How to Grow St. Brigid
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St. Brigid
Dahlia × pinnata 'St. Brigid'
flowerSt. Brigid is a semi-double to double-flowered dahlia cultivar prized for its vibrant, fully-petaled blooms in a range of colors including red, pink, white, orange, and purple. These dahlias are popular cut flowers, known for their long vase life and striking appearance in arrangements. The plant grows as a tender perennial, typically treated as an annual in cooler climates.
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Example St. Brigid timeline · Pittsburgh, PA (Zone 6b)
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Plant St. Brigid
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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First St. Brigid blooms
Around Jun 26≈ 70 days after planting
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 9-11; grown as annuals in zones 3-8 with tuber storage
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Tuber/Transplant
1-2 weeks before sproutingDahlia tubers or young transplants are planted in spring after frost danger passes. Tubers should show an 'eye' or sprout point.
Plant after last frost date when soil is warm (60°F+). Ensure good drainage. Water lightly until growth begins. Stake or plan support structure.
Vegetative Growth
4-6 weeksPlant emerges with compound leaves and develops a bushy habit. Stems grow taller and branch, building the framework for flower buds.
Pinch out the central growing tip when plant reaches 12 inches tall to encourage branching. Apply balanced fertilizer every 2-3 weeks. Maintain consistent moisture. Install supports early.
Budding & Flowering
8-12 weeks or until frostTerminal buds form at branch tips and develop into the characteristic double flowers. Blooms appear in waves throughout mid-summer to fall.
Deadhead spent flowers regularly to encourage more blooms. Switch to lower-nitrogen, higher-phosphorus fertilizer to support flowering. Continue staking as flower weight increases. Watch for pests.
Peak Bloom
6-10 weeksPlant produces abundant, fully-double flowers in brilliant colors. Blooms reach full size and color intensity.
Harvest flowers in early morning for best vase life. Cut at least one-third of stem length for arrangements. Keep well-watered and deadheaded.
Senescence & Tuber Storage
4-6 months dormancy (winter)After first frost, foliage dies back. Underground tubers are dormant and ready for harvest and storage.
In cold climates, dig tubers after frost blackens foliage. Let dry 1-2 weeks in cool, airy place. Store in peat moss or sawdust at 40-50°F over winter. In warm zones, allow foliage to die naturally or cut back.
Common Pests
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Hand-pick in early morning; use row covers; apply neem oil or spinosad; encourage parasitic wasps and milky spore in soil
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Increase humidity by misting foliage; spray with water to dislodge; use insecticidal soap or neem oil; ensure good air circulation
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Remove damaged flowers; use blue sticky traps; spray with spinosad or insecticidal soap; avoid excessive nitrogen fertilization
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Improve air circulation; avoid wetting foliage; spray with sulfur or potassium bicarbonate; remove infected leaves
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Hand-pick at dusk; use copper tape barriers; set beer traps; encourage ground beetles; apply diatomaceous earth
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Use yellow sticky traps; spray neem oil or insecticidal soap; encourage parasitic wasps; vacuum with handheld device
Uses
Edible Flowers
CulinarySt. Brigid dahlia petals are edible and add striking color and mild flavor to salads, desserts, and cocktails. Remove the bitter white base at the petal center for better taste. [source]
Cut Flower Arrangements
HouseholdSt. Brigid dahlias are among the finest cut flowers, prized by florists and gardeners for their long vase life (7-10 days), full double form, and range of vibrant colors. They are excellent for wedding bouquets, table centerpieces, and floral design. [source]
Pollinator Support
WildlifeDahlia flowers attract bees, butterflies, and other beneficial pollinators to the garden. While double-flowered varieties like St. Brigid have reduced pollen accessibility compared to open-centered forms, they still provide nectar and pollen resources. [source]
Dried Flowers & Craft Projects
CraftSt. Brigid dahlia petals and whole blooms dry well and can be used in pressed flower art, dried arrangements, resin crafts, and other decorative projects. Hang stems upside-down in a cool, dark, airy location for best results. [source]
Traditional Folk Remedies
MedicinalIn some traditional medicine systems, dahlia tubers and flowers have been used to support digestive health and as mild diuretics, though scientific evidence is limited. Use only under guidance of qualified practitioners. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Cut flowers in early morning when stems are fully hydrated. Cut at least one-third of the stem length above a leaf node. Re-cut stems at a 45-degree angle and place immediately in cool water with floral preservative. Dahlia flowers typically last 7-10 days in a vase. Deadhead spent flowers on the plant to promote continuous blooming. Harvest tubers after the first hard frost when foliage blackens; dig carefully, cure for 1-2 weeks, and store in cool, dry conditions.
Fun Facts
- 🌱 St. Brigid dahlias are named after the Irish saint and are popular in Irish and Celtic gardens. The variety was developed by Irish breeders in the late 19th and early 20th centuries.
- 🌱 Dahlia tubers can be stored and replanted year after year, making them economical perennials in cold climates. A single tuber planted in spring can produce 50+ cut-quality flowers by fall.
- 🌱 The dahlia was the national flower of Mexico before the Spanish imported it to Europe in the 16th century, where it was hybridized extensively into the hundreds of varieties we see today.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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