Sweet peas fill my house with more than just scent – they evoke memories of the past. My grandfather tended these climbing annuals every summer until the end of his life, and so did a special neighbour, who took pride in passing fistfuls of cherished seed over the back fence at the end of the season.
The fragrant and sun-loving sweet pea (Lathyrus odoratus) comes in a riot of colours – both solid and variegated – and ranges in height from a dwarf 15 centimetres to tall climbers that can reach up to three metres in height. The perennial sweet pea (Lathyrus latifolius) is its rough-and-tumble cousin, a climbing vine that grows with little care and often becomes naturalized (some would say weedy). The latter produces small, faintly scented blooms in purplish-rose, red, white, blue or yellow.
Being members of the pea family, annual sweet peas appreciate cooler temperatures, full morning sun and afternoon shade. With the exception of bush varieties, most require an arbour, fence or twig teepee to climb through. Their tendrils are fine; in some cases they may need trellising in order to “grab” on. It’s best to put supports in place before you seed to minimize root disturbance.
Sweet peas thrive in loose, rich, alkaline soil. Before planting, dig down at least 30 centimetres and add generous amounts of compost, leaf mould or well-rotted manure. If your soil is acidic, add lime to make it more alkaline. An average-sized handful is enough for an 8 by 10 garden bed.
Seeds sprout best under cool, moist conditions. Damp soil is fine; wet, waterlogged soil is not – it may cause seeds to rot.
Direct sow seeds in early spring. Bury seeds 2.5 centimetres deep and space them eight to 10 centimetres apart. Water well, but don’t drown the soil. On the coast, seeds may go into the ground as early as February, but colder parts of B.C. will have to wait for the ground to thaw. The seeds can tolerate light frosts.
Some sweet pea aficionados start seeds indoors, about six to eight weeks before planting out. Use a blend of topsoil, peat moss and compost and put the containers in a cool, bright location. Once they sprout, keep the seedlings cool and moist, and ensure they get plenty of light. Germination takes six to14 days; most varieties flower about 90 days after they sprout.
Sweet peas can occasionally be difficult to germinate. Some gardeners slip seeds between moistened paper towels to encourage sprouting, while others soak seeds overnight in warm water or stratify (chip) them to get them going. A word of caution about chipping: some of the mottled and black-seeded varieties benefit from this but white, brown and wrinkle-seeded varieties should never be chipped or they’ll inevitably rot.
If your soil is healthy, sweet peas will thrive without fertilizer, though a monthly dose of manure tea or fish fertilizer will encourage them to bloom. Water deeply (at least 2.5 centimetres) once or twice a week – more often if the weather is hot. Three to five centimetres of grass clippings around the base of the plants will help retain moisture. Any more, however, and you’ll encourage rot and pests.
Slugs are the most persistent pests. Deterrents include copper stripping around young shoots, crushed eggshells on the nearby ground or sacrificial saucers of beer. Hand-picking at dusk is also surprisingly effective.
Sweet peas can also be troubled by aphids, which can spread mould or the pea virus. Discourage aphids with repeated strong blasts from the garden hose. The pea virus, which is extremely rare, shows up as a distinct white striping on the leaves. Infected plants should be destroyed. More common is white mould, which can be treated with a sulphur spray.
One of the nicest things about sweet peas is that the more you pick, the more they’ll produce. If seed pods form, the plant begins to shut down. Harvest sweet peas when the first blooms on a stem are open; the rest will open in the vase. Harvested regularly, sweet peas should last in the garden for at least a month, but as the plant ages, the flower stems will shorten.
Laura Langston is a writer and gardener who grows masses of sweet peas in her Victoria garden.