varieties. One central stem creates a multitude of lateral branches, each of which develops a flower bud.

Branching varieties tend to create pollen, making them less suited as cut flowers but excellent at attracting pollinators and beautifying the garden for weeks.

Single Stem Varieties

Single stem varieties of sunflowers produce a single flower per stem. Once the bloom dies or is cut, the plant will not produce any more flowers, making succession sowing an essential tool to have continuous blooms.

This type of sunflower makes an excellent cut flower and is favored among florists. Single stem sunflowers are generally pollenless, which results in longer-lasting cut flowers. The stems are also longer, making them easier to use in flower arrangements.

Giant sunflowers are technically single stem, but they’re certainly not the sunflower variety you want to grow for cutting. Good luck finding a vase to fit that stem!

Easily start sunflowers from seed

Sunflowers are very simple plants to start growing. They can be planted directly into the ground in flower beds or raised garden beds. The small varieties can even be planted in containers where they will attract pollinators right to your porch or patio.

Tall sunflowers should be planted near a fence or some kind of barrier that protects them from the wind. These plants are top-heavy and can easily be blown over.

Direct Sowing

Sunflowers appreciate being direct sown into the garden, as they can be finicky about being handled once they sprout.

Single stem sunflower seeds can be sown 6 inches apart, whereas branching sunflowers will need at least a food between plants. Both types of seeds should be planted one inch deep, covered with soil, and kept moist until germination.

Wherever you plant your seeds, make sure the seedlings will get full sun right from the start to develop strong stems that can support the weight of the mature plant and flower head.

Starting seeds indoors for transplanting

Even though sunflowers are very easy to direct sow, starting the seeds inside can be a great option for gardeners in shorter growing seasons or if you want to have more precise planting.

As long as you transplant the sunflower seedlings when they are still small, they will adapt to their new environment and take off with quick growth.

Fill a seed tray or small pots with seed-starting mix and plant 1-2 sunflower seeds per cell. Cover the seeds with one inch of the mix and water them well. Place the trays in a warm and sunny area to germinate.

It can take 7-14 days for the seeds to germinate. If both seeds germinate, the weaker one should be removed, but not until the stronger one has produced a second set of leaves.

After the danger of frost has passed the seedlings can be transplanted outdoors. Don’t forget to harden them off in a sheltered spot to acclimate them to the outside temperatures and sun.

For a more in-depth guide to starting flower seeds, bookmark this resource: Step-By-Step Guide To Starting Seeds Indoors (Plus a sample setup).

How Long Do Sunflowers Take to Bloom?

Sunflowers take 50-120 days from seed to bloom. Single stem sunflowers are the quickest at 50-60 days, and branching sunflowers take 100-120 days. The larger growth of branching sunflowers accounts for a longer time to bloom.

Once your sunflowers start blooming, you can enjoy each flower for a couple of weeks. If you keep the plants deadheaded, you’ll get even more blooms from your branching sunflowers.

Learn how to deadhead sunflowers in this article: How to Deadhead Sunflowers (Quick Chore For More Flowers).

When to Plant Sunflowers

Before you plant anything in the garden, make sure you know the general dates for your growing season. Sunflowers are sun-loving plants and therefore grow the best during the summer months the temperatures are high and the days are long.

Know Your Last Frost Date

Your sunflower seeds can be planted in the spring once the risk of frost is gone. The Farmer’s Almanac can help you look up this date using your zip code. It will also tell you how many days your growing season is so you know how many rounds of sunflowers you can fit in.

The soil should be 60°F when you plant the seeds. For most gardeners, this will fall somewhere between April and May, but to get a more specific date, use the resource above and plan your plantings with it.

How Late Can You Plant Sunflowers?

Many gardeners will recommend planting seeds over a couple of weeks. This can give you continuous blooms throughout the season. But how late into the growing season can you plant sunflowers?

You should look at the seed’s packet and find out how long it takes that specific variety to bloom. Then you want to look up your first frost date. If your variety takes 80 days to bloom you want to make sure the last seed is planted at least 80 days before your first frost date.

You should also know that the later in the season you plant your seeds the shorter they will grow, and the fewer blooms they will produce. This occurs because there is less sunlight present later in the season.

For even more details, jump over to this article, How Late Can You Plant Sunflowers? Check Your Zone & Date Here.

Sunflower Growing Tips

Soil ph	6.0-7.5
Type of soil	average, well-draining
Sunlight	full sun
Water	1-2 times/week
Fertilizer	beginning and midseason, compost or organic fertilizer

Soil 

Sunflowers are low-maintenance plants, and they will thrive in many soil types, though they prefer loose and well-draining soil. They are heavy feeders and need soil that is rich in nutrients. Adding in compost or worm castings at the start of the season is a great way to set your sunflowers up for the season.

Sunlight

Sunflowers love sunlight. They thrive in 6-8 hours of sunlight a day, but they can handle even more. They will grow better and faster if they have ample access to sunlight.

If you only have a partially sunny area to grow your flowers, stick to dwarf or shorter varieties instead of the mammoth ones for a better chance of strong stalks and big blooms.

Water

As with any plant in your garden, sunflowers need regular water throughout the week, especially when they are young and don’t yet have an extensive root system.

I tend to water my sunflowers every few days during the summer with a half to full gallon of water each time. I do this via a drip irrigation system, but you can easily hand-water at the base of the plant, too.

Fertilizer

Many gardeners recommend using an organic, slow-release fertilizer when you plant your sunflower seeds. A slow-releasing fertilizer helps the plant grow at a uniform rate and encourages a strong root system to form.

You can also opt for mixing compost or worm castings into the soil before planting, and that will provide the same benefits.

I like to side-dress my sunflowers with a little compost every few weeks during the growing season, too, especially if I’m succession sowing single stem sunflowers. That way each new batch of plants will get fresh nutrients to help them grow and a little extra organic matter adds to overall soil health.

Common Pests and Diseases

Sunflowers are a great feeding source for countless pests. Luckily sunflowers are resilient plants that withstand some pest pressure.

When it comes down to it, sunflowers are fast growers, so even if they succumb to pests or diseases, it’s easy enough to plant another round of seeds to replace any that you lose.

Aphids: These soft-bodied pests will congregate on the underside of leaves and stems. You can blast them away with a strong stream of water from the hose, or you can use insecticidal soap to get rid of them.

Caterpillars: These voracious eaters will quickly destroy your sunflower crop if you don’t keep an eye out for them. Hand-pick them off of plants and drop them into a bucket of soapy water to kill them.

Japanese Beetles: These pests are particularly fond of sunflowers. You can hand-pick them off of your plants and drop them into a bucket of soapy water, or you can use an insecticide designed to kill Japanese beetles.

Rust: This fungal disease will cause yellow spots to form on leaves, and eventually the leaves will turn brown and die. Rust is most common in humid conditions. The best way to prevent rust is to keep the plant leaves dry by watering at the base of the plant.

One of the most common organic ways to remove pests from sunflower plants is to create a soapy water solution. Mix 4-6 tablespoons of soap into a gallon of water. Spray the top and underside of the leaves to coat the insects, repeating daily until the infestation is gone.

Be sure to spray underneath the leaves as well. Some pests will hide on the underside and will not be deterred unless they are sprayed with homemade insecticide.

If you see only a few bugs, it’s probably not work spraying anything. More than likely, once the flowers start blooming, birds and beneficial insects will be attracted to your garden and will help patrol the plants for pests.

Cutting Sunflowers for Bouquets

Sunflowers make an excellent focal flower in any bouquet or arrangement. They are long-lasting when cut and make a statement whether they are used alone or in a mixed bouquet.

Single stem sunflowers are the most common to grow for bouquets, but branching sunflowers will work, too. They might not last as long, and they often have messy pollen, but the color variations of branching sunflowers are hard to beat.

If you need some inspiration of which varieties to grow, learn about some of the most common ones in this article: The Best Sunflowers For Cutting (Grown By Flower Farmers).

The best time to cut sunflowers for bouquets is when the flowers are just beginning to open. You can tell they are ready when the petals start to pull away from the center of the flower.

Harvest your sunflowers first thing in the morning when they’re fresh. Cutting the blooms in the heat of the day can cause the blooms to prematurely wilt. 

Use a sharp knife or scissors to cut the stem at a 45-degree angle. This angle gives the plant a bigger surface area to absorb water. Once cut, immediately put the stem in a jar or bucket of water until you’re ready to transfer them to a vase.

Save Sunflower Seeds for Next Year

Sunflowers produce a lot of seeds that you can harvest for next year’s crop, or save to provide a winter food source for birds. But before you start collecting seeds, there are a few things you should know.

Not all sunflowers will produce viable seeds. If you want to save seeds from your sunflowers, make sure to grow only open-pollinated varieties. These varieties will produce true-to-type plants that will be identical to the parent plant.

If you grow hybrid sunflowers, the plants that result from saving the seeds will be very different from the parent plant.

To collect seeds, wait until the back of the flower head turns brown and starts to dry out. This usually happens in late summer or early fall.

Cut the flower heads off of the plant and put them in a paper bag to dry for a few weeks. Once they’re completely dried out, rub the seed heads between your hands to release the seeds.

Sift through the resulting seed chaff (the bits of leaves, stems, and petals) to remove any debris. Store the seeds in a cool, dry place until you’re ready to plant them next spring.

For other ideas on what to do with your sunflowers once they’re past their prime, check out this article: 7 Ways To Repurpose Dead Sunflowers (Seeds, Stalks, and More).

FAQ

Do Sunflowers Need to Be Staked?

Some varieties of sunflower seeds do not need to be staked. However, if the variety grows over three feet tall then the plant should be staked for support.

Sunflowers are very top-heavy and can be knocked over by wind and rain. The branching varieties also have brittle stems and will require some outside support. Loosely tie the plant to the stake as needed throughout the growing season.

Can Sunflowers Be Grown in Containers?

Dwarf sunflower varieties can be grown in containers. One dwarf sunflower can be planted in a 6-inch container or three can be planted in a one-gallon container.

Dwarf variety sunflowers will not grow as large in pots as they do when planted in a raised garden bed or directly into the ground, but they will still produce beautiful blooms.

Do Sunflowers Need Full Sun?

Sunflowers are considered full sun plants. They need anywhere from 6-8 hours of sun a day. The more sun a sunflower receives the stronger it will grow.

As the day goes on, you’ll notice that these are heliotropic plants, which means they follow the path of the sun. You will see them facing east in the morning and by the evening they will be facing west as the sun sets.