How to Grow Thread-leaved Sundew
iNaturalist
Thread-leaved Sundew
Drosera filiformis
flowerDrosera filiformis is a carnivorous sundew native to the southeastern United States, characterized by ultra-thin, thread-like leaves covered in sticky tentacles that trap small insects. The plant produces delicate pink to red flowers on tall stalks and relies on insect digestion to supplement nutrients from poor, acidic soils. It is a fascinating specialty plant for bog gardens and carnivorous plant collections.
When should you plant Thread-leaved Sundew in your zone?
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Example Thread-leaved Sundew timeline · Pittsburgh, PA (Zone 6b)
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Plant Thread-leaved Sundew
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 Thread-leaved Sundew blooms
Around Jul 16≈ 90 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Thread-leaved Sundew dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 7-9; can be grown as a tender perennial or annual in cooler zones
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Get my Thread-leaved Sundew timeline →Growth Stages
Seed Germination
2-4 weeksTiny seeds germinate on moist peat surface; no cotyledons visible, seedlings appear as miniature rosettes
Maintain high humidity, bright light, and consistent moisture. Avoid fungal issues with good air circulation. Can take 2-4 weeks to germinate.
Seedling/Juvenile
4-8 weeksPlant develops thin, filiform leaves in a small rosette; early sundew tentacles become visible but are not yet productive
Provide bright light to encourage compact, bushy growth. Keep warm (65-75°F). Maintain constant moisture without waterlogging. Feeding insects is optional at this stage.
Vegetative Growth
6-10 weeksRosette expands with more numerous thread-like leaves; dense layer of red glandular tentacles fully develops on leaf surfaces
Ensure full sun to maximize tentacle production and color. Allow temperatures to fluctuate seasonally. Monitor for algae and fungal growth. Plant is now actively trapping insects.
Flowering
4-8 weeksTall, slender flower stalks emerge from the center of the rosette, bearing clusters of small pink to red flowers that open sequentially
Flowering is self-fertile; pollinate manually with a brush if desired to ensure seed set. Maintain moisture and light during blooming. Flowers last several weeks.
Seed Production & Dormancy
8-12 weeks or ongoingAfter flowering, plant produces numerous tiny seeds in capsules. Growth may slow in winter; some populations go semi-dormant
Allow seeds to mature on the plant or collect and store in cool, dry conditions. Reduce water slightly in winter but never let soil dry completely. Cool winter rest (50-60°F) may improve vigor.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Improve air circulation, reduce excess moisture on leaves, use yellow sticky traps, maintain cleanliness
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and
(Botrytis, Pythium)
Ensure adequate airflow, avoid overhead watering, use distilled water only, remove infected leaves, consider sulfur dust in severe cases
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Increase light, improve air circulation, reduce standing water on leaf surfaces, remove algae manually if severe
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Increase humidity, spray with water, provide good air circulation, use neem oil if necessary (test on small area first)
Uses
Carnivorous Plant Collector Specimen
CraftDrosera filiformis is highly prized by carnivorous plant enthusiasts for its exotic appearance and fascinating insectivorous behavior. Its long, delicate leaves and bright tentacles make it an eye-catching addition to specialized plant collections and bog gardens. [source]
Insect Population Control
WildlifeThe plant naturally traps and digests small flying insects (gnats, flies, mosquito larvae), providing biological pest management in addition to supplementing the plant's nutrient intake. In humid, warm environments, a single mature plant can catch significant numbers of insects. [source]
Historical Traditional Use
MedicinalDrosera species have been used in traditional European herbalism as expectorants and cough remedies; compounds like naphthoquinones are being studied for respiratory and antimicrobial properties. Modern herbalism still references sundew preparations, though scientific evidence remains limited. [source]
Natural Pest Control in Homes & Greenhouses
HouseholdGrowing sundews indoors or in greenhouses provides chemical-free control of gnats and small flying insects. A collection of carnivorous plants can significantly reduce pest populations in enclosed plant-growing spaces. [source]
Scientific & Educational Display
CraftDrosera filiformis is an engaging educational tool for teaching plant physiology, adaptation, and evolution. Schools and botanical institutions use it to demonstrate plant movement, nutrient uptake, and ecological specialization. [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 a non-edible ornamental; 'harvest' refers to seed collection. Allow flower stalks to mature fully; seeds are ready when capsules dry and turn brown/papery (typically 4-6 weeks after flowering). Cut seed heads into paper envelope, dry thoroughly, and store in cool, dry conditions. Seeds can remain viable for several years.
Fun Facts
- 🌱 The name 'sundew' comes from the glistening appearance of the sticky tentacles in sunlight, which resembles morning dew—this visual appeal lures insects to their doom.
- 🌱 Drosera filiformis has among the thinnest leaves of any carnivorous plant; its needle-like foliage is an adaptation to poor soils and can photosynthesize efficiently despite minimal surface area.
- 🌱 The plant can 'count' the number of insects touching its tentacles—sensory hair cells trigger successive waves of leaf curling to maximize digestive enzyme secretion only when prey contact is confirmed.
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