How To Grow And Care For Sweet Pea Flowers

Ornamental sweet peas (Lathyrus odoratus) have been around for centuries, long enough to be considered old-fashioned, but these delicate-looking flowers are still popular. Sweet peas are climbing vines with curling tendrils and clusters of dainty flowers. Look for them in crimson, apricot, violet, rose, white, pink, blue, and other colors. Some gardeners think they smell like orange blossoms, honey, and jasmine. Others say they have a grapelike scent. Let them twine over an arbor, spill out window boxes, or delight as clippings in bouquets. Sweet peas are deer-resistant, but butterflies and bees love them. Some areas in North America consider this flower to be invasive. Additionally, all parts of sweet peas are toxic to pets and people.

Plant Attributes

Common Name:	Sweet Pea, Perennial Pea, Everlasting Pea
Botanical Name:	Lathyrus odoratus
Family	Fabaceae
Plant Type:	Annual, Vine
Mature Size:	5-8 ft. tall
Sun Exposure:	Full, Partial
Soil Type:	Moist but Well-drained, Loamy
Soil pH:	Alkaline (7.0 to 7.5)
Bloom Time:	Summer, Fall
Flower Color:	Red, Pink, Orange, Blue, Purple, White
Hardiness Zones:	Zones 3-8 (USDA)
Native Area:	Europe, Mediterranean
Toxicity:	toxic to pets, toxic to people

Sweet Peas Care

Sweet peas are easy-to-grow, hardy annuals. If you live in USDA Zone 7 or warmer, plant them outdoors in late fall. Elsewhere, grow them from late winter to very early spring. The seedlings can survive a light frost. The climbing nature of this plant makes it invasive in some areas.

Light

Sweet pea flowers thrive in full sunlight. In areas with hot, humid summers, sweet pea flowers benefit from partial afternoon sunlight. In particular, Southern gardeners should grow sweet peas in an area that provides enough afternoon shade, so the flowers don't wilt.

Soil

Sweet peas need well-draining, humus-rich soil with a neutral to alkaline pH. Mix in compost to amend your soil, if required. For best results, amend the soil in the fall before planting. Support sweet peas in the garden with netting, twine, or anchored trellises so the fast-growing vines won't pull them down.

Water

Water regularly if rainfall isn't sufficient. Keep the soil moist during the growing season. Check to see if the soil is moist with your fingers by reaching an inch into the ground or container.

Temperature and Humidity

Sweet peas thrive when planted after the last frost in the winter. While seedlings tolerate a light frost, a mild and moderate temperature is best for this plant. Extreme hot, humid temperatures and frigid climates will harm a sweet pea's growing potential.

Fertilizer

Mulch sweet peas to help hold moisture in the soil and keep their roots cool. Fertilize with a liquid fertilizer every couple of weeks or as directed on your product's label, especially during the growing season. Blood meal can also help to increase a sweet pea's longevity so that you can propagate the plant through cuttings.

Types of Sweet Peas

• 'Henry Eckford': This heirloom with orange-red salmon flowers dates to 1904.
• 'Old Spice': Choose this mix of colors for its honey and orange blossom perfume.
• 'Cupani's Original': Sweet peas like cool weather, but some tolerate more heat than others, like this purple and blue bicolor.
• 'Strawberry Sundae': Highly fragrant flowers in pastel pink, rose, and white.
• 'Flora Norton': These soft blue flowers are wonderful for cutting. Vines grow to six feet.
• 'Bijou Mix': These short, bushy sweet peas mix lavender, pink, purple, blue, and white.
• 'Sugar and Spice': Enjoy these solid and bicolored blooms held on dwarf plants in hanging baskets. At seven inches tall and wide, they don't need pinching.
• 'Cupid Pink': White and pink bicolored flowers bloom on this dwarf plant.

Pruning

Other than pinching, sweet peas don't need much pruning. Deadhead them often and remove dead or dying leaves. Sweet pea vines die naturally when the temperatures rise. Pull and compost them if they're not diseased or infested with pests.

If your sweet pea plant is too tall, cut off the top of the primary vine just above a shoot or bud.

Propagating Sweet Peas

One easy way to propagate sweet peas is from cuttings. For best results, take cuttings to plant in early summer before the temperatures rise too much.

• Start by using young sweet pea seedlings to take cuttings. The side shoots will replace the cuttings. 
• Use a sharp knife or scissors to cut part of the stem above the leaves, usually around five inches tall. 
• Dip the stems into a rooting hormone solution, then move the cutting to a water container. Place the container in partial sunlight. 
• You should see new roots growing in about two weeks. Once the roots establish, move the plant into a container filled with potting soil. 
• After moving the container to indirect sunlight, continue watering for about six weeks until the cuttings have more developed roots to transplant outside.
  

How to Grow Sweet Peas From Seed

Indoors, sow sweet pea seeds four to six weeks before your average last frost. Some can take a long time to germinate. Soak them overnight in water to soften their hard seed coats, or scuff them with sandpaper. Then plant two or three seeds per pot in biodegradable pots of fresh potting mix. Cover the containers with clear plastic bags to create mini-greenhouses and keep them in a cool, bright spot in your house. When the seedlings are up, remove all but one in each pot. Two weeks before the last spring frost, transplant the pots directly into the garden or outdoor containers so you won't disturb the long tap roots.

Pinch the growing tips when the seedlings are about four inches tall, so they'll form side shoots. Plant them in rows, six to eight inches apart, in a spot with partial sun. You should see blooms four to six weeks after the vines start growing.

Potting and Repotting Sweet Peas

Sweet peas, when grown in containers, also need something to climb. Choose short varieties so you won't need tall supports, and containers at least six inches deep filled with good potting mix. Pinch the seedlings' growing tips when they're four inches tall. Otherwise, caring for sweet peas in containers is the same as caring for sweet peas outdoors, although you may need to water them more often.

Overwintering

While sweet peas are relatively cold-hardy, there are ways to protect plants during the winter. Move sweet peas indoors when temperatures drop below freezing when planted in containers. In the late winter, prune dead or diseased leaves and flowers to the ground to make room for new growth. To help protect the plant's roots, cover them with burlap or bubble wrap.

Common Pests & Plant Diseases

Pests like aphids, leaf miners, spider mites, and thrips can attack sweet peas. Slugs and snails also pose a risk to sweet peas. Try knocking off pests with a strong stream of water from your hose. Keep sweet peas weeded, so pests can't hide nearby. When possible, spray with insecticidal soap or neem oil to eliminate pests, rather than chemicals. Use snail or slug baits or traps.

Possible diseases include downy mildew, leaf spot, rust, virus diseases, root and crown rot, and rust. Remove heavily infested or diseased foliage to keep problems from spreading. Help prevent diseases and rotting by giving plants good air circulation—water with drip irrigation or soaker hoses to keep foliage dry. If diseases persist, look for a fungicide labeled for your specific problem.

How to Get Sweet Peas to Bloom

During late spring and early summer, sweet peas bloom faster. To help increase the flower's bloom size and longevity, use compost or dried aged manure. Fertilizers with higher phosphorus than nitrogen will also improve flower production.

Common Problems With Sweet Peas

Bud Drop

Sweet peas sometimes drop their buds when they get too dry or nighttime temperatures are below 30 degrees Fahrenheit. Cut off buds that threaten to drop at the base of their stems so the plants can keep growing. Overfertilizing can also cause bud drop. Stop feeding until the flowers open entirely.

Not Enough Buds

Too much nitrogen can promote leaves instead of flowers. Switch to a tomato fertilizer if your product seems to contain too much.