How Long Will It Take for a Helianthus Annuus to Grow?

Stages

• Sunflower seeds sprout in approximately a week and a half. A month later, the flower head appears, and another month later, the flowers bloom. The flowers last about a week. A month after the flowers bloom, the seeds are ripe and ready for harvest.

Varieties

• Varieties of Helianthus annuus require different amounts of time to reach maturity. In most varieties, the seeds ripen in 70 to 110 days.

Climate

• The number of days required for seeds to ripen depends on the growing climate as well as the variety of sunflower. Sunflowers grown in southern states can mature as many as 10 to 15 days earlier than the same variety grown in the northern U.S. or in Canada.

Signs of Maturity

• When the plants are mature, the heads droop toward the ground, tilting the now-yellow back of the flower head upward.The colorful petals around the rim of the flower head turn brown and wither, as do the petals on the tiny flowers on the central disk. In the center of the flower disk, the seeds will appear full and heavy. They are ready for harvest.