Dahlia

If you have ever been to a state fair, you have probably seen a pavilion filled with exotic and amazing dahlia blossoms. These hugely varietal flowers are a collector’s dream, with little starburst blooms to plate-sized flowers in every hue imaginable. Dahlias are relatively sturdy plants if grown in the right lighting, heat, and soil. Care of dahlia flowers may vary dependent upon your zone, but here are a few dahlia growing tips to help you get maximum blooms and healthy, bushy plants.

How to Grow a Dahlia Plant
Dahlias are classified according to flower shape and petal arrangement. The plants are borne from tubers, which require well-drained soil and plenty of sunlight. Caring for dahlia plants starts at installation with the cultivation of the soil and healthy tubers. Learning how to grow a dahlia plant will likely lead to a hobby, as the spectacular blooms are quite addictive and the presence of one or two will lead to plenty more in subsequent seasons.

Select healthy tubers of a variety that does well in your zone. The outside of the tuber should be firm with no mold or rotten spots. Prepare the garden bed. These plants prefer well-drained, acidic loam but will grow relatively well in any soil as long as it isn’t soggy.

Dig down 8 to 12 inches and add compost to increase the porosity and nutrient density since dahlias are big feeders.  Here in the Carondelet Garden we add a bit of fish, blood and bone meal to each planting hold and water in.  Small plants can be spaced 12 inches apart, but the big dahlias need to be planted 3 feet part to accommodate the large bushes. Lay the tuber sprout-side up 3 inches deep in a trench and cover it over with the prepared soil.

Dahlia Care
Dahlias need to be kept weed-free. Use organic mulch around the plants to prevent weeds and conserve moisture.  Pinch back the terminal buds when the plant is 15 inches (38 cm.) tall to enforce good branching and structure and increase budding.

Provide plenty of water to your plants. Water plants deeply once or twice per week. Big dahlias need a support structure to keep the heavy blooms from bending to the ground. Fertilize monthly with a water-soluble fertilizer or twice during the growing season use ½ cup (120 mL.) 5-10-10 scattered around the root zone of the plants. Good dahlia care also includes pest management.

Caring for Dahlia Plants in Winter
Cut down dahlias about two weeks after the first hard frost, then gently lift the tubers and tip them upside down to get the moisture out of the stalks.  Overwinter tubers covered with spent compost in cardboard boxes and place in a frost-free cool environment.

​Wait to divide any large tubers that may need splitting until late March- bigger clumps overwinter better when they are left intact.