How to Grow and Care for Santa Claus Dahlia

The Santa Claus dahlia is a large-flowered variety known for its bicolored petals. The blooms are a mix of red and white that resemble a pinwheel and can grow up to 10 inches in diameter, earning the “dinnerplate” classification. This variety reaches a height of 36 to 48 inches and provides flowers from mid-summer until the first frost. Its appearance makes it a popular choice for garden borders and as a cut flower.

Planting Santa Claus Dahlias

Proper timing and location are important for planting Santa Claus dahlias. The tubers are sensitive to cold and should be planted in the spring after all danger of frost has passed. For the best growth, select a site that receives at least six to eight hours of direct sunlight each day. The soil should be porous and well-draining to prevent the tubers from rotting.

Before planting, prepare the garden bed. If you have heavy clay or sandy soil, amend it with a three to four-inch layer of organic matter like compost or peat moss. This improves both drainage and water retention. Plant the tubers horizontally 4 to 6 inches deep, spaced 18 to 24 inches apart. Position the tuber so the “eye,” or the small sprout from which the stalk will grow, is facing upwards. Do not water the tubers immediately after planting; wait until the first green shoots emerge from the soil to prevent rot.

Ongoing Care and Support

Once your dahlias are actively growing, they require consistent moisture to support their foliage and large blooms. Water them deeply once or twice a week, ensuring the soil is soaked thoroughly. This encourages the root system to grow deeper. During the hottest parts of summer, their water needs will increase, especially once the plants are large and flowering.

To promote more flowers rather than excessive leaf growth, use a fertilizer that is low in nitrogen. Begin applying a high-potash fertilizer about a month after planting. Continue to feed the plants every three to four weeks throughout the growing season until early fall.

The weight of the dinnerplate-sized flowers makes the stems susceptible to bending and breaking, so providing support is necessary. The most effective method is to insert a sturdy stake, at least five to six feet tall, into the ground next to the tuber at planting time. Doing so avoids the risk of piercing the tuber system later on. As the main stalk grows, loosely tie it to the stake at one-foot intervals to keep it secure.

End-of-Season Dahlia Care

To ensure a long blooming period, deadhead the plant regularly. This involves snipping off the spent flowers just above a set of leaves. Removing old blooms encourages the plant to create new flowers instead of expending energy on seed production, keeping your garden colorful into the fall.

In colder climates (USDA zones 7 and below), dahlia tubers must be lifted for storage. After the first hard frost has blackened the foliage, cut the stalks down to four to six inches. Carefully dig around the plant to lift the entire tuber clump without damage. Allow the clump to air dry for a few days in a sheltered location, then brush off the excess soil and store the tubers in a box with a medium like peat moss or wood shavings. Keep them in a cool, dark, and frost-free place until spring.

Common Issues and Solutions

Slugs and earwigs can chew on the leaves and petals, but they can be managed with simple traps. Spider mites can become an issue in hot, dry weather; spraying the foliage with insecticidal soap can help control them. Thrips may also appear in hot conditions and can be managed with occasional spraying.

Powdery mildew is a fungal disease that appears as a white, dusty coating on leaves, often a result of high humidity and poor air circulation. To prevent it, ensure your dahlias have adequate spacing to allow air to move freely. If mildew does appear, a fungicide can be used to treat the affected foliage.