Start indoors 4 weeks before last frost for the earliest sunflowers in your garden and to market. Direct sow 1 to 2 weeks after last frost. We let the birds take the first seeds before we harvest our sunflower seeds. This will also help volunteer them around your garden over the years. Tall plants may need support. Plant out directly after last frost. Growing repeatedly in the same location, sunflowers have an allopathic affect deterring the growth of several mustards and other weeds with a herbicide from their roots. Soil pH 4.5-8.7. Hardiness zones 7. Annual.
Days from maturity calculated from the date of seeding. Average between 560-1,120 seeds per ounce. Federal germination standard: 75%. Usual seed life 7 years. Isolation distance for seed saving: 1/2 mile.
Planting Depth 1”
Soil Temp. Germ. 60-70˚F
Days to Germ. 5-10
Plant Spacing 2’
Row Spacing 2-3’
Days To Maturity 100-110Full Sun
, Moist Well Drained