How to Grow Calcutta Single
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Calcutta Single
Gladiolus grandiflorus 'Calcutta Single'
flowerCalcutta Single is a striking gladiolus cultivar known for its vibrant orange-red flowers with a distinctive single-petaled bloom form. This ornamental flower produces tall, elegant spikes that are highly prized for cut flower arrangements and garden displays. The cultivar is valued for its dramatic coloring and reliable performance in warm climates.
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Example Calcutta Single timeline · Pittsburgh, PA (Zone 6b)
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Plant Calcutta Single
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 Calcutta Single blooms
Around Jun 26≈ 70 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Calcutta Single dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 8-10; can be grown in zone 7b with winter protection
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Corm Dormancy & Planting
1-2 weeks until sproutingCorms are firm, dormant storage organs ready for planting in warm soil. The basal plate is visible at the bottom with dried roots.
Plant corms after soil temperature reaches 55°F (13°C). Ensure good drainage to prevent rot. Space 6-8 inches apart.
Stem Elongation & Spike Formation
2-3 weeksThe main flowering stem (spike) elongates rapidly with leaf emergence along the stem. A flower bud appears at the tip.
Maintain regular watering and fertilization. Provide staking or support if plants reach 3+ feet to prevent wind damage. Continue full sun exposure.
Flowering
2-3 weeks per spikeFlorets open sequentially along the spike from bottom to top, displaying vibrant orange-red blooms. Individual flowers are large and showy.
Deadhead spent flowers to encourage continued bloom. Cut spikes for arrangements when bottom 1-2 florets open. Keep soil consistently moist.
Seed Development & Corm Maturation
4-6 weeksAfter flowering, the plant focuses energy on developing new corms underground while the above-ground portions begin to decline. Seed pods may form if flowers are not cut.
Continue watering and fertilizing to support corm enlargement. Allow foliage to die back naturally. In frost-prone areas, lift corms after foliage dies, cure, and store for winter.
Common Pests
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Spray with water to dislodge; use miticide if severe. Increase humidity and maintain air circulation.
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Remove affected flowers; use insecticidal soap or neem oil. Monitor closely during warm weather.
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Treat corms before planting; use yellow sticky traps; apply systemic insecticide if needed.
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and
(Fusarium oxysporum)
Plant in well-draining soil; avoid overhead watering; remove affected corms immediately; rotate planting locations yearly.
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Spray with strong water stream; use insecticidal soap or neem oil for heavy infestations.
Uses
Ornamental Food Garnish
CulinaryGladiolus florets are edible and can be used to garnish salads and desserts, adding dramatic color and a slightly sweet flavor. The petals should be picked fresh and used immediately. [source]
Cut Flower Arrangements
HouseholdCalcutta Single's tall spikes and vibrant orange-red color make it a premium choice for floral arrangements, vases, and wedding bouquets. The long vase life (7-10 days) makes it practical for households. [source]
Dried Flowers & Crafts
CraftThe florets can be pressed and dried for use in crafts, scrapbooking, and botanical art. Dried spikes retain their color and structure well. [source]
Pollinator Support
WildlifeGladiolus flowers attract bees, butterflies, and other pollinators, making them valuable for supporting garden ecosystem health and biodiversity. [source]
Traditional Herbal Use
MedicinalIn some traditional medicine systems, gladiolus has been used to prepare infusions believed to have mild diuretic and anti-inflammatory properties, though scientific evidence is limited. [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 spikes in early morning when the bottom 1-2 florets are open for maximum vase life (7-10 days). Use a sharp knife and cut at an angle. Remove lower leaves that would sit below water level. Change water every 2-3 days and re-cut stems at an angle.
Fun Facts
- 🌱 The name 'Gladiolus' derives from the Latin word 'gladius,' meaning sword, referring to the sword-shaped leaves of the plant.
- 🌱 Calcutta Single produces flowers that open in a distinctive sequence from the bottom of the spike to the top, sometimes taking 2-3 weeks to fully open all florets.
- 🌱 Gladiolus corms have been cultivated and hybridized since the 18th century, with modern varieties like Calcutta Single developed through intensive breeding programs in horticulture centers worldwide.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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