The ‘Romance’ dahlia is cherished for its lush, layered blooms and generous summer-to-fall flowering season. This cultivar produces medium-sized flowers, typically measuring four to eight inches across. The dense, structured petals classify its form as a Formal Decorative or a Semi-Cactus, creating a soft, textured appearance. The color palette includes delicate blends of rosy pink, apricot, and cream, making it a vibrant choice for landscape display and as a cut flower.
Planting Site and Soil Preparation
Successful cultivation of the ‘Romance’ dahlia begins with selecting a site that receives a minimum of six to eight hours of direct sunlight daily, ideally with morning sun. Dahlias thrive in warm conditions, but they require protection from strong, persistent winds due to their height. The soil must be loose, rich, and extremely well-draining to prevent the tubers from rotting.
Gardeners should aim for a slightly acidic to neutral soil pH, ideally ranging between 6.5 and 7.0, which allows for optimal nutrient uptake. If the soil tests outside of this range, garden lime can be incorporated to raise the pH, while soil sulfur or gypsum can be used to slightly decrease it. Tubers should only be planted once the soil temperature consistently reaches 60°F (15°C), which is usually after the last expected frost date.
To plant, dig a hole six to eight inches deep, placing the tuber horizontally with the visible growth point, known as the “eye,” facing upward. Space the tubers about two feet apart for optimal air circulation and development, allowing the mature plants room to bush out. Cover the tuber with only two to three inches of soil initially, then gradually fill the remaining hole as the sprout grows above ground. Do not water the planting site immediately, as this can encourage the dormant tuber to rot before it establishes roots.
Essential Summer Maintenance
Once the dahlia sprouts have emerged above the soil line, a consistent watering regimen becomes necessary to support their rapid growth and eventual flowering. Deep watering is preferred over light sprinkling, ensuring the moisture penetrates the entire root zone, and the frequency should be adjusted based on weather conditions. Allowing the top layer of soil to dry slightly between waterings encourages a robust root system, though dahlias are heavy water users once established.
Fertilization is a scheduled process beginning about 30 days after planting, continuing every three to four weeks throughout the active season. Dahlias respond best to a low-nitrogen formula, such as a 5-10-10 or 10-20-20 NPK ratio, where the first number (Nitrogen) is lower than the other two (Phosphorus and Potassium). Using a high-nitrogen fertilizer will result in excessive, weak foliage growth at the expense of producing large, colorful blooms.
To maximize bloom production, attention must be paid to the plant’s structure. When the young plant develops three to four sets of leaves, “pinching” (removing the central growth tip) encourages branching, creating a bushier form with more flowering stems. Staking is necessary to support the heavy blooms and prevent wind damage; place a sturdy metal or bamboo stake at the time of planting. Deadheading, the removal of spent flowers, redirects the plant’s energy away from seed production, ensuring a continuous display of color until the first frost.
Protecting Against Pests and Disease
Monitoring foliage and blooms regularly is the most effective approach to managing the biological threats that affect dahlias. Common pests like slugs and earwigs primarily target tender new growth and emerging flower buds, leaving irregular holes and ragged edges. Spider mites thrive in hot, dry conditions and are identified by fine webbing and a stippled, bronze appearance on the undersides of leaves.
Intervention for these pests often involves non-chemical methods first, such as hand-picking slugs or using targeted insecticidal soap sprays for mite infestations. Fungal issues, like powdery mildew, appear as a white, dusty coating on the leaves, usually a result of high humidity and poor air circulation. This can be mitigated by improving plant spacing and applying a targeted fungicide early in the season.
A more serious concern is viral mosaic, which manifests as mottled, yellowed, or distorted foliage and leads to stunted plant growth. There is no cure for a viral infection in dahlias; the entire infected plant must be removed and destroyed immediately. This preventative measure avoids transmission to healthy plants by sap-sucking insects or through shared gardening tools.
Winterizing and Storage
As a tuberous perennial, the ‘Romance’ dahlia is not cold-hardy in most climates and requires lifting from the ground for winter storage after the growing season concludes. This process begins following the first hard frost, which signals the end of the season by turning the foliage black. The stems should be cut back, leaving a stalk of approximately four to six inches attached to the ground.
The tuber clump is then dug out of the soil, avoiding damage to the neck where the tuber joins the stem. After lifting, the clumps should air dry for 12 to 24 hours in a cool, shaded location to allow the skin to cure, which prevents rot during storage. While curing is important, the tubers must not be allowed to completely shrivel.
Successful winter storage requires maintaining a cool, consistent environment, ideally between 40°F and 50°F (4°C and 10°C), ensuring the temperature never drops below freezing. High humidity (75% to 85%) is necessary to prevent the tubers from dehydrating. Tubers can be stored in a breathable medium such as peat moss or vermiculite, placed in a container that allows air circulation, and should be checked monthly for signs of shriveling or decay.