Dahlia ‘Cambridge’ is a captivating choice for gardeners, infusing landscapes with vibrant color and impressive blooms. This dahlia variety offers striking visual appeal, enhancing garden beds, borders, and container displays. Its consistent performance and prolonged season of beauty make it a favored addition for many garden enthusiasts.
Dahlia ‘Cambridge’ Characteristics
Dahlia ‘Cambridge’ features magnificent, fully double blooms, typically measuring 8 to 10 inches in diameter. These large flowers are classified as dinnerplate or decorative dahlias. Their petals display a vibrant yellow base, often speckled or streaked with rich red accents, creating a dramatic contrast and unique visual texture.
The plant exhibits an upright growth habit, commonly reaching 36 to 48 inches tall. Its strong stems support the large blooms, making ‘Cambridge’ an excellent choice for adding vertical interest. The dark green, glossy foliage provides a lush backdrop, highlighting the striking yellow and red flowers, which are also highly valued as long-lasting cut flowers.
Planting ‘Cambridge’ Dahlias
Plant Dahlia ‘Cambridge’ after the last threat of frost, when soil temperatures consistently reach at least 60°F. Select a site receiving a minimum of six to eight hours of direct sunlight daily. Well-draining, fertile soil is beneficial for optimal growth; amend it with compost or aged manure to improve its structure and nutrient content.
When planting tubers, dig a hole 4 to 8 inches deep, placing the tuber horizontally with any visible “eyes” or sprouts facing upward. Cover the tuber with a few inches of soil. Avoid watering immediately after planting unless the soil is exceptionally dry, as this helps prevent tuber rot before shoots emerge. Space individual tubers 18 to 24 inches apart to ensure ample room for development and air circulation.
Ongoing Care Practices
Once Dahlia ‘Cambridge’ plants establish and green shoots appear, a consistent watering regimen is important. Deep water two to three times per week, ensuring moisture penetrates 8 to 10 inches into the soil to reach the tuberous roots. Drip irrigation or soaker hoses are more effective than overhead watering, which can encourage fungal issues.
Dahlias are robust feeders, so a balanced approach to fertilization supports vigorous growth and prolific blooming. Apply a low-nitrogen fertilizer at planting, followed by one rich in phosphorus and potassium once the plants begin to produce their first blooms. Pinch the central stem when the plant reaches about 1 foot in height, down to the third or fourth set of leaves, to encourage bushier growth and more flowers.
Tall varieties like ‘Cambridge’ benefit from staking early to support their heavy blooms and prevent stems from toppling over in wind or rain. Regularly removing spent blooms, known as deadheading, encourages the plant to produce more flowers throughout the season.
Addressing Common Challenges
Dahlia ‘Cambridge’ can encounter common garden pests. Aphids, small pear-shaped insects, often cluster on new growth and suck plant sap, leading to distorted leaves. Slugs and snails cause irregular holes in leaves, particularly on young plants. Spider mites may cause stippling and discoloration, thriving in hot, dry conditions. Earwigs can also chew on leaves and flower petals, especially at night.
Fungal diseases like powdery mildew (white coating on leaves) and botrytis (gray mold, brown spots on flowers and leaves) can also affect dahlias. These often arise from high humidity or poor air circulation. Ensuring proper spacing between plants and watering at the base rather than overhead can help mitigate these issues. Prompt identification and interventions, such as a strong jet of water for aphids or hand-picking slugs, can help maintain plant health.
Overwintering Dahlia Tubers
In regions with cold winters (USDA Zones 3-8), Dahlia ‘Cambridge’ tubers are not hardy and must be lifted and stored. This process occurs after the first hard frost, which signals the end of the growing season and causes the foliage to blacken. Carefully dig up the tuber clumps, taking care not to damage them.
After digging, gently rinse excess soil from the tubers using a garden hose, but avoid scrubbing or bruising them. Allow the tubers to air dry for several days to a few weeks in a cool, well-ventilated area, which helps to cure them and prevent rot during storage.
Once cured, store the tubers in a cool, dark, and frost-free location, ideally between 38°F and 50°F, with about 75-85% humidity. Storage mediums include peat moss, vermiculite, or newspaper, placed in breathable containers like cardboard boxes or crates, ensuring good air circulation. Periodically check the stored tubers throughout winter, removing any that show signs of rot or shriveling to prevent issues from spreading.