How to Grow Oahu Catchfly

Oahu Catchfly

Silene stellata subsp. oahuensis

flower

Oahu Catchfly is a rare endemic flowering plant native to the Hawaiian island of Oahu, characterized by delicate pink or white star-shaped flowers and sticky calyces that trap small insects. This perennial wildflower typically grows in moist forest habitats and rocky cliff faces. It is critically endangered in its natural habitat due to habitat loss and invasive species competition.

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Example Oahu Catchfly timeline · Pittsburgh, PA (Zone 6b)

Plant Oahu Catchfly
Around Apr 17

Near Pittsburgh's average last spring frost.
Tend & protect
Late spring–summer

Watering, feeding, and pest-watch reminders.
First Oahu Catchfly blooms
Around Aug 15

≈ 120 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Oahu Catchfly dates for your own zip code.

Growing Conditions

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Sun: Partial shade, 4-6 hours of indirect sunlight daily; protect from intense afternoon sun in hot climates

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Water: Keep soil consistently moist but not waterlogged; mimics moist forest understory conditions. Water regularly during growing season; reduce slightly in winter dormancy if applicable

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Spacing: 12 inches

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Days to maturity: 120-180 days from seed to first flowering

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Planting depth: Surface sow or press seeds lightly into soil; requires light for germination

Soil

Type: Well-draining rocky or gravelly soil with organic matter; prefers slightly acidic to neutral soil

pH: 6.0-7.0

Amendments:

Peat moss or coco coir for moisture retention Perlite or pumice for drainage Composted bark Limestone chips to mimic volcanic rock substrate

Growing Zones

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Thrives in USDA zones 10-11; mimics tropical Hawaiian climate conditions

10a 10b 11a 11b

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Growth Stages

Seed Germination

2-4 weeks

Tiny seeds germinate on moist soil surface with light exposure; first cotyledons emerge within 2-3 weeks

Maintain consistent moisture and provide bright indirect light; avoid covering seeds; use bottom heat (65-70°F) to encourage germination; keep humidity moderate to prevent damping off

Seedling

4-8 weeks

Young plants develop true leaves and establish shallow root systems; growth is slow initially

Provide bright filtered light; keep soil moist; avoid transplanting until 2-3 true leaves appear; maintain moderate humidity; do not fertilize yet

Vegetative Growth

6-12 weeks

Plant develops rosette of basal leaves and upright stems; foliage thickens and root system deepens

Gradually increase light exposure; begin monthly dilute fertilizing with balanced fertilizer; maintain consistent moisture; provide air circulation to prevent fungal issues; stake stems if needed for support

Flowering

4-8 weeks (can be extended)

Delicate pink or white star-shaped flowers bloom on terminal inflorescences; sticky calyces trap small insects; flowers are aromatic

Continue consistent watering and partial shade; deadhead spent flowers to encourage continued blooming; avoid overhead watering to prevent flower damage; provide dilute monthly fertilizer high in phosphorus

Seed Development & Maturation

6-10 weeks

Flowers develop into seed capsules containing small black seeds; foliage may yellow slightly

Allow some flowers to remain for seed collection; reduce watering slightly once seeds mature; collect capsules when they turn brown and begin to split; store seeds in cool, dry conditions

Companion Planting

Plan your garden →

Plant with:

Hawaiian native sedges Ohi'a lehua (Metrosideros polymorpha) Native Hawaiian ferns Pukiawe (Styphelia tameiameiae) Native mosses and lichens

Avoid planting near:

Aggressive invasive species (Miconia calvescens, Clidemia hirta) Salt-tolerant weedy plants Allelopathic plants that inhibit growth Highly competitive non-native vegetation

Common Pests

Increase humidity; spray with water to dislodge; use neem oil or insecticidal soap if severe; ensure good air circulation
Allow soil surface to dry slightly between waterings; use yellow sticky traps; apply sand layer on top of soil; use Bacillus thuringiensis israelensis (Bti) if needed
Improve air circulation; avoid overhead watering; spray with sulfur or baking soda solution; remove affected leaves; reduce humidity in humid conditions
Use yellow sticky traps; spray neem oil on leaf undersides; increase air circulation; introduce parasitic wasps if available

Uses

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Native Hawaiian Pollinator Support

Wildlife

Silene stellata serves as a food source for endemic Hawaiian insects and native pollinators. The sticky calyces trap small insects which may serve ecological functions in the native Hawaiian ecosystem. [source]

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Native Plant Conservation & Restoration

Craft

This critically endangered species is cultivated in botanical gardens and conservation programs to prevent extinction and support habitat restoration efforts on Oahu. Propagating this plant contributes to biodiversity conservation. [source]

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Traditional Hawaiian Ethnobotany

Medicinal

As a native Hawaiian plant, it holds cultural and botanical significance in understanding traditional Hawaiian plant use and ecology, though specific medicinal applications require further ethnobotanical research. [source]

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Endemic Plant Biodiversity

Culinary

While not directly culinary, this species represents the unique botanical heritage of Hawaiian islands and the importance of preserving endemic plant species for ecosystem health. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

For seed collection, harvest mature brown seed capsules just as they begin to split naturally. Allow capsules to fully dry indoors in paper bags; extract seeds and store in cool (40-50°F), dry conditions in sealed containers. Flowers can be cut for arrangements when fully open but are delicate. This species is endangered, so prioritize conservation seed collection and propagation over ornamental harvesting.

Fun Facts

🌱 Silene stellata subsp. oahuensis is so rare and endemic to Oahu that it exists nowhere else in the world naturally, making it a living treasure of Hawaiian biodiversity.
🌱 The 'catchfly' common name refers to the sticky, viscid coating on the plant's calyces, which traps small insects—a unique evolutionary adaptation found in Silene species worldwide.
🌱 This subspecies is part of the broader Silene genus which includes over 700 species distributed across temperate and alpine regions globally, but this Hawaiian subspecies is a remarkable island endemic.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Damping Off Deadhead Germination Partial Shade Perennial pH Transplant True Leaves

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