How to Care for a Dahlia Flower

Harvesting of dahlia flowers right after they open encourages continued blooming.

Dahlias are perennials that grow for many years from one foundation of tuberous roots. They reach 1 to 6 feet in height, depending on variety, and bloom in a range of colors from spring to summer. To achieve significant size and fullness of bloom, however, dahlias require the right planting time, location and soil. They also need the right maintenance after they begin to grow. Wait until all danger of frost has passed before planting the bright bushes in your garden.

Things You'll Need

• Organic compost
• Garden fork
• Fertilizer
• Mulch
• Stake/trellis
• Cords

Instructions

1. Plant dahlias after the average last frost date for your region. Choose a site that gets at least six hours of sun every day, drains quickly and offers 2 feet of space per plant.

2. Dig into the top 10 inches of soil in a foot-wide area to loosen it, then mix 4 inches of organic compost, peat moss, pine bark or rotted manure into the soil to add drainage and nutrition. Add 8-8-8, 10-10-10, 5-10-15 or 5-10-10 fertilizer to the entire 10 inches of tilled soil.

3. Plant dahlia seeds 1/2 inch deep---or tubers 3 inches deep---every 2 feet. Cover the planting with soil until you have an even surface, then water each site with 2 to 3 inches of water. Put the dahlias on a weekly schedule of the same amount of water.

4. Spread 2 inches of organic mulch, such as straw, wood shavings or pine bark, over the soil around each planting to help keep the soil warm and moist and restrict weed growth.

5. Weed the dahlia patch regularly. Dahlias can't grow with competition from other grasses or weeds.

6. Trellis or stake the dahlias when they get tall enough. Put a structure 1 foot behind the plant and use soft cord ties to secure the plant's main stems to the structure.

7. Pinch off the first flower bud on each plant to encourage more vegetative growth. Allow the next set of flower buds to grow, but pinch off any secondary buds that grow on branches with set flowers, so that each stem supports only one bloom. Pinch off suckers at both stem and leaf junctions to help the plants maintain their energy for healthy growth and blooming.

8. Feed dahlias again when they are 1 foot tall with 5-10-5 or 5-10-10 granular fertilizer. Spread the fertilizer in a 2-foot circle around each plant, then water the fertilizer into the ground. Feed dahlias in spring before the first growth emerges.

References

• University of Minnesota Extension; Growing Dahlias, Paul E. Read
• Ohio State University Extension Fact Sheet; Growing Dahlias, Jack Kerrigan
• North Carolina State University; Dahlias for the Home Landscape, Erv Evans