The ‘Jean Marie’ Dahlia is a favored choice for many gardeners, celebrated for its striking appearance and versatility. This dahlia variety brings a vibrant display to garden beds and provides excellent material for cut flower arrangements.
Understanding the ‘Jean Marie’ Dahlia
The ‘Jean Marie’ Dahlia is a decorative dahlia, often reaching “dinnerplate” size. Its fully double blooms typically measure 6 to 10 inches wide. This variety is noted for its captivating color palette, featuring rich purple petals delicately edged with white. Some descriptions also suggest hints of pink or lilac within the purple. These substantial blooms are held upright on strong stems, making them suitable for cut flowers. The plant grows 3 to 4 feet (90-120 cm) tall.
Planting ‘Jean Marie’ Dahlias
Plant ‘Jean Marie’ dahlia tubers after the last spring frost, once soil temperatures consistently exceed 60°F (15°C). Choose a site that receives at least 6 to 8 hours of direct sunlight daily. In hotter climates, morning sun with some afternoon shade can be beneficial.
Dahlias thrive in rich, well-draining soil with a pH between 6.0 and 7.5. Before planting, amend heavy clay soils with organic matter like compost or well-rotted manure to improve drainage.
Dig a 4 to 6-inch deep hole, placing the tuber horizontally with the “eye” facing upwards. Space tubers 12 to 18 inches apart and cover with 2 to 3 inches of soil. Avoid watering immediately after planting, as excessive moisture can lead to tuber rot before sprouts appear. Water only once new green shoots become visible.
Ongoing Care for ‘Jean Marie’ Dahlias
Once established, ‘Jean Marie’ dahlias require consistent, deep watering, typically 2 to 3 times per week, or more frequently during hot, dry periods. Deep watering ensures moisture reaches the tubers’ roots, encouraging a robust root system. Avoid frequent, shallow watering, as this can lead to poor blooming.
Dahlias require ongoing nutrition throughout their active growing season. Apply a balanced organic fertilizer, or one with a lower nitrogen content (e.g., 5-10-5 NPK), after plants are established. Too much nitrogen promotes lush foliage at the expense of flower production. Support tall varieties with stakes to prevent stems from bending or breaking. This can be done at planting time or when plants are about 2 feet tall.
Pinching, or “topping,” young dahlia plants (10 to 12 inches tall with at least four sets of leaves) encourages bushier growth and more blooms. This involves removing the central growing tip above a leaf node, redirecting the plant’s energy into developing lateral shoots. While pinching delays the first blooms, it significantly increases flower production. Deadheading spent flowers prevents the plant from expending energy on seed production and encourages continuous blooming until the first frost.
Harvesting and Overwintering
Regular harvesting of ‘Jean Marie’ dahlia blooms promotes continuous flowering. The best time to cut flowers is in the cool morning hours, after the dew has dried but before the heat of the day. Select blooms that are one-half to two-thirds open, as dahlias generally do not open further once cut.
Cut stems at least 12 inches long, making the cut above a leaf node to encourage new growth. Immediately after cutting, place stems into cool water or use a hot water treatment (160-180°F) for about an hour to improve vase life. Remove any leaves below the waterline to prevent bacterial growth.
In regions with freezing winters (USDA Zones 3-8), ‘Jean Marie’ dahlia tubers must be dug up and stored indoors. Wait until after the first hard frost causes foliage to die back, typically 10 to 14 days later. This allows the plant to send starches back to the tubers, aiding their viability for the next season.
Cut stalks back to 4 to 6 inches from the ground, then carefully dig around the tuber clump about a foot away from the stem. Rinse off excess soil and allow tubers to dry for several days to a few weeks in a cool, dry, well-ventilated area, away from direct sunlight. This curing helps prevent rot during storage.
Store cleaned, dried tubers in a cool, dark, dry location (ideally 40-45°F / 4-7°C) in a medium like peat moss, vermiculite, or wood shavings. Ensure good air circulation and check periodically for rotting tubers.
Troubleshooting Common Issues
‘Jean Marie’ dahlias may not bloom or can exhibit leggy growth due to several factors. Insufficient sunlight (less than six hours daily) is a frequent cause of poor flowering and weak stems. Over-fertilization, particularly with high-nitrogen formulas, can result in lush foliage but few flowers, as the plant prioritizes vegetative growth. To address this, ensure adequate light exposure and use a balanced or lower-nitrogen fertilizer.
Common dahlia pests include aphids, spider mites, slugs, snails, earwigs, and thrips.
Aphids and spider mites, often found on leaf undersides, cause yellowing and stunted growth. Control with insecticidal soap, neem oil, or natural predators.
Slugs and snails, which leave irregular holes in leaves, are managed with barriers like copper tape or diatomaceous earth.
Earwigs chew on blooms and leaves; remove garden debris and use traps.
Thrips deform flowers and discolor leaves; manage with sticky traps or beneficial insects.
Dahlias are susceptible to diseases such as powdery mildew and root rot. Powdery mildew appears as white, powdery spots on leaves and can be managed with organic treatments like a baking soda solution. Root rot often results from overwatering or poorly draining soil; prevent it by ensuring proper soil amendments and avoiding excessive moisture. Maintaining good air circulation and consistent watering practices help prevent many common dahlia problems.