Sweet peas are one of the most popular annual flowering vines grown in gardens. Their beautiful and fragrant blooms last throughout the summer, making them a favorite for cut flowers. But are sweet pea plants actually perennials?
What are Sweet Peas?
Sweet peas (Lathyrus odoratus) are flowering vines in the Fabaceae or pea family. They are native to Sicily and grown as ornamental plants for their brightly colored, fragrant blooms.
There are over 500 varieties of sweet peas available, with flowers that come in many colors like white, pink, purple, red, orange, yellow and bi-colors. The blooms grow on long stems, making them excellent for cut flowers.
Sweet peas grow best in cool, moist climates. They can reach heights of 6-10 feet when supported by trellises or other structures. The vines produce tendrils that wrap around supports as they grow upward.
Are Sweet Peas Annuals or Perennials?
Sweet peas are annual plants, meaning they complete their entire lifecycle in one growing season. Annuals germinate, grow, flower, set seed and die all within a single year.
Here are some key facts about the lifecycle of sweet peas
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They are planted by seed in spring after the last frost date.
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The vines grow quickly and begin flowering in early summer.
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With proper care sweet peas will continue blooming all summer long.
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By late summer or fall, the plants start to decline as temperatures cool.
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The vines completely die off with the first hard frost.
So while sweet peas may self-seed and come back the following year, the plants themselves are not perennial. The new plants growing from self-sown seeds start the annual cycle over again.
Perennial plants, on the other hand, persist for many years. Their top growth dies back in winter but the root system survives to regenerate new growth the following spring. Popular perennial vines include clematis, honeysuckle and grapevine.
Can Sweet Peas Be Grown as Perennials?
While classified as annuals, there are a few techniques that allow you to grow sweet peas as short-lived perennials:
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Plant heirloom or perpetual flowering varieties that bloom later and longer. Many will continue flowering until frost if deadheaded.
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Provide protection from freezing temperatures, like an unheated greenhouse or cold frame. This prevents the vines from being killed off in winter.
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Mulch heavily around the roots for insulation and leave some foliage on the vines over winter.
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In very mild winter climates (Zone 9-10), sweet peas may survive outdoors if cut back and mulched after blooming finishes.
However, most gardeners find it’s easier to simply replant fast-growing sweet peas each year for the longest season of flowers. With proper care, annual sweet peas will provide months of fragrant, colorful blooms to enjoy.
Lathyrus latifolius (Everlasting Pea)
| Also known as: | Perennial Pea, Sweet Pea |
|---|---|
| Genus: | Lathyrus |
| Family: | Fabaceae (Pea) |
| Life cycle: | perennial |
| Origin: | Europe |
| Status: |
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| Habitat: | part shade, sun; disturbed soil; roadsides, woodland edges, fields, gardens |
| Bloom season: | July – September |
| Plant height: | 1 to 6 foot vine |
| Wetland Indicator Status: | none |
| MN county distribution (click map to enlarge): | |
| National distribution (click map to enlarge): |
Pick an for a larger view. See the glossary for icon descriptions.
Note: it was brought to our attention that the s on this page are more indicative of Lathyrus sylvestris than L. latifolius . After some study, we agree. We were not previously aware that L. sylvestris was present in Minnesota but it obviously is.
Clusters of 5 to 15 stalked flowers on stems arising from the leaf axils. Flowers are pea-shaped, the 2 upper petals broad and erect, forming a semi-circle over the lower petals. Flower color is typically deep pink, but may be white or purplish. The calyx holding the flower is bell-shaped, about ¼ inch long, with 5 teeth of equal size.
Leaves are compound with a single pair of leaflets on a winged stalk and a branched tendril between them. Leaflets are 1 to 3 inches long, lance-elliptic to linear, pointed at the tip, toothless and hairless. The pair of leafy appendages (stipules) attached to the stem at the leaf base have 2 lobes, lance to egg-shaped, in outline shaped like half of an arrowhead. Stems are 4 sided and strongly winged, variously hairy to smooth.
Fruit is a somewhat flattened pea pod about 2 inches long. The pod dries to brown.
Not well documented in Minnesota, reports from other parts of the country indicate Everlasting Pea is not an especially aggressive species compared to other non-native members of the pea family, but the fact that the population we found was along a disturbed roadside indicates it is quite capable of moving itself around. The broad upper petals resemble those of one the Strophostyles species but the horn-like projections of those species are absent from Everlasting Pea. Besides the flowers, it can be distinguished from other peas by the leaves compound in 2s with a branched tendril between the leaflet pairs.
Sweet Peas 101: Growing the most fragrant flower (without seed trays!)
FAQ
Do sweet peas come back every year?
Most sweet pea varieties are annuals and need to be replanted each year.
Which sweet peas are perennial?
Lathyrus latifolius (Perennial Sweet Pea) Award-winner Lathyrus latifolius, commonly known as Everlasting Pea or Perennial Sweet Pea is a vigorous climbing perennial that produces racemes of 5-11 vibrant rose to white pea-like flowers, 1 in. across (2.5 cm).
Does sweet pea survive winter?
When to Sow Sweet Pea Seeds: If you live in a mild climate, you may be able to fall-plant and overwinter your sweet pea crop. In Zone 5b where I grow, it’s simply too cold for sweet peas to survive our entire winter season- so I start my seeds in the very early spring.
What is the lifespan of a sweet pea?
Sweet peas are a short-lived cut flower, lasting at best 4 to 5 days in a vase.