Sunflowers

With bright blooms that go all summer, sunflowers are heat-tolerant, resistant to pests, and attractive to pollinators. They make beautiful cut flowers and their seeds are a source of food for birds and people! Learn how to plant, grow, and harvest sunflowers.

About Sunflowers

The sunflower (Helianthus annuus) is an annual plant with a large daisy-like flower face. Its scientific name comes from the Greek words helios (“sun”) and anthos (“flower”). The flowers come in many colors (yellow, red, orange, maroon, brown), but they are commonly bright yellow with brown centers that ripen into heavy heads filled with seeds.

Sunflowers are heliotropic, which means that they turn their flowers to follow the movement of the Sun across the sky east to west, and then returns at night to face the east, ready again for the morning sun. Heliotropism happens during the earlier stages before the flower grows heavy with seeds.

There are tons of varieties of sunflowers available today, so there’s bound to be one that fits your garden. Choose between those with branching stems or single stems, those that produce ample pollen for pollinators or are pollen-free (best for bouquets), those that stay small or tower above the rest of the garden, or those that produce edible seeds! Learn more about why you should start growing these happy flowers in your garden.

Here and yonder, high and low,

Goldenrod and sunflowers glow.

–Robert Kelley Weeks (1840–76)

How Long Do Sunflowers Take to Bloom?

A fairly fast-growing flower for their size, most sunflower varieties mature in only 80 to 95 days. The largest sunflower varieties grow to over 16 feet in height, while smaller varieties have been developed for small spaces and containers and rarely grow larger than a foot tall! The flower heads can reach over 12 inches in diameter within the large seeded varieties.

First and foremost, find a sunny spot! Sunflowers grow best in locations with direct sunlight (6 to 8 hours per day); they require long, warm summers to flower well.

Choose a location with well-draining soil. The planting spot shouldn’t pool with water after it rains. Otherwise, sunflowers aren’t too picky about soil, but for the best results, it shouldn’t be too compacted. They have long tap roots that need to stretch out; in preparing a bed, dig down 2 feet in depth and about 3 feet across.They’re not too fussy when it comes to soil pH either. Sunflowers thrive in slightly acidic to somewhat alkaline soil (pH 6.0 to 7.5).

Sunflowers are heavy feeders, however, so the soil needs to be nutrient-rich with organic matter or composted (aged) manure. Or, work in a slow release granular fertilizer 8 inches deep into your soil.

If possible, plant sunflowers in a spot that is sheltered from strong winds, perhaps along a fence or near a building. Larger varieties may become top-heavy and a strong wind can be devastating.

Before choosing a planting site, decide whether or not you want to grow a sunflower tower—a fun project for kids!

When to Plant Sunflowers

It’s best to sow sunflower seeds directly into the garden (or outdoor containers) after the danger of spring frost has passed anytime after soils have warmed to at least 50°F (10°C).

In the northern half of the U.S. and in Canada, this will fall between April and mid-June. In the South, this will probably occur in mid-March or early April.

Sunflowers dislike having their roots disturbed, which is why we recommend direct-sowing instead of transplanting.

Planting Sunflower Seeds

Sunflowers should be planted 1 to 1½ inches deep and about 6 inches apart after the soil has thoroughly warmed. If you wish, you can plant multiple seeds and thin them to the strongest contenders when the plants are six inches tall.

Give plants plenty of room, especially for low-growing varieties that will branch out. Make rows about 30 inches apart. (For very small varieties, plant closer together.)

A light application of fertilizer mixed in at planting time will encourage strong root growth to protect them from blowing over in the wind.

Experiment with plantings staggered over 5 to 6 weeks to keep enjoying continuous blooms.

If you see birds scratching around for the seeds, spread netting over the planted area until seeds germinate. See more ways to keep birds away from your garden.