Dahlia ‘Ambition’ is a highly sought-after variety, captivating gardeners with its striking appearance and prolific blooms. Its distinct color and form make it a focal point in any garden setting, offering both beauty and abundant flowers.
Characteristics of Dahlia Ambition
Dahlia ‘Ambition’ features an intense deep purple to magenta coloration, often with hints of reddish-purple. Its serrated petals contribute to a semi-cactus or fimbriated decorative form. These fully double flowers can reach 10 to 20 centimeters (4 to 8 inches) in diameter. Plants grow to 100 to 120 centimeters (40 to 47 inches) tall with a 60-centimeter spread. Blooming extends from July until the first significant frost, providing color throughout late summer and autumn.
Essential Growing Conditions
Optimal growth for Dahlia ‘Ambition’ requires a site with ample sunlight, ideally at least six to eight hours of direct sun daily. While full sun is preferred, light afternoon shade can be beneficial in hot climates. Soil should be well-draining and rich in organic matter to prevent waterlogging and tuber rot. A slightly acidic to neutral pH (6.0-7.5) supports healthy nutrient uptake. Consistent moisture is necessary during the growing season, but avoid overwatering, especially immediately after planting.
Planting and Ongoing Cultivation
Dahlia ‘Ambition’ tubers should be planted outdoors after the last threat of frost has passed, typically when soil temperatures consistently reach 15°C (60°F) or warmer. Place the tubers about 10 to 15 centimeters (4 to 6 inches) deep with the “eye” or sprout facing upwards. Spacing tubers approximately 30 to 75 centimeters (12 to 30 inches) apart allows for adequate air circulation and growth. Inserting a sturdy stake at planting time is advisable for these tall varieties to provide support as they grow, preventing wind damage or bending.
Once the plants reach about 15 centimeters (6 inches) in height, a balanced fertilizer can be applied. Follow with a low-nitrogen, high-phosphorus, and potassium formula every two to four weeks throughout the growing season to encourage abundant blooms.
When the plants are approximately 30 centimeters (12 inches) tall, pinch out the central growing tip just above a set of leaves. This promotes bushier growth and increases the number of flowers. Regularly removing spent blooms, a process known as deadheading, redirects the plant’s energy into producing new flowers instead of seeds, extending the blooming period.
Common Pests and Diseases
Dahlia ‘Ambition’ can encounter several common garden pests. Slugs and snails frequently target young, tender shoots, leaving irregular holes in foliage. Earwigs may chew on leaves and flower buds, particularly at night.
Sap-sucking insects like aphids, spider mites, and thrips can cause yellowing, curling, or distortion of leaves and may transmit viral diseases. Spider mites thrive in hot, dry conditions, often indicated by fine webbing on leaf undersides.
Fungal diseases, such as powdery mildew, appear as a white, powdery coating on leaves, especially in humid conditions or with poor air circulation. Botrytis, or gray mold, can cause brown spots and fuzzy gray growth on leaves and flowers, particularly in cool, wet weather. Root rot is a risk in overly wet or poorly draining soils, leading to plant decline.
Viral issues, characterized by distorted growth, stunting, or yellowing veins, typically cannot be cured. Infected plants should be removed to prevent spread. Maintaining good garden hygiene, proper plant spacing, and avoiding overhead watering can help mitigate many of these issues.
Winter Dormancy and Storage
For gardeners in colder climates (USDA zones 3-7), Dahlia ‘Ambition’ tubers must be lifted and stored indoors for winter to prevent freezing damage. After the first hard frost causes the foliage to turn brown and mushy, allow the tubers to remain in the ground for an additional one to two weeks. This period helps the tuber skins toughen for storage.
Once dug, gently brush off excess soil from the tuber clumps. Tubers can be washed, then cured for a few days in a cool, dark, and humid environment, avoiding direct sunlight or forced air that could dry them out too quickly.
Store tubers in a frost-free location where temperatures remain consistently between 7°C and 10°C (40°F to 50°F). Ideal storage mediums include peat moss, vermiculite, wood shavings, or sand, which help maintain appropriate moisture levels and prevent desiccation. Store the tubers in well-ventilated containers such as cardboard boxes or mesh bags. Periodically check the stored tubers throughout winter for any signs of rot or shriveling, removing affected ones to prevent spread and adjusting humidity if needed.
Multiplying Your Ambition Dahlias
The most common and effective method for multiplying Dahlia ‘Ambition’ is through the division of its tubers. This process is typically performed in late winter or early spring while the tubers are still dormant, though some find it easier in spring as eyes begin to swell and become more visible.
Each viable division must consist of a piece of tuber that has a healthy “eye” (a small bud or sprout) and an unbroken “neck” connecting it to the main crown. The body of the tuber provides the necessary stored energy for the new plant to grow.
Begin by gently separating the tuber clump, carefully cutting through the crown to ensure each section retains an eye, neck, and firm tuber. Sterilizing cutting tools between clumps helps prevent the spread of potential diseases.
While tuber division is the primary method for home gardeners, dahlias can also be propagated from cuttings taken from actively growing shoots in early spring. A single well-grown dahlia plant can yield multiple new tubers each season, providing an economical way to expand your collection.