How to Grow Cool of the Evening
Wikimedia Commons
Cool of the Evening
Ipomoea nil 'Cool of the Evening'
vineCool of the Evening is a striking morning glory cultivar featuring large, deep purple-blue flowers with white markings that resemble a star or flame pattern. This fast-growing annual vine blooms prolifically throughout summer and fall, with flowers opening in early morning and closing by afternoon. It's prized by gardeners for its dramatic color contrast and rapid coverage of trellises, arbors, and fences.
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Example Cool of the Evening timeline · Pittsburgh, PA (Zone 6b)
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Plant Cool of the Evening
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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Harvest Cool of the Evening
Around Jun 6≈ 50 days after planting
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-10 as an annual; perennial in zones 9-11
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Germination & Seedling
2-3 weeksSeeds sprout within 7-14 days; seedlings develop first true leaves and begin climbing behavior.
Soak seeds 24 hours or scarify lightly to improve germination. Keep soil warm (70-80°F) and consistently moist but not waterlogged. Provide bright light and high humidity.
Vegetative Growth
3-4 weeksRapid vine development with heart-shaped green leaves climbing and twining around supports; no flowers yet.
Install sturdy trellis or support early. Water regularly and maintain consistent moisture. Pinch tips if bushier growth desired. Feed every 2-3 weeks with balanced fertilizer.
Budding & Early Flowering
2-3 weeksFlower buds form along vine; first blooms appear, typically deep purple with white star/flame markings.
Reduce nitrogen fertilizer to encourage flowering over foliage. Continue regular watering. Support vines as they become heavier with blooms. Deadhead spent flowers to promote more blooms.
Peak Flowering & Flowering Maintenance
6-10 weeksAbundant blooms open each morning, creating dramatic color display; vine is fully mature and productive.
Continue deadheading. Water consistently but avoid overwatering. Monitor for pests. Provide phosphorus-rich fertilizer (low nitrogen) every 2 weeks to sustain flowering.
Late Season & Decline
Until first frostFlowering continues but may slow in late fall as temperatures drop; vine may produce seed pods if flowers are left on vine.
Allow some flowers to mature to seed if desired for self-sowing next year. Frost will kill vine; remove plant before first hard freeze or allow to die back naturally.
Common Pests
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Hand-pick in early morning or use neem oil spray; apply row covers in late spring
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Increase humidity with regular misting; spray with water or insecticidal soap; neem oil for severe infestations
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Use yellow sticky traps; spray with insecticidal soap or neem oil weekly until controlled
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Spray with strong water stream to dislodge; use insecticidal soap or neem oil; introduce ladybugs
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Remove affected leaves; use reflective mulch; spinosad spray for severe cases
Uses
Garden Trellis & Screening
OrnamentalCool of the Evening rapidly covers arbors, trellises, fences, and pergolas with dramatic purple and white blooms, providing living privacy screens and vertical garden interest. The compact morning blooms create a stunning daily display. [source]
Fresh Cut Flower Arrangements
CraftThe striking deep purple flowers with white markings make beautiful additions to morning floral arrangements. Cut early morning while blooms are fresh and display life is longest. [source]
Pollinator Attraction
WildlifeMorning glories attract bees, butterflies, hummingbirds, and other pollinators throughout the blooming season, supporting garden biodiversity and nearby plant pollination. [source]
Edible Flowers
CulinaryMorning glory flowers are completely non-toxic and can be used as edible garnishes for salads and desserts, adding visual appeal and delicate flavor to culinary presentations. [source]
Harvest Tips
Morning glories are ornamental vines; no traditional harvest. Enjoy fresh flowers each morning by viewing them in situ. If desired, allow some flowers to fade and develop seed pods for seed collection in late fall (pods will dry and split open naturally). Store seeds in cool, dry place over winter for next season.
Fun Facts
- 🌱 Cool of the Evening flowers open precisely at dawn and close by midday or early afternoon—a survival mechanism to conserve moisture and protect pollen in heat, giving the variety its poetic name.
- 🌱 Morning glories (Ipomoea) have been cultivated for thousands of years; Japanese breeders developed elaborate ornamental varieties called 'asagao' (朝顔), and Cool of the Evening is considered a premium exhibition cultivar in Japan.
- 🌱 The vines can grow 6-10 feet (or more) in a single season, making them among the fastest-growing annual vines and ideal for last-minute garden screening or trellis coverage.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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