How to Grow Flatpea
Flatpea
Lathyrus sylvestris
legumeFlatpea is a perennial legume with flattened seed pods and climbing or trailing growth habits. Native to Europe and western Asia, it has been cultivated for centuries as a livestock forage and nitrogen-fixing cover crop. The plant produces delicate flowers and distinctive flat, winged pods.
When should you plant Flatpea in your zone?
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Example Flatpea timeline · Pittsburgh, PA (Zone 6b)
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Plant Flatpea
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 Flatpea
Around Aug 15≈ 120 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Flatpea dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-8, prefers cool to temperate climates
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Get my Flatpea timeline →Growth Stages
Seedling
2-3 weeksSmall compound leaves emerge; plant develops initial root system with nodulating bacteria
Keep soil consistently moist but not waterlogged. No nitrogen fertilizer needed. Thin seedlings to proper spacing.
Vegetative Growth
4-8 weeksPlant develops climbing or trailing vines with pinnate compound leaves; establishing nitrogen-fixing nodules on roots
Provide support structure if desired. Water during dry periods. Monitor for early pest activity. Avoid excessive nitrogen fertilization.
Flowering
4-6 weeksDelicate purple, pink, or white flowers appear along stems in clusters; plant continues vine growth
Maintain consistent soil moisture to support flower production. Deadhead spent flowers to encourage continued blooming and seed production. Support vines as needed.
Pod Development
3-4 weeksDistinctive flat, winged pods (siliques) develop and enlarge; seeds inside continue filling
Reduce watering slightly to encourage pod maturation. Continue supporting vines. Watch for pod-feeding insects.
Seed Maturity & Harvest
2-4 weeksPods dry and turn brown or golden; seeds rattle inside when mature. Plant may begin senescence.
Allow pods to fully dry on the plant before harvest. Cut entire plant or individual pods. Thresh and dry seeds thoroughly for storage.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Remove infected pods, use row covers on young plants, early planting helps avoid peak weevil activity
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Spray with water to dislodge, insecticidal soap, encourage natural predators like ladybugs
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Increase humidity through irrigation, horticultural oils, predatory mites
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Hand-pick, neem oil spray, row covers on seedlings
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and
Copper barriers, diatomaceous earth, beer traps, handpicking
Uses
Historical Grain Legume
CulinaryFlatpea seeds were historically ground into flour and consumed as food in medieval Europe, though this use has largely been superseded by more productive legumes. The seeds are edible when cooked but require careful preparation to remove any anti-nutritional factors. [source]
Livestock Forage
CulinaryFlatpea is primarily used as high-protein forage for sheep, cattle, and other livestock. The plant provides excellent nutritional value with nitrogen content supporting animal growth and milk production. [source]
Nitrogen Fixation & Soil Improvement
HouseholdAs a perennial legume, flatpea forms symbiotic relationships with nitrogen-fixing bacteria, enriching soil with bioavailable nitrogen. This makes it invaluable as a cover crop and in sustainable agricultural rotations to reduce reliance on synthetic fertilizers. [source]
Pollinator & Beneficial Insect Support
WildlifeFlatpea's delicate flowers attract bees, butterflies, and other pollinators. The plant and its insect populations support broader ecosystem health and biodiversity in agricultural and garden settings. [source]
Ornamental Garden Interest
CraftWith its climbing vines and delicate flowers, flatpea can serve an ornamental function in gardens, particularly when grown on trellises. It adds vertical interest and texture to mixed plantings while providing ecological benefits. [source]
Harvest Tips
For forage, cut when plants are in early bloom stage for best nutritional value. For seed, allow pods to fully mature and dry on the plant; harvest when pods are brown and brittle, typically in late summer to early fall. Thresh dried pods by rubbing between hands or using a thresher. Store completely dry seeds in cool, dry conditions.
Fun Facts
- 🌱 Flatpea is one of the few perennial legumes that can persist and produce for multiple years, making it exceptionally valuable for long-term cover cropping and forage systems.
- 🌱 The distinctive flattened, winged seed pods (which give the plant its common name) are unique among Lathyrus species and aid in seed dispersal by wind and water.
- 🌱 Flatpea was traditionally used as a remedy in European folk medicine for various ailments and was mentioned in medieval agricultural texts as a reliable crop for poor soils.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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