The ‘Red Rock’ dahlia is a stunning addition to any garden, known for its vibrant display. This popular variety adds rich color and visual interest, making it a focal point in beds, borders, or as a cut flower.
Understanding Red Rock Dahlias
The ‘Red Rock’ dahlia is a formal decorative dahlia, distinguished by its large, double blooms. Each blossom features deep scarlet petals often edged with a pearly white, creating a striking contrast. The plant typically reaches a height of about 3 feet and blooms from mid-summer into early fall, providing a long season of vibrant color.
Planting Red Rock Dahlias
Plant ‘Red Rock’ dahlia tubers after the last frost, when soil temperature reaches at least 60°F (15°C). A site offering 6 to 8 hours of direct sunlight daily is ideal for optimal growth. The soil should be well-draining and rich, with a pH between 6.0 and 7.5. Amending heavy clay soil with compost or aged manure improves drainage and aeration.
Dig a hole 4 to 6 inches deep and wide enough for the tuber. Place the tuber horizontally with the growing points, or “eyes,” facing upwards. Cover with 2 to 3 inches of soil initially, gradually filling in as the stem sprouts. Space tubers 12 to 24 inches apart to allow for growth and air circulation. Avoid watering immediately after planting; wait until green shoots emerge to prevent tuber rot.
Care and Maintenance
Once established, consistent watering is important. Aim for about 1 inch of water per week, adjusting frequency based on climate and soil type; daily watering may be necessary in hot, dry conditions. Deep watering encourages a strong root system. For fertilization, avoid high-nitrogen formulas, which promote leafy growth over blooms. Use a fertilizer designed to encourage flowering, applying it throughout the growing season.
Regular deadheading, or removing spent blooms, encourages continuous flowering by preventing seed production. As ‘Red Rock’ dahlias can reach about 3 feet in height and produce large double blooms, they benefit from support. Install sturdy stakes near the tuber at planting time to avoid damaging roots later, tying stems to the stakes as the plant grows to prevent bending or breaking.
Addressing Common Challenges
Common issues when growing ‘Red Rock’ dahlias include a lack of blooms, often due to too much nitrogen in fertilizer, which encourages foliage growth. Insufficient sunlight (less than 6 hours daily) also inhibits blooming. Watering inconsistencies, either too little or too much, affect flower production.
Pest infestations, such as aphids or slugs, occur; regular inspection aids early detection. If buds are not opening, small holes might indicate pests like thrips or earwigs. Fungal diseases, such as powdery mildew, affect dahlias, worsened by poor air circulation or overhead watering. Proper spacing and watering methods mitigate these issues.
Overwintering Red Rock Dahlias
In colder climates (USDA Zones 3-7), ‘Red Rock’ dahlia tubers must be lifted and stored indoors for winter. Dig up tubers after the first hard frost causes foliage to die back. Allowing them to remain in the ground for a week or two after this initial frost helps tubers mature and improves storage viability.
- Cut stems back to 5-6 inches above ground.
- Carefully dig and lift the tuber clump without damage.
- Rinse off soil, avoiding skin punctures.
- Dry and cure tubers in a well-ventilated area, away from direct sunlight, for 1-2 days.
- Store cured tubers in a cool, dark, frost-free location (40-50°F / 4-10°C, 80-90% humidity).
- Pack in peat moss, vermiculite, wood shavings, or newspaper, ensuring air circulation and checking periodically for rot or shriveling.