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Lathyrus spp.

sweet peas and vetchlings

Fabaceae

Temperate Northern Hemisphere, with species in tropical East African mountains and temperate South America

Attracts Pollinators Attracts Butterflies Fragrant (moderate)Container Friendly

Native to North America

SunFull Sun

WaterMedium

HardinessZones 4–9

Overview

Lathyrus spp. is a genus of about 160 species of annual and perennial legumes in the pea family (Fabaceae), including the annual sweet pea (L. odoratus) and the perennial everlasting pea (L. latifolius). Most are climbing or scrambling plants 3-8 feet (1-2.5 m) long, holding on by branched tendrils at the tips of their pinnate leaves, though some species lack tendrils and form low clumps. The pea-type flowers are carried in long-stalked racemes in pink, purple, red, white, and blue, and several species are fragrant. Winged or angled stems are common across the genus. After flowering, plants form flattened pods that split to scatter the seeds. Like other legumes, Lathyrus spp. fixes nitrogen through root nodules. The seeds of several species, including the sweet pea and the grass pea (L. sativus), contain compounds that are poisonous if eaten in quantity. The genus is native chiefly to temperate regions and ranges from cottage-garden annuals to long-lived border perennials. Cool growing conditions suit most species, and flowering slows in summer heat.

Native Range

Lathyrus spp. is native mainly to temperate regions of the Northern Hemisphere, with further species in the mountains of tropical East Africa and in temperate South America. Several species occur naturally in North America, and others have naturalized there from gardens.

Suggested Uses

Grown on trellises, arches, and obelisks for cut flowers and vertical color, and allowed to scramble through shrubs or over banks. Perennial species cover fences and slopes, while annual sweet peas are grown for fragrance and cutting. Low tendril-less species suit the front of a border.

How to Identify

Identify Lathyrus spp. by its climbing or scrambling habit, pinnate leaves often ending in branched tendrils, and pea-shaped flowers in long-stalked clusters. Many species have conspicuously winged stems and leaf-like stipules at the base of each leaf. The flattened pods and tendril-tipped leaves separate it from vetches (Vicia spp.), which usually have many small leaflets and smaller flowers.

Appearance

Size & Dimensions

Height3' - 8'

Width/Spread1' - 3'

Reaches mature size in approximately 2 years

Colors

Flower Colors

red

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Spring Summer

Most Lathyrus spp. bloom from late spring into summer, with annual species flowering longest in cool weather and fading as heat builds. Perennial species flower over several weeks in midsummer. The fragrant species draw bees, which carry out pollination, though many flowers also self-pollinate.

Detailed Descriptions

Flower Description

pink, purple, red, white, or blue

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam

Drainagewell drained

Water & Climate

Water Needs

Medium

Time to Maturity

annual species bloom in 90-120 days; perennials in their second year

Care & Maintenance

Care Guide

Grow Lathyrus spp. in full sun in fertile, well-drained, neutral to slightly alkaline soil with a pH of 6.0-7.5 kept evenly moist. A trellis, netting, or other support lets the climbing species scramble upward. Annual sweet peas are sown in autumn or late winter for cool-season bloom, while perennial species return from the rootstock each spring. As nitrogen-fixing legumes the plants need little nitrogen fertilizer. Regular picking of flowers and removal of forming pods extends the bloom of annual types. Powdery mildew, aphids, and pea root diseases are the main problems.

Pruning

Annual species are pulled and composted once they finish in summer. Perennial species are cut back to the ground in late autumn or early spring after they die down. Pinching the tips of young seedlings encourages branching and a fuller, more floriferous plant.