Sweet pea

Sun

Full sun; light afternoon shade helps in warm climates.

Water

Keep the root zone evenly moist, especially during flowering. Water deeply when the soil surface begins to dry, without leaving the soil waterlogged.

Soil

Fertile, well-drained soil enriched with compost, preferably neutral to slightly alkaline.

Height

5-8 ft (1.5-2.4 m); dwarf varieties are much shorter.

Spread

1-2 ft (0.3-0.6 m)

Flowers

Spring to early summer, continuing into summer where conditions stay cool; autumn-sown plants may flower in winter in mild climates. Flowers come in white, cream, pink, red, purple, blue shades and bicolours; fragrance varies by variety.

Foliage

Soft green leaves with paired oval leaflets and branching tendrils that grip narrow supports.

Growth

Fast in cool spring weather.

Care needed

Medium

• Install netting, a trellis or twiggy supports at planting, and tie in young shoots until their tendrils take hold.
• Water deeply during dry spells; plants in pots may need checking daily.
• Mulch around established plants to keep roots cool and moist, leaving space around the stems.
• In reasonably fertile soil, avoid heavy nitrogen feeding; feed container plants regularly with a flowering-plant fertiliser according to the label.
• Pick flowers frequently and remove developing pods to prolong flowering.

Pruning. Pinch out the growing tip once seedlings have three or four pairs of leaves to encourage branching. During flowering, cut stems just above a leaf joint and remove faded flowers before pods develop.

Autumn

In mild-winter areas, sow into deep pots or prepared ground for earlier flowers; protect seedlings from slugs and severe frost.

Late winter

In cold-winter areas, sow into deep pots in a bright, cool, frost-free place, roughly six weeks before planting outdoors.

Early spring

Harden off indoor-raised seedlings and plant when the soil is workable and severe freezes have passed. Direct-sow where the growing season allows.

Spring

Set up supports, guide shoots onto them and mulch once the soil has warmed.

Spring to summer

Water consistently, cut flowers often and remove pods. In mild Australian climates, autumn-sown plants may need this care from winter onward.

Late summer

Remove plants once heat or age ends flowering. If saving seed, leave a few healthy pods to turn brown and dry before collecting.

• Train over hazel or bamboo wigwams in cottage borders for scented vertical colour.
• Grow along netting in a cutting garden, with access on both sides for picking.
• Use a narrow trellis beside a path or seating area where the fragrance can be enjoyed.
• Plant dwarf varieties in deep containers for colour on a sunny patio.

Garden styles it suits: Cottage garden, English country, Romantic rose garden, Sensory garden, Traditional and Pastel border.

Plant it with: Calendula, Cornflower, Love-in-a-mist, Snapdragon, Sweet alyssum and Lady's mantle.

Wildlife: Some bees, particularly bumblebees, visit the flowers, although access and value vary with flower form. Dense growth provides temporary shelter for small garden invertebrates.

• Slugs and snails eat seedlings: inspect after dark, remove pests and use wildlife-conscious slug control where needed.
• Aphids cluster on shoot tips and can spread viruses: wash off small colonies with water and remove badly distorted, mottled plants.
• Powdery mildew coats leaves in dry or crowded conditions: keep roots evenly moist, improve airflow and remove badly affected foliage.
• Bud drop or poor flowering follows heat, drought or sudden changes in conditions: maintain steady moisture, avoid excess nitrogen and grow through the cooler part of the year.

Toxic to people, cats, dogs and horses if eaten, especially the seeds and pods. Other plant parts should also be treated as unsafe to eat. Large or repeated ingestion can cause serious neurological illness called lathyrism; keep seeds away from children and pets, and do not feed plants to livestock.

• Perennial sweet pea (Lathyrus latifolius)

  A vigorous perennial with broad, winged stems and usually unscented pink, white or rose flowers; it returns from the same rootstock each year.

• Garden pea (Pisum sativum)

  Usually has much larger, leaf-like stipules clasping the stems and less showy flowers. Do not identify edible peas from flower colour alone; only eat plants grown from a known edible pea variety.

• Everlasting pea (Lathyrus sylvestris)

  A perennial with narrow leaflets, winged stems and smaller, generally unscented pinkish flowers, rather than the large, often strongly scented flowers of annual sweet pea.

Lathyrus comes from an ancient Greek name for a leguminous plant, while odoratus means fragrant, referring to the flowers.

Propagation. Grow from seed, sowing in autumn where winters are mild or in late winter to early spring elsewhere. Sow about 0.5-1 in (1-2.5 cm) deep in deep pots or directly into prepared soil. If a hard seed fails to swell, lightly nick the coat away from the seed's scar before sowing.

Accepted botanical name

Lathyrus odoratus

In the US and Canada

Introduced in the lower 48 states.

Native range

Italy and Sicilia.

Measured

Average height 46 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.