How to Grow and Care for Ice Cube Dahlia

The Ice Cube dahlia is an anemone or collarette type, featuring a central cushion of tubular petals surrounded by a single row of flat, white outer petals. Its pure white coloration makes it a popular choice for gardens and floral arrangements. This variety grows to a height of 36 to 48 inches and produces blooms from mid-summer until the first frost.

Planting and Site Selection

Dahlia tubers should be planted in the spring after all danger of frost has passed and the soil has warmed to at least 60°F. Select a site that receives a minimum of six to eight hours of direct sunlight. In regions with extreme summer heat, providing some shade during the hottest part of the afternoon can be beneficial.

Dahlias thrive in well-draining, fertile soil. Before planting, amend the garden bed with two to three inches of compost or well-rotted manure. Loosening the soil to a depth of about 12 inches will also improve root development.

Dig a hole four to six inches deep and place the tuber horizontally with the “eye,” or growing point, facing upward. Cover it with a few inches of soil, but do not water immediately unless the soil is exceptionally dry, as excess moisture can cause rot. Space tubers approximately 12 to 18 inches apart to allow for adequate growth and air circulation.

Essential Care and Maintenance

Once green shoots emerge, begin a regular watering schedule. Dahlias perform best with deep, infrequent watering, which encourages strong root growth. Allow the soil to dry out slightly between waterings to keep it evenly moist but not waterlogged, preventing tuber rot.

To promote plentiful flowers instead of excessive foliage, use a low-nitrogen fertilizer. A formulation with higher potassium and phosphorus, such as a 5-10-10 or 10-20-20 ratio, is suitable. Begin fertilizing when plants are eight inches tall and continue every four to six weeks during the growing season.

Taller dahlia varieties need support to prevent stems from breaking. Insert a stake at the time of planting to avoid damaging the tuber. As the plant grows, loosely tie the main stems to the stake with soft twine.

To encourage a bushier plant with more flowers, pinch or cut the top three to four inches of the central stem when the plant is 12 to 16 inches tall. Regularly deadheading, or removing spent flowers, will also direct the plant’s energy into producing new blooms.

Overwintering Tubers

In climates where the ground freezes, tubers must be lifted and stored for winter. After the first hard frost kills the foliage but before the ground freezes, cut the stems down to about four inches. This timing allows the tuber to enter dormancy, which improves storage success.

Use a garden fork to loosen the soil in a circle about one foot away from the stem to avoid damaging the tubers. Gently lift the clump from the ground and brush off excess soil, but do not wash them. Allow the tuber clump to dry for a few days in a cool, dark location.

Store tubers in a cool, dark environment with some humidity and temperatures between 40-50°F, such as a basement or unheated garage. Place the dry tubers in a box and cover them with peat moss, sand, or wood shavings to prevent them from drying out. Periodically check the tubers during winter and discard any that show signs of rot.

Common Pests and Diseases

Slugs and snails are fond of new growth and can be managed with organic repellents or by keeping the soil surface dry. Aphids and spider mites are sap-sucking insects that cause leaves to yellow and distort, with spider mites being more common in hot, dry weather. Removing garden debris can help deter pests like earwigs.

The most common disease is powdery mildew, which appears as a white coating on the leaves. Prevent this fungal disease by ensuring good air circulation through proper spacing and trimming lower leaves. Watering the soil directly instead of the foliage also keeps leaves dry and less susceptible to fungal issues.