How to Grow Lathyrus Plants

Guide to Growing Sweet Pea, Bitter Vetch, Perennial Peavine, and Everlasting Pea

Perennial varieties of Lathyrus reach heights of between 60 cm and 3 m (2 to 10 feet). They bloom from the late spring through summer with fragrant butterfly like leaves. Visit this page of the site for information on How to grow Annual Lathyrus plants.

Lathyrus odoratus
Lathyrus odoratus – Sweet pea by Carl E Lewis; creative commons.

They can be grown as trailing plants or attached to a trellis or fence.

Some common names for Lathyrus include Sweet pea, Lord Anson's blue pea, Perennial pea, and Everlasting pea.

Lathyrus latifolius
Lathyrus latifolius – Everlasting Pea by Amandabhslater.

How to Grow Sweet Pea and other Lathyrus Plants

When growing Sweet pea and other Lathyrus members outdoors from the off. It is best to prolong the start of the growing season by protecting the soil with a layer of black plastic, This will help to keep the soil warm.

Slits should be made in the plastic and the sweet pea seeds sown at a depth of 6 mm (1/4 inch) at the start of spring.

The plants will take about three to four weeks to germinate. As soon as they get to about 10 cm (4 inches) in height, apply a mulch to the sweetpea plants.

Sweet pea can grow in either a sunny or lightly shaded part of the garden.

They prefer a soil of pH 6 to 7.5, as with Annual Lathyrus, the soil should be deeply composted (40 cm; 16 inches) and have bone meal added to it.

If first preparing Lathyrus seedlings indoors, then start the growing process about 7 or 8 weeks before due to be transplanted out.

First chip the seeds then imbibe them in warm water for a day. They will require to be inoculated with nitrogen fixing bacteria available from a garden centre.

The seeds should take two or three weeks to germinate at 12 to 18 degrees centigrade (54 to 64°F).

Sweet pea should then be transplanted out following the last frost of spring at about 15 to 25 cm (6 to 10 inches) apart.

Caring for Sweet pea (Lathyrus)

Once growing keep the Sweet pea plants regularly watered and remove spent flower heads to promote additional flowers.

Lathyrus Growing and Care Guide

Common Names: Sweet Pea, Bitter Vetch, Everlasting Pea, Perennial Peavine. Pea: Yellow; Golden; Red; Silky beach; Nevada; Marsh; Leaf.
Life Cycle: Hardy annual. Hardy perennial.
Height: 20 to 120 inches (50 to 300 cm).
Native: Americas, Europe, Asia, Eastern Africa.
Growing Region: Annuals: zones 1 to 10. Perennials in zones 4 to 9.
Flowers: Annual: early spring, summer, autumn and winter. Perennial: spring and summer.
Flower Details: Red, white, blue, pink, purple, yellow. Asymmetric. Fragrant.
Foliage: Pinnate, feather-like. Tendrils.
Sow Outside:
Annuals: 1/2 inch (12 mm). Before last frost for summer blooms, or in autumn for winter blooms (warm areas only). Spacing: bush: 10 to 12 inches (25 to 30 cm); vines: 6 to 8 inches (15 to 20 cm).
Perennials: 1/4 inch. Before last frost or in autumn (warm areas only). Spacing 6 to 12 inches (15 to 30 cm).
Sow Inside: Requires some preparation: first chip seeds then apply a nitrogen-fixing bacteria. Use peat pots. Germination time: ten days to one month. Temperature 60°F (16°C). Seven or eight weeks in advance. Transplant outdoors following the last frost or in autumn.
Requirements: Full sunlight; perennials can also be grown in light shade. Dig in compost and bone meal to a depth of 16 inches (40cm) before sowing or transplanting. Good drainage. Soil pH 6 to 7. Provide support. Provide trellis. Use a mulch to keep soil cool and retain moisture. Regular watering during the growing season. Deadhead.
Family: Fabaceae.
Miscellaneous: Annual members of Lathyrus are very susceptible to disease so it is a good idea to employ a yearly rotation system. Perennials grow aggressively and can be difficult to remove from the garden.

Common Questions

What are the perennial members the Lathyrus genus?

The Lathyrus genus contains a number of perennial species. Notably among these are Lathyrus latifolius, the perennial pea. The exact number of perennial species is not known by me.

Do perennial members of Lathyrus make a good garden or landscaping plant?

Yes, perennial Lathyrus species can be attractive garden or landscaping plants. They typically have bright flowers and can provide a long-lasting display.

Which perennial Lathyrus species are most frequently grown by gardeners?

Among perennial species, Lathyrus latifolius (Perennial Pea or Everlasting Pea) is commonly grown for its attractive flowers and hardy nature.

Are perennial members of the Lathyrus plant genus fragrant?

Unlike their annual counterparts, many perennial Lathyrus species, including the Everlasting Pea, are not fragrant.

What is the perfect location to grow perennial Lathyrus?

Perennial Lathyrus plants prefer full sun to partial shade and well-drained soil. They can be grown on trellises or allowed to sprawl as ground cover.

Is perennial Lathyrus invasive in the USA, if so in which states?

Lathyrus latifolius (Perennial Pea) can become invasive in certain parts of the USA, particularly in the Northeast and along the Pacific coast.

How do I remove perennial Lathyrus plants from my garden?

To remove perennial Lathyrus, dig out the plant, making sure to remove all roots. Monitor the area for potential regrowth from missed roots.


The genus Lathyrus, part of the legume family Fabaceae, includes several perennial species known for their attractive, sweet-scented flowers and climbing nature. Notable among them are the evergreen perennial pea (Lathyrus latifolius) and the spring vetchling (Lathyrus vernus).

Perennial Lathyrus species prefer full sun to partial shade and fertile, well-drained soil. Planting can be done in spring or autumn, using seeds or division. It's important to provide a support structure for these climbers to grow on. Regular watering is essential, especially in dry periods, but take care not to waterlog the soil. Perennial species typically bloom in late spring or summer, offering vibrant splashes of color and inviting fragrant scents to the garden.

I hope that you enjoyed this guide on how to grow Lathyrus Sweet pea plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Wisteria sinensis, Kiwi Vine, and Baptisia plants.