How to Grow Hawaiian sandbur

Wikimedia Commons

Hawaiian sandbur

Cenchrus agrimonioides

grass

Hawaiian sandbur is a native Hawaiian grass species characterized by its distinctive burr-like seed heads and fine, wispy foliage. It is endemic to the Hawaiian Islands and plays an important ecological role in native plant communities. This warm-season grass is adapted to dry, sandy, and volcanic soils in coastal and lowland areas.

When should you plant Hawaiian sandbur in your zone?

Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.

Get my Hawaiian sandbur timeline →

Example Hawaiian sandbur timeline · Pittsburgh, PA (Zone 6b)

Plant Hawaiian sandbur
Around Apr 17

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

Watering, feeding, and pest-watch reminders.
Harvest Hawaiian sandbur
Around Jul 16

≈ 90 days after planting

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

Growing Conditions

☀️

Sun: Full sun, 6-8 hours daily minimum

💧

Water: Drought-tolerant once established; minimal supplemental watering needed. Water moderately during establishment phase; reduce watering as plant matures.

📏

Spacing: 12-18 inches inches

📅

Days to maturity: 90-120 days to flowering from seed

🌱

Planting depth: Surface sow or very shallow (0.125 inches); press seed firmly into soil

Soil

Type: Well-draining sandy or volcanic soil

pH: 6.0-7.5

Amendments:

Compost or aged manure for organic matter Perlite or coarse sand for drainage Volcanic cinder or pumice in Hawaiian contexts

Growing Zones

Find your zone →

Thrives in zones 10b-12b; primarily suited to Hawaii and warm tropical climates

10b 11a 11b 12a 12b

Get my Hawaiian sandbur timeline →

Growth Stages

Seed Germination

7-14 days

Tiny seedlings emerge with fine, hair-like cotyledons; minimal visible growth above soil

Keep soil surface moist but not waterlogged; provide bright light; protect from wind damage

Seedling & Early Growth

3-4 weeks

First true leaves appear; grass develops thin, delicate blade structure; height 2-4 inches

Maintain consistent moisture; reduce watering gradually; begin light fertilization if needed

Vegetative Development

4-8 weeks

Plant produces tillers (shoots); fuller clump formation; height 8-18 inches; root system deepens

Water less frequently, allowing soil to dry between watering; full sun exposure critical; no fertilizer needed for native stands

Flowering & Seed Production

4-6 weeks

Distinctive burr-like inflorescences (seed heads) form; characteristic spiny involucre develops; height 12-24 inches

Reduce or cease watering; allow plants to dry down; do not deadhead if seed dispersal is desired

Seed Maturity & Dormancy

Variable, typically 4-8 weeks into dry season

Seed heads harden and become spiky; foliage may brown; plant enters dry season dormancy

Minimal or no water needed; collect seed if desired before natural dispersal; plants persist through dry season

Companion Planting

Plan your garden →

Plant with:

Ilima Nai'a Uluhe Other native Hawaiian coastal grasses Native Hawaiian shrubs adapted to dry conditions

Avoid planting near:

Invasive grass species that compete aggressively Moisture-loving plants that require frequent irrigation Shade-producing trees or structures

Common Pests

Hand-pick affected shoots; remove heavily infested plants; encourage native predators; rarely requires intervention in native contexts
Usually tolerate grazing; no control needed in native plantings; remove by hand if severe
Spray with horticultural oil if present; rarely problematic in outdoor native plantings

Uses

🦋

Habitat Restoration & Native Ecology

Wildlife

Hawaiian sandbur is an important native grass in Hawaiian coastal and lowland ecosystems, providing food and shelter for native Hawaiian insects, birds, and other wildlife. It helps stabilize sandy soils and restore degraded native plant communities. [source]

🏠

Ornamental & Landscape Use

Household

The fine texture and distinctive burr seed heads make it an attractive ornamental grass for dry gardens, coastal landscapes, and Hawaiian-themed gardens. It provides year-round interest with minimal maintenance. [source]

🦋

Erosion Control

Wildlife

The root system stabilizes sandy and volcanic soils, preventing erosion in coastal and lowland areas. It is valuable for habitat restoration and land management projects. [source]

🦋

Drought-Resistant Landscaping

Wildlife

As a highly drought-tolerant native species, Hawaiian sandbur is ideal for water-wise landscaping, particularly in Hawaii and tropical regions with dry seasons. It reduces the need for supplemental irrigation. [source]

Harvest Tips

For seed collection, harvest burrs when fully mature and dried (typically 4-6 weeks after flowering), before natural dispersal. Clip seed heads into a bag or cloth; allow to dry further indoors. For native habitat restoration, allow natural seed dispersal without harvest.

Fun Facts

🌱 The distinctive burr-like seed heads of Hawaiian sandbur evolved to attach to animal fur and clothing, aiding seed dispersal across the Hawaiian Islands.
🌱 Hawaiian sandbur is endemic to Hawaii and found naturally only in specific coastal and lowland habitats, making it a unique island species.
🌱 The genus Cenchrus includes several species globally adapted to sandy soils, but Hawaiian sandbur (C. agrimonioides) is the only native sandbur grass species in the Hawaiian Islands.

Gardening Terms

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

Deadhead Full Sun Native Plant pH True Leaves

Shop Hawaiian sandbur plants and related plants at Plant Addicts →

Join 30,000 gardeners planning their gardens with LizPlants.

Get your personalized Hawaiian sandbur planting timeline

Tell us your zip code and we'll calculate exactly when to start Hawaiian sandbur seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.

Get my Hawaiian sandbur timeline →