How to Grow Streptocarpus 'Merton Blue'
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Streptocarpus 'Merton Blue'
Streptocarpus × hybridus 'Merton Blue'
flowerStreptocarpus 'Merton Blue' is a hybrid Cape primrose cultivar prized for its striking blue-purple flowers with contrasting darker veining. This compact, herbaceous perennial produces numerous delicate, trumpet-shaped blooms over an extended flowering season. It thrives as a houseplant or in sheltered outdoor environments in mild climates.
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Example Streptocarpus 'Merton Blue' timeline · Pittsburgh, PA (Zone 6b)
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Plant Streptocarpus 'Merton Blue'
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 Streptocarpus 'Merton Blue' blooms
Around Aug 15≈ 120 days after planting
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Growing Conditions
Soil
Growing Zones
Find your zone →Best grown indoors year-round in most regions; zones 10-11 for outdoor cultivation
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Propagation & Rooting
3-4 weeksLeaf cuttings or plantlets develop tiny roots and initial leaf growth
Maintain high humidity (70-80%), provide bright indirect light, keep soil lightly moist, use perlite or sand as propagation medium. Mist regularly but avoid wetting the cutting itself
Establishment & Vegetative Growth
4-6 weeksYoung rosette develops multiple leaves, crown expands, root system strengthens
Gradually acclimate to lower humidity, maintain consistent moisture, apply balanced liquid fertilizer every 2 weeks at half strength, ensure adequate air circulation
Bud Formation & Pre-flowering
3-4 weeksFlower buds appear along flowering stems emerging from crown; plant becomes compact and dense
Switch to blooming fertilizer higher in phosphorus, maintain bright light, continue consistent watering, remove any damaged foliage to direct energy to blooms
Flowering
6-10 weeks (can repeat throughout year with proper care)Blue-purple trumpet flowers with dark veining open progressively; multiple blooms appear continuously over weeks
Maintain bright indirect light, keep soil moist but not waterlogged, deadhead spent flowers to encourage new blooms, reduce nitrogen fertilizer, avoid temperature fluctuations
Post-flowering & Rest
2-3 weeksFlowers fade and drop; plant enters brief dormancy or reduced growth period
Reduce watering slightly, maintain bright light, cut back on fertilizer, allow brief cool period (60-65°F if possible), gradually resume feeding to trigger next bloom cycle
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Spray with neem oil or insecticidal soap; isolate infected plant; wipe foliage with alcohol-soaked cotton swab for light infestations
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Use yellow sticky traps; spray with insecticidal soap or neem oil; improve air circulation to deter; treat every 7-10 days for 3 weeks
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Increase humidity, mist foliage regularly, spray with neem oil or miticide; remove heavily infested leaves
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Use yellow sticky traps, spray undersides of leaves with insecticidal soap, ensure good air circulation
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Allow soil surface to dry slightly between waterings, use sand layer on soil surface, use yellow sticky traps, apply nematode-based biological control
Uses
Not for consumption
CulinaryStreptocarpus flowers and foliage are ornamental only and should never be ingested. They are not edible and contain no known culinary applications. [source]
Indoor decoration and air purification
HouseholdPrized as a long-flowering houseplant that brightens indoor spaces with continuous blue-purple blooms. Helps improve indoor air quality by absorbing airborne toxins through foliage. [source]
Cut flower arrangements
CraftDelicate blue trumpet flowers can be used in small floral arrangements and terrariums, though stems are relatively short. The flowers dry well for pressed flower crafts and botanical art. [source]
Pollinator attraction indoors
WildlifeWhen blooming near windows, the flowers attract beneficial insects like small flies and can provide early season nectar for indoor-visiting pollinators in transitional spaces. [source]
No traditional medicinal use
MedicinalWhile Streptocarpus species are not traditionally used in herbal medicine, the plant is completely non-toxic to humans and pets, making it safe for households with children and animals. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
This is an ornamental flower; 'harvest' by deadheading spent blooms to encourage continuous flowering. Pinch off faded flowers at the base of the stem. For propagation, harvest healthy mature leaves in spring, cut into sections, and propagate in perlite or sand medium under high humidity.
Fun Facts
- 🌱 Streptocarpus 'Merton Blue' is part of the Cape primrose family (Gesneriaceae) originating from South Africa, where wild species grow as epiphytes on shaded rock faces and tree trunks
- 🌱 The name 'Streptocarpus' comes from Greek words meaning 'twisted fruit,' referring to the characteristic spiral seed pods that develop after flowering
- 🌱 This cultivar can be propagated from a single leaf cutting, making it one of the easiest houseplants to multiply—a single mature leaf can produce dozens of plantlets
Gardening Terms
New to gardening? Learn about terms used in this guide:
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