The Best Season to Sow Sunflower Seeds

Temperatures

• Many varieties of sunflowers are tolerant to the cold and can withstand low temperatures, with seeds germinating at soil temperatures as low as 39 degrees Fahrenheit. However, the U.S. Department of Agriculture recommends waiting until soil temperatures reach 45 degrees Fahrenheit in the spring.

Time Frame

• Soil temperatures heat up more quickly in southern areas, so planting times may be weeks to a full month later there than in northern areas. For example, May is the ideal month to sow sunflower seeds in Canada, while parts of the southern United States may start planting as early as mid-March and early-April. Sowing should cease after June, unless sowing dwarf varieties.

Considerations

• Sunflowers take a while to develop from seed into seed-bearing heads, so you may want to consider the final frost date of the year when choosing when to sow seeds. Blooming alone takes 55 to 75 days following planting, while it takes approximately 100 days for sunflowers to reach full maturity after sowing.