Perennial sweet pea aka Lathyrus latifolius [LAY-thy-russ lat-ee-FOH-lee-us] is a rhizomatous herbaceous perennial. Known as:
- Perennial pea
- Wild sweet pea
- Everlasting pea
The plant is a member of the Fabaceae (fab-AY-see-ee) family and a native of the Mediterranean (northern Africa and southern Europe).
The genus name comes from the Greek word for pulse or pea Lathyrus. Its specific species latifolius means “broad-leaved.”
Perennial Sweet Pea Flower Care
Size & Growth
Perennial pea has a trailing and climbing habit and grows to a height of 6′ to 9′ feet with a spread of 3′ to 6′ feet.
When left to its own devices with nothing to climb, the plant will ramble as far as it can grow as a groundcover approximately 4″ to 8″ inches high. When it has support, it will climb to a height of 6′ to 9′ feet.
Flowering & Fragrance
Wild sweet pea blooms from June through September producing great masses of scentless blossoms. Its flowers are impressively showy in shades of white, pinkish purple and rose.
Even though the blossoms are scentless, they are attractive to butterflies, hummingbirds, bees, and other pollinators.
Wild sweet pea produces flowers in abundance throughout the summer and into the fall.
To encourage more blooms, be sure to deadhead spent flowers. If you don’t deadhead, the plant will produce seedpods which resemble those of an edible pea plant.
Take care not to eat these “peas,” though. They are quite poisonous. The plant’s leaves are broad, grayish green and about 3 inches long.
Light & Temperature
Sweet pea perennial is a hardy plant thriving in full sun in USDA hardiness zones 3 through 8.
While it can tolerate some light shade, it does best in full sun with night temperatures that do not fall below 50 degrees Fahrenheit during the growing season.
Watering & Feeding
It’s best to keep the soil evenly moist throughout the growing season. Use ground watering techniques (soaker hoses or drip irrigation) to avoid problems with fungal infection.
Fertilizer is not necessary if you amend the soil with ample amounts of compost and aged manure at planting time.
Once a sweet pea patch gets established, supplement the soil with a fertilizer high in potash. Avoid using high nitrogen fertilizer as this promotes excessive top growth.
Soil & Transplanting
It is easy to grow perennial pea in almost any kind of soil. The plants do quite well in soil of nearly every pH level. They seem not to mind clay, sand or loam.
The plant does best in average, well-draining soil with a moderate amount of moisture and humus. Amend with aged manure and compost.
Grooming & Maintenance
Vigorously cut perennial Lathyrus back to prevent it over growing and getting out of control. The pruning will encourage more bushy growth and more blossoms.
Deadhead flowers throughout the growing season to get more blooms. Stake the plant and or provide a trellis or other climbing structure as needed to prevent toppling over.
At the beginning of the growing season, in early spring, cut the plants all the way back to the ground. Next, remove dead growth from the plants climbing structure or trellis.
How To Propagate Perennial Lathyrus latifolius
Everlasting pea is both self-seeding and spreads via rhizomes, so propagation is quite easy.
Sow seed, in soil above 50°F. If you plan to have sweet peas climb, dig a trench about an inch deep and a foot away from the trellis, you intend the plant to climb.
Plant your seeds a couple of inches apart.
To encourage germination, crack the seed slightly using a toenail clipper or a file. Be careful not to cut too deeply, or you will damage the flower seed.
Provide a thorough watering at the time of planting. Water every two or three days after that. Be careful not to overdo it, but keep the soil moist. Seed should sprout within 3 to 4 weeks.
Thin the seedlings to a distance of about a foot apart.
Perennial Pea Pest or Disease Problems
This hardy, rambunctious plant has very few problems.
If kept in a damp setting with low air circulation and not enough sunlight, plants may experience problems with snails, slugs, fungal related problems such as:
- Leaf spot
- Black root rot
- Gray mold
To prevent these problems, choose a bright, airy location with well-draining soil for your sweet peas to dwell.
Avoid overwatering, and remember not to use a sprinkler or other overhead watering method.
The perennial pea is invasive, toxic and deer resistant.
Suggested Use For Perennial Pea
This showy, drought-resistant plant makes an excellent groundcover, but you must take care not to let it get away from you.
It can be quite invasive in many parts of the United States and Canada.
Everlasting sweet pea has been popular in North America since early in the 18th century and is said to been grown by Thomas Jefferson.
Since that time it has happily naturalized in some of the most challenging areas throughout Canada and the US.
It is not uncommon to see perennial peas growing with wild abandon in open fields, railroad right of ways, abandoned lots and along roadsides and fence rows.
When provided with sun, rain and the most minimum soil requirements, the perennial everlasting pea does very well as a ground cover or as a privacy screen when given lattice or other structures to climb.
It’s an excellent choice for covering embankments, slopes or unattractive rocky areas.
Perennial sweet pea makes a pretty and whimsical addition to cottage and border gardens and looks lovely tumbling over a fence or wall.
Individual plants also make excellent hanging basket candidates. Surprisingly, even though this is a vining plant the cut flower does quite well in arrangements.