Sweet peas are prolific climbers that grow incredibly fast. With just one packet of seeds, you can turn a bare corner of your garden into a lush, colorful oasis in just a few weeks. But don’t just poke a few seeds into the dirt and hope for the best—there’s a little more to it if you want that “wow” factor!
Starting Your Young Plants
You’ll find sweet peas as perennials, like the edible vetch. However, the real garden favorites are fragrant sweet peas (Lathyrus odoratus), which are grown from seeds. These beauties are actually legumes, and unlike their perennial cousins, they aren’t frost-hardy. That means you’ll need to sow them fresh every year. You can buy seeds at any garden center or harvest them from your own plants in the fall.
Pro Tip:
Harvest all the ripe seeds you can find, even if you don’t need them all. If you leave them, the plant will self-seed and can quickly turn into a weed problem next season.
Sowing: Timing and Technique
If you’re sowing directly outdoors, wait until at least late April. They’ll still have plenty of time to grow into massive climbers. But if you’re like me and can’t wait to get started, you can start seeds indoors as early as February.
- Soak seeds overnight to help them sprout.
- Use a good seed-starting mix.
- Space seeds about an inch (3 cm) apart.
- Plant them about half an inch (1 cm) deep.
- Keep the soil moist; a plastic bag over the pot helps create a mini-greenhouse effect.
- Keep them at 60-65°F (15-18°C) for germination.
- Provide support once they hit about 4 inches (10 cm) tall.
Pro Tip:
If you sow directly into the garden bed, watch out for hungry birds! They love to snack on the seeds. Cover your planting area with a fine mesh net until they get established.
Planting Time
Whether you started them yourself or picked up some starts at the nursery, wait until mid-May to put them in the ground—basically, once the danger of frost has passed. Sweet peas do great in garden beds, but they’re also happy in large containers.
Location and Soil
This climbing plant is a sun-worshipper. To get the most blooms, pick a sunny spot that’s also protected from the wind so those delicate vines don’t get thrashed around. They prefer soil that is rich in organic matter (humus) and slightly alkaline (a little lime goes a long way).
Giving Them a Lift
Sweet peas need a sturdy trellis to reach for the sky. However, keep in mind that their thin little tendrils need something narrow to grab onto. Chain-link fences are perfect; thick wooden privacy fences, not so much. You can use a store-bought obelisk or build your own DIY trellis, just make sure it’s at least 5 feet (1.5 m) tall.
Care and Maintenance
On warm days, you’ve got to stay on top of watering. All that foliage means they lose moisture fast! A layer of mulch helps keep the roots cool and moist while adding nutrients. Since they have a long blooming season (from June through October), they’re heavy feeders—regular fertilizing is key to keeping those flowers coming.
Don’t be afraid to cut the flowers for a vase! In fact, the more you cut, the more they bloom. For perennial varieties, a light pruning can help encourage a bushier shape.
Winterizing
Annual sweet peas won’t survive the winter, so just pull them out and compost them at the end of the season. If you have the perennial variety, they are quite hardy. Leave the old foliage on until spring (it acts as a natural winter coat) and then cut it back to about 4 inches (10 cm) above the ground. In really cold regions, a little extra brush or mulch over the base doesn’t hurt!
