Sunflower Guide: Add Some Sunshine to Your Garden

Updated October 5, 2021
Closeup of beautiful sunflower in white bucket at farmers market with blurred sunflowers behind

Sunflowers are some of the most easily recognized and beloved flowers. A wonderful source of not only beautiful blooms, but also food and oil, sunflowers deserve a spot in just about any garden. Though we think of the sunflower as one large flower, each sunflower head is actually made of up dozens to hundreds of tiny flowers, surrounded by a ray of outer petals. Each of those flowers in the center will eventually become a seed!

Growing Sunflowers in Your Garden

Sunflowers (Helianthus annuus) are easy to grow in the right conditions and aren't prone to many pest or disease problems. Plenty of sun, good soil, and regular watering are key to growing amazing sunflowers.

When and How to Plant Sunflowers

Sunflowers are annuals and need warm soil for germination and healthy growth. They really don't like having their roots disturbed, so this is one of those plants that's best sown directly into the garden.

  • Sow sunflower seeds after danger of frost has passed and once the soil has warmed to at least 50 degrees Fahrenheit. In most areas, this will be sometime in April through early July, though in the South, it can be as early as March.
  • You can also sow successions of sunflowers so that you have some coming into bloom just as others are starting to fade. To plan this out, you'll want to know your first fall frost date and look at the Days to Maturity number on the seed packet of the variety you're planting. Count back from your first frost date, and this will tell you the latest date at which you can plant and still get blooms.
  • Sow sunflower seeds about an inch deep and follow the spacing requirements on the seed packet for the variety you're planting.

Where to Plant Sunflower: Light and Soil Requirements

True to their name, sunflowers need full sun to grow well; plant them in a spot that gets at least six hours of sun. Sunflowers are heliotropic, meaning that the flowers will change which direction they face as they follow the sun across the sky. They face east in the morning, straight up at mid-day, and west at sunset. What do sunflowers do overnight? Overnight, they gradually face east again in anticipation of the sunrise. Once the flowers get older, they'll stop moving. They'll stay facing east as they're pollinated, eventually forming the seeds that provide such tasty snacks for both people and wildlife alike.

Keep these soil requirements in mind:

  • As far as soil, they're not overly picky, but sunflowers won't grow well in compacted soil since they form long taproots that can extend up to two feed down into the soil.
  • They're also not picky about soil pH.
  • However, they're heavy feeders, so soil that has plenty of compost or manure, or slow-release fertilizer mixed into it is essential.

Watering and Fertilizing Sunflowers

Keep the soil evenly moist until your sunflowers germinate and then give them at least an inch of water per week once they're a few inches tall. They grow best when they're watered deeply but infrequently; one deep watering per week is all they need. If you water them shallowly, their taproots won't grow as deep as they could, and the plant will be weaker because of it.

The only fertilization sunflowers need is a slow-release fertilizer at planting time, especially if they're planted in soil that's been amended with compost and manure. Then they need another application of compost or manure tea, or fish emulsion, when the flower buds are forming. Fertilizing too frequently will result in weak, floppy stems that will break easily.

Sunflower characteristics

Staking Sunflower Stems

One more thing to keep in mind is that sunflower stems tend to be brittle and the flowers get quite heavy once they've started forming seeds, so if at all possible, try to plant them in a spot that's sheltered from strong winds by a fence or hedge.

Tall varieties of sunflowers should also be supported by staking, especially if they're out in the open and subject to strong winds. As the plants mature and the stems strengthen, they won't need to rely on the stake as much, but early on, it can prevent the stem from snapping.

Pruning or Using Sunflowers as Cut Flowers

If you're growing a multi-branching variety, you can prune off spent blooms when they fade. However, birds and other wildlife will enjoy the seeds, so that's often reason enough to leave spent blooms where they are.

To cut sunflowers for bouquets, cut the stem when the petals just start to open. If you're growing a multi-branching variety, cutting it at this stage will encourage side shoots to form.

It's best to harvest sunflowers either in the morning or evening. If you harvest them during the hotter parts of the day, they'll wilt more and they won't last as long in a vase as they will if you cut them during the cooler part of the day. It's also a good idea to cut the stem at a 45-degree angle, since this allows the flower to take up more water in the vase.

Harvesting Sunflower Seeds

Whether you want the sunflower seeds to snack on, to feed to wildlife, or to save for planting next year, you'll need to harvest them at the right time.

  1. Let the flower stay on the plant until the back of the flower turns from green to brown and the petals fall off. The seeds should be a little loose; check by running a finger across the seeds. If they move or fall out, they're ripe.
  2. Cut the flower head off of the plant.
  3. Over a table, tarp, or sheet, hold the flower head in one hand and run your other hand over the seeds. You can also use a spoon to harvest them; just run the spoon along the seeds, freeing them.
  4. For an even easier method, cut the flower head off and place it in a paper bag, then hang it from a spot in your garage or garden shed. Over time, the seeds will fall out into the bag.
  5. If you're going to eat the seeds, rinse them off, then lay them in a dry spot for a few hours to fully dry before storing.
  6. To save as seed for next year, make sure they're fully dry, then save in a jar or envelope.

Sunflower Pests and Diseases

Far and away, the most intense pest pressure for sunflowers comes from wildlife, such as birds, squirrels, and deer. Birds often eat the seeds right after they've been sown, and once the plant starts forming seeds, they can be tempting for all sorts of wildlife. Consider placing bird netting over the flowers for birds and squirrels. If deer are a problem, they'll need to be planted behind a tall wire fence.

The main disease sunflowers are prone to is powdery mildew, which can affect the leaves. Downy mildew and rust can also occasionally be a problem. At the first sight of these, consider treating your sunflowers with an organic fungicide.

Stunning Sunflowers to Grow in Your Garden

Sunflowers come in all sizes, from mammoth 12-foot-tall varieties all the way down to dwarf varieties that can be grown in containers. You can also find them in a variety of shades from soft creams to vibrant yellows and moody burgundies.

Red Courtesan

Red Courtesan Sunflower

'Red Courtesan' is a deep red, velvety-looking, branching sunflower that grows four to five feet tall, making it an excellent option for a mixed flower border and as a cut flower.

Mammoth Gray Striped

Mammoth Gray Striped Sunflower

These gargantuan, 10 to 12-foot plants bloom in bright yellow and produce seedheads that average 12 inches across, producing tons of seeds.

Teddy Bear

Teddy Bear Sunflower

'Teddy Bear' forms fluffy-looking, bright yellow blooms. They grow three to three and a half feet tall and are a branching variety that also makes for gorgeous cut flowers.

Autumn Beauty

Autumn Beauty Sunflower

This stunning sunflower blooms in shades of yellow, gold, red, rusty orange, and burgundy on seven-foot-tall plants. 'Autumn Beauty' blooms for a long time, so it's a perfect addition to the back of a sunny flower border.

Moulin Rouge

Moulin Rouge Sunflower

If you love red flowers, 'Moulin Rouge' is definitely worth a look. The deep red blooms measure about six inches across. Since 'Moulin Rouge' is a branching variety, it's perfect for both the garden and for cutting.

Vanilla Ice

Vanilla Ice Sunflower

No, this variety is not named after the rapper. The three- to five-inch blooms have a soft, creamy yellow color and bloom prolifically on multi-stemmed plants.

Little Tiger

Little Tiger Sunflower

'Little Tiger' is a dwarf sunflower that only grows one to two feet tall, making it a perfect container option. The petals are rusty orange with yellow tips and warm brown centers, so this is a wonderful plant for fall containers.

Brighten Up Your Garden With Sunflowers

Whether you want to grow enormous blooms with lots of seeds or small varieties for cut flowers, there's definitely a sunflower variety out there for your garden. With lots of sun, rich soil, and a bit of care, you'll be well on your way to having plenty of cheerful blooms.

Sunflower Guide: Add Some Sunshine to Your Garden