Germination Requirements for Sunflowers

Site Conditions

• Sunflowers germinate and grow best in soils that are well drained with high nutrient values. A minimum of six hours of direct sunlight is required. Sunflowers receiving less than six hours of direct sunlight per day are spindly and cannot support the weight of their own flowerheads. While germinating, sunflowers should receive about an inch of water per week.

Planting Requirements

• The rate and depth of seeding sunflowers depends upon the variety being planted. Recommended rates are between 3 and 4 lbs. of seed per acre. The seeds should be sown to a depth of 1 to 1-1/2 inches. The space between rows should be wide enough for cultivation. This usually means spacing between 20 and 30 inches between rows. Plant sunflowers in late spring after the threat of frost has passed.

Cultivation

• Practice crop rotation if sunflowers are planted in successive years. Diseases that harm sunflowers remain in the soil for years. If rotation options are limited due to space, select disease-resistant varieties. If growing sunflowers fir their seed, do not cut off the heads to dry until the green discs on the back of the flowerhead start to turn yellow. At that point, cut the heads with about 1 foot of stem attached and hang them to dry.

Other Considerations

• Birds are a nuisance to sunflower growers. Protect sunflower heads from birds by covering with a mesh type fabric. Insect pests, such as sunflower head moths, aphids and whiteflies, sometimes infest sunflowers. Choose an appropriate insecticide based on whether they are being grown for aesthetics or consumption. Overly moist conditions and continual contact with water on the foliage may cause fungal problems. Use the same precautions with fungicide selection and application as with insecticides.