The Manoa Dahlia is a captivating addition to any garden, offering vibrant color and texture. This tender perennial provides continuous blooms from summer until the first frost, making it a popular choice for its striking appearance and manageable care.
Understanding Manoa Dahlia
The Manoa Dahlia is a small formal decorative dahlia, producing 3 to 4 inch (7.5 to 10 cm) blooms. Its velvety, deep burgundy or dark red petals create a striking visual impact. The cultivar also features dark bronze-green foliage, which contrasts appealingly with its vibrant flowers. The plant typically reaches about 3 feet (1 meter) tall, suiting various garden settings.
Planting Manoa Dahlias
Manoa Dahlias thrive in full sun, needing at least six to eight hours of direct sunlight daily for abundant blooms. The soil should be well-drained, rich in organic matter, and have a slightly acidic to neutral pH (ideally 6.0-7.5). Before planting, loosen the soil to a depth of 12 inches (30 cm) and incorporate compost or well-rotted manure to improve drainage and fertility.
Plant Manoa Dahlia tubers in spring after the last frost, once soil temperature reaches at least 60°F (15°C). Dig a hole 3 to 6 inches (7.5 to 15 cm) deep, positioning the tuber with the sprout facing upwards. Space tubers 12 to 18 inches (30 to 45 cm) apart for proper air circulation and growth. After placing the tuber, backfill the hole, gently pressing the soil to remove air pockets, and water thoroughly.
Ongoing Care for Manoa Dahlias
After initial planting, avoid watering tubers until green sprouts appear above the soil, as overwatering can lead to rot. Once plants emerge and establish, deep watering is beneficial, typically two to three times per week, allowing the top inch of soil to dry between waterings. During hot, dry periods, increased watering frequency may be necessary.
Manoa Dahlias benefit from a low-nitrogen fertilizer, often called “bloom food,” with higher phosphorus and potassium. A 5-10-10 formula or similar is suitable. Begin fertilizing about 30 days after planting and continue every three to four weeks until September, ceasing fertilization to prepare tubers for overwintering.
Pinching the main stem when the plant reaches about 12 inches (30 cm) tall encourages branching and more flowers. Deadheading, the removal of spent blooms, redirects the plant’s energy from seed production into new buds, extending the bloom season. Since Manoa Dahlias grow up to 3 feet tall, staking is recommended to support stems and prevent breakage from wind or heavy blooms. Install stakes (e.g., bamboo or metal rods) at planting time to avoid damaging tubers, tying stems to the support as the plant matures.
Common Challenges and Solutions
Common pests include slugs, earwigs (which chew on leaves and flowers), and aphids (which feed on sap and can transmit viruses). Regularly inspecting plants and promptly removing pests by hand or using organic insecticidal soap can help manage these issues.
Powdery mildew, a fungal disease, can appear as white, powdery spots on leaves, especially in dry conditions. Ensuring good air circulation around plants and watering at the base of the plant rather than overhead can reduce its occurrence. If powdery mildew becomes prevalent, applying a fungicide can help control the spread. Maintaining overall plant health through proper watering and fertilization also strengthens the plant’s natural defenses against disease.
Overwintering Manoa Dahlia Tubers
In USDA Hardiness Zones 7 and colder, Manoa Dahlia tubers are not hardy and require lifting and indoor storage. After the first hard frost blackens the foliage, cut stems back to 2 to 4 inches (5 to 10 cm) above ground. Allow tubers to remain in the ground for one to two weeks after this frost to toughen their skins for storage.
To overwinter Manoa Dahlia tubers:
Carefully dig up tuber clumps, starting about a foot (30 cm) from the stem to avoid damage.
Gently brush off excess soil; avoid washing tubers, as this can introduce moisture and promote rot.
Air dry tubers for several days in a cool, frost-free location out of direct sunlight.
Once dry, store clumps in a ventilated container (e.g., cardboard box or plastic crate) filled with peat moss, clean wood shavings, or vermiculite.
Maintain an ideal storage temperature of 40 to 50°F (4.4 to 10°C) with moderate humidity (70-85%) to prevent shriveling or premature sprouting.
Check tubers monthly for rot or excessive dryness, adjusting storage conditions as needed.