When Is the Right Time to Plant Sunflowers?

sunflower closeup in garden with green buds and red flowers in background

Jacky Parker Photography/Getty

Sunflowers (Helianthus annuus) are annuals, meaning they must be planted early to late spring, depending on the temperature in your growing zone. You'll know when to plant sunflowers once the soil temperature reaches at least 60 degrees Fahrenheit and all danger of frost has passed.

Some sunflower varieties germinate at soil temperatures between 70 and 85 degrees Fahrenheit, but seeds can be planted when the soil hits 60 degrees. You can check soil temperature by sticking an instant-read thermometer in the soil or by consulting your local cooperative extension office.

When Should Sunflowers Be Planted?

Plant sunflowers around three weeks after the last frost date for your growing zone. Wait until the soil temperature is at least 60 degrees to direct seed sunflowers. In the southern United States, this can happen as soon as early March, or as late as mid-June in regions like New England or the Upper Midwest.

How to Plant Sunflower Seeds

With their large seeds, sunflowers are easy to direct sow. You can also start them indoors a few weeks before your region's last frost date in peat pots or other biodegradable containers, then transplant seedlings once the soil has warmed.

  1. Choose a spot with slightly acidic, well-drained soil and full sun to plant sunflowers. Work organic compost into the soil a few weeks before you plan to plant.
  2. Check the seed packet for the spacing and mature size of the sunflower variety you chose to determine spacing. In general, sunflowers under five feet tall should be planted at least six inches apart, with taller varieties 12 to 15 inches apart. Plant giant sunflower varieties, which can grow up to 15 feet in height, at least two feet apart. Space rows at least two feet apart.
  3. Direct sow sunflower seeds one to two inches deep. Plant seeds deeper in sandier soil.
  4. Water sunflower seeds regularly for the first week or so to support good germination, which typically takes one to 14 days. After that, make sure your sunflowers get at least an inch of water per week throughout the season.
  5. Plant additional successions of sunflowers every week or two to enjoy blooms later in the summer.

Top Varieties to Grow

The best variety of sunflower to grow depends on how much space you want to devote to the plants in your garden. Dwarf varieties, which grow shorter than three feet, are ideal for small spaces, container planting, and borders. Semi-dwarf varieties grow to between three and eight feet tall, while giant sunflowers grow at least eight feet tall.

Another consideration is color. While the classic sunflower has a brown center surrounded by rich yellow petals, they're also available in shades of red, yellow, orange, white, pink, and brown. Here are some of the top sunflower varieties to plant in your garden.

  • Teddy Bear: This compact dwarf variety with double orange petals and a tiny green center is a great option if you don't have much room for sunflowers.
  • Elf: Thought to be the shortest sunflower available, this pint-sized variety maxes out at 16 inches tall, making them perfect for cheering up a window box or other small planter.
  • Chocolate: Named for its deep reddish-brown petals and dark brown centers, this semi-dwarf variety adds contrast to brighter colors while hitting four to five feet tall at maturity.
  • Italian White: These semi-dwarf sunflowers are known for their pale, cream-colored petals, which pop against small, deep-brown seed heads. They'll grow to between four and six feet, making them a versatile option for flower gardens and backyards.
  • American Giant: With heights of up to 14 feet, this stunning giant variety is one of the tallest out there. Its massive flower heads measure up to one foot across.
  • Russian Mammoth: With its huge, golden-hued flowers and 12-foot height at maturity, this giant sunflower is excellent for creating a colorful privacy screen.
  • What is the best month to plant sunflowers?

    The best month to plant sunflowers depends on your climate and growing zone. In the northern United States, sunflowers can be planted in the spring as early as April and as late as mid-June. In the southern U.S., sow sunflowers in March or April.

  • Do sunflowers grow back every year?

    Some sunflowers are annuals and must be replanted each year. However, these types can reseed themselves easily, so you may not need to replant annual sunflower varieties. Perennial sunflower species will grow back each year once they are established.

  • How late can I plant sunflower seeds?

    This depends on your region's hardiness zone. In the warmest regions, sunflowers can be planted as late as August. In cold, northern climates, you can plant fast-growing varieties as late as July for a harvest before the first frost hits in early fall.

Article Sources
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  1. Growing Sunflowers in the Home Garden. University of Georgia Extension.