Description

Growing Guidelines for Sunflowers

Sunflowers thrive when grown directly from seeds planted in the garden after the last frost.

• Directly sow seeds in average soil under full sun once all frost danger has passed.
• When selecting a site, ensure sunflowers have well-drained soil and are placed in an open area of the garden where they face the sun. Plant taller varieties at the north end to avoid shading other plants.
• Prepare the soil by removing weeds and incorporating organic matter into the top 6-8 inches, then level it.
• Most plants benefit from organic matter like compost, which enriches soil with nutrients and maintains ideal pH levels. Add compost at any time or top-dress the soil with 1-2 inches of organic mulch after planting to promote breakdown into compost. Conduct a soil test after the growing season to determine necessary amendments for the next year.
• Sow seeds ½ inch deep in groups of 2 or 3 seeds, spacing groups 18-24 inches apart based on variety.
• Lightly firm the soil, water thoroughly, and maintain even moisture.
• Seedlings typically emerge in 7-10 days. Thin to one plant per group when seedlings have two sets of leaves.
• Manage weeds throughout the growing season to prevent competition for water, space, and nutrients. Cultivate or use mulch to suppress weed growth.
• Mulches retain soil moisture and regulate soil temperature. For annuals, shredded leaf mulch provides a natural look and improves soil over time. Ensure mulch does not touch plant stems to prevent potential rot.
• Keep soil evenly moist but not saturated.
• Established sunflowers can withstand drought conditions.
• Fertilization is unnecessary unless soil quality is poor; avoid excessive fertilization.
• Monitor for pests and diseases. Consult your local Cooperative Extension Service for region-specific pest control recommendations.
• Some varieties produce a single bloom; remove plants after blooming to prevent disease the following year.
• Remove plants after frost kills them in fall to prevent disease issues in subsequent seasons.
• Edible sunflowers mature approximately 3 months after sowing. Harvest seeds by cutting heads after stalks dry but before fall or winter rains. Check for maturity by observing florets in the center of the flower disk, which should shrivel and turn yellow. Cut flower heads with a foot of stalk attached, then dry seeds in a warm, dry, ventilated place. Protect seeds with cheesecloth, netting, or a paper bag with ventilation holes to collect any that may drop during drying.
• Shorter varieties can be successfully grown in containers using commercial potting mix.
• Pollenless varieties are excellent choices for cut flower arrangements.