How to Grow Peanut Grass
Wikimedia Commons
Peanut Grass
Arachis repens
grassPeanut grass is a low-growing, creeping groundcover legume native to South America that forms dense mats 4-6 inches tall. It produces small yellow flowers followed by underground pod development similar to peanuts, and features compound leaves with a pleasant nutty aroma when crushed. This hardy perennial groundcover is valued for erosion control, nitrogen fixation, and its ability to thrive in poor soil conditions.
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Example Peanut Grass timeline · Pittsburgh, PA (Zone 6b)
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Plant Peanut Grass
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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Harvest Peanut Grass
Around Jun 16≈ 60 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Peanut Grass dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives best in zones 8-11; tolerates zone 7b with winter protection
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Establishment
4-6 weeksYoung plants develop initial roots and shoots; foliage is sparse, showing early compound leaves
Keep soil consistently moist but not waterlogged for 4-6 weeks. Water in early morning. Apply light mulch around plants (not touching stems) to retain moisture.
Vegetative Growth
4-8 weeksRapid lateral spreading with runner development; dense compound leaflets emerge; foliage deepens in color
Reduce watering frequency as plants establish. Maintain consistent moisture without flooding. Light fertilization rarely needed due to nitrogen fixation.
Flowering
6-12 weeks (spring through fall in warm climates)Small, bright yellow pea-like flowers appear along runners and throughout mat; flowers emerge from leaf axils
Flowers attract pollinators; allow them to bloom for wildlife benefit. Continue regular watering during bloom to support fruit development.
Podding & Maturation
4-8 weeksAfter pollination, flower stems elongate and push developing pods underground (geocarpy); mature pods form in soil beneath runners
Maintain adequate soil moisture to support pod development. Avoid heavy foot traffic that could damage developing pods.
Dormancy (Zone 8-9)
3-5 months (winter period)Foliage yellows and dies back with first frost; runners remain viable underground; crowns survive winter
Reduce winter watering significantly. In zones 8b-9, light mulch layer (1-2 inches) provides frost protection. Do not fertilize.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Increase humidity by overhead watering; spray with neem oil or insecticidal soap if severe; encourage predatory mites
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Rarely serious; remove by hand if present; allow natural predators to control populations
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Improve soil drainage; rotate with resistant cover crops; solarize soil if severely infested before planting
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and
Remove debris and improve drainage; hand-pick during early morning; set beer traps or use copper barriers
Uses
Low-Maintenance Groundcover & Lawn Alternative
HouseholdPeanut grass creates dense, attractive green mats that suppress weeds and eliminate mowing needs. Its shallow root system and spreading growth pattern make it ideal for erosion control on slopes, between hardscape, and in areas unsuitable for traditional turf. [source]
Pollinator Habitat & Native Bee Forage
WildlifeThe yellow flowers provide nectar and pollen for bees, butterflies, and beneficial insects. The dense mat also offers shelter for ground-nesting bees and beneficial arthropods. [source]
Nitrogen Fixation & Soil Improvement
HouseholdAs a legume, peanut grass forms symbiotic relationships with nitrogen-fixing bacteria, naturally enriching soil and reducing fertilizer requirements. This makes it valuable for improving poor or degraded soils over time. [source]
Ornamental Peanut Source
CulinaryWhile Arachis repens produces small, edible underground peanuts, harvesting is rarely pursued commercially. The nuts are viable but small compared to cultivated peanut varieties (Arachis hypogaea). [source]
Drought-Tolerant Xeriscaping
HouseholdOnce established, peanut grass thrives in arid and semi-arid regions with minimal supplemental water, making it an excellent choice for water-wise landscaping in western and southern climates. [source]
Harvest Tips
Peanut grass is a perennial groundcover—not typically harvested for food, but the creeping foliage can be trimmed back 2-3 times per year for shape maintenance. For edible peanuts (rarely done with this species), excavate pods in fall after foliage yellows. Clip back in early spring before new growth to remove dead winter material and encourage dense new foliage.
Fun Facts
- 🌱 Peanut grass exhibits geocarpy—the same seed-bearing mechanism as its close relative the cultivated peanut—where flower stems elongate after pollination and push developing pods into the soil to mature underground.
- 🌱 Unlike most groundcovers, peanut grass fixes atmospheric nitrogen through symbiotic bacteria in its root nodules, naturally fertilizing the soil and improving conditions for neighboring plants.
- 🌱 The plant's compound leaves close up at night (nyctinasty), a trait shared with many legumes, which may help conserve moisture and protect developing flower buds.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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