When to Plant Dahlia Seeds
Sow in flats or trays indoors, 4-5 weeks before the final frost date of the Spring. Transplant outdoors after the threat of frost, when soil temperatures are consistently 65-70°F.
Where to Plant Dahlia Seeds
Choose a Full Sun location with well-draining, low nitrogen soil.
How to Plant Dahlia Seeds
Dahlia seeds require light to germinate, so be careful not to cover them when planting. Learn more about germination light requirements here.
Start indoors with plain potting soil, avoiding soils amended with fertilizers. Sow your seeds onto the surface of the soil and compress, but don't cover, as they require light exposure to germinate. Transplant in 4-5 weeks outdoors. Once established, fertilize with a high-phosphorus fertilizer after about 3 weeks.
How to Care for Dahlias
You can continue to fertilize with a high-phosphorus fertilizer approximately every 3-4 weeks to encourage blooms. Over fertilizing will lead to bushy growth with smaller blooms. In the Fall, after the plants have died back, cut your growth down to about 2 inches above the surface of the soil. Carefully dig out your dahlia tubers that have developed and remove any excess soil. Dry for 1-3 days, and store in cool, dry conditions with little exposure to sunlight. Your Dahlia tubers can be planted once again the following Spring.