Sweet Pea

The cool-season climbing annual grown for one thing above all - fragrance - in ruffled bicolor blooms on a vine that must be cut constantly to keep flowering. Beautiful, scented, and toxic to eat.

Soak or nick the hard seeds, sow in cool soil, give them a trellis, rich soil, and steady water - the key is to plant early and beat the heat.

Sweet peas begin with the seed. The hard-coated seeds germinate slowly and unevenly, so soak them 12-24 hours or nick the coat with a file before sowing an inch deep in cool soil (55-65°F). Timing is everything: sow as early as the ground can be worked in spring (a few weeks before the last frost — young plants take light frost), or, in mild-winter zones 7 and warmer, sow in fall so plants overwinter as small hardy seedlings for the biggest, earliest bloom. Many growers start seeds indoors in deep root-trainer pots to protect them from mice.

Set up a trellis, netting, or teepee before or at planting — sweet peas climb by tendrils and need something to grab from the start. Unlike lean-loving annuals, they want rich, well-drained soil, deep watering, and a light regular feed for the most and largest blooms. Pinch seedlings at 3-4 inches for strong, bushy plants. Give them full sun in cool climates, some afternoon shade where it's hot, and cool roots (mulch) — their real enemy is summer heat.

Keep them climbing, watered, and above all keep cutting - one seed pod and the plant stops blooming.

Three jobs define sweet pea care. Support: keep tucking and tying the fast-growing vines onto their trellis; cutting-flower growers train single stems up strings for extra-long blooms. Water: sweet peas are thirsty and hate dry roots — water deeply and mulch to keep the soil cool and moist, or the season ends early. And a light regular feed keeps them productive in the rich soil they like.

The most important habit is to cut relentlessly. Sweet peas are a strict cut-and-come-again flower: the instant a vine is allowed to form seed pods, it stops making flowers. Pick every stem as it opens (which conveniently is exactly what you want them for), and snip off any pods that slip past, and a plant will bloom for many weeks instead of a couple. Watch for aphids on the tips, and expect powdery mildew and thrips to arrive with the summer heat that signals the end of the run.

Cut long stems in the cool morning as the lowest flowers open, every couple of days, and never let a pod set.

Cutting sweet peas is both the reward and the essential maintenance. Harvest in the cool morning, choosing stems where the lowest flowers are just opening and the top buds are still tight — that gives the longest vase life. Cut long and often; a healthy vine produces stems every couple of days at its peak, and the scent of a fresh-cut bunch indoors is the whole point of growing them.

The cardinal rule bears repeating: do not let seed pods form if you want continued bloom. Every pod tells the plant its job is done. So cut every flower, deadhead any you can't use, and remove stray pods — and the plant keeps flowering right up until heat ends it. At the very end of the season, let a few pods dry on the vine for next year's seed, handling the toxic pods carefully and keeping them from children and pets.

Cut blooms last several days to a week in water; seed keeps for years - but it is toxic, so store it clearly labeled and out of reach.

Cut sweet peas last several days to about a week in clean, frequently changed water — recut the stems and keep them cool, and enjoy the fragrance while it lasts (it fades over a few days). They don't dry for everlasting arrangements; the pleasure is entirely in the fresh, scented bunch. There is no food use of any kind: the flowers are ornamental only.

The lasting product is seed, saved for replanting. Let end-of-season pods dry tan and papery on the vine, collect the round seeds, and store them cool, dark, and dry, where they stay viable three to five years. Because the seeds are toxic, label them clearly and store them well out of reach of children and pets — never with food or edible-pea seed.

Easy to save from dried pods, and it self-sows in mild climates - just handle and store the toxic seed safely.

Sweet pea seed is simple to save. Let some pods stay on the vine at the end of the season until they turn tan, dry, and papery (they may pop open and scatter, so watch them), then shell out the round, pea-like seeds and dry them another week. Store cool, dark, and dry — and clearly labeled as toxic, away from any edible seed — where they keep three to five years.

Old grandiflora heirlooms like 'Cupani' come true from seed; modern Spencer and F1 strains may vary somewhat in the next generation. In mild-winter climates sweet peas often self-sow, with fallen seed overwintering and sprouting on its own the following season. Soaking or nicking saved seed before resowing gives the most even germination, just as with bought seed.

Poor germination from hard seed, buds dropping from cold or heat, and an end-of-run of mildew and thrips as summer arrives.

Slow or patchy germination: the hard seed coat — soak 12-24 hours or nick before sowing, and use cool (not warm) soil. Vines grow but won't bloom, or buds drop off: usually temperature stress — a cold snap or, more often, the arrival of summer heat, which sweet peas can't take; also check they aren't dry at the roots. Flowering suddenly stops: the plant set seed pods — cut every bloom and remove all pods to restart it. White powdery leaves (powdery mildew): warm, dry, crowded, late-season conditions — improve airflow; it usually marks the end of the season. Streaked, distorted, silvery flowers (thrips): common in warm weather — the season is ending; cut hard. Seedlings sheared off: slugs and snails — patrol or bait. Seeds dug up: mice — start in pots or protect the row.

From a wild Sicilian flower sent to England in 1699 to the Edwardian 'queen of annuals' - the whole cutting industry traces to the heirloom 'Cupani'.

The sweet pea began as a modest, intensely fragrant wildflower from Sicily and southern Italy. In 1699 a Sicilian monk, Franciscus Cupani, sent seed of it to England (and to a botanist in Amsterdam), and that original bicolor maroon-and-violet flower — still grown today as 'Cupani' — is the ancestor of every sweet pea in cultivation. Prized above all for its scent, it spread through 18th- and 19th-century gardens as a cottage favorite.

Its golden age was the Edwardian era. Breeder Henry Eckford transformed the small grandiflora into larger 'grandiflora' strains, and in 1901 a chance mutation in the garden of Earl Spencer produced the big, ruffled, long-stemmed Spencer sweet pea — the form that made it the florist's flower and the 'queen of annuals'. A century of breeding for size and color came, as is often lamented, at some cost to the legendary fragrance, which is why scent-focused growers still return to the old grandifloras and 'Cupani'.

A cool-season flower defined by its hatred of heat: sow early or overwinter, and the growing zone decides whether it's a spring or winter crop.

Sweet peas live and die by temperature. Zones 3-6: a spring flower — sow as early as the soil can be worked (or start indoors) for bloom in early summer before the heat ends it; cool northern summers give the longest, best season. Zones 7-8: the classic overwintering approach shines — fall-sow so plants sit as small hardy seedlings through winter and explode into early, long-stemmed bloom in spring; heat-tolerant strains ('Old Spice', winter/early types) stretch the season a little further. Zones 9-10: strictly a cool-season crop — sow in late fall for winter-into-spring flowers, and accept that the plants finish as soon as real heat arrives. Everywhere the rule is the same: get them growing in cool weather, keep the roots cool and moist, and enjoy the rush before summer. They're fairly frost-tolerant as young plants but have no tolerance at all for a hot, dry summer.