Sweet peas are mostly annual climbing superstars. Once that first autumn frost hits, the plants usually call it quits for the season. But don’t worry! You can ensure your garden is bursting with those colorful, butterfly-like blooms again next year just by saving the seeds. All it takes is harvesting the little grains at the right time and knowing the best way to plant them.
Harvesting Seeds from Your Own Plants
The sweet pea blooming season kicks off in June and can last well into late fall. You’ll usually see a mix of closed buds, full blooms, and faded flowers all on the same plant. Normally, you’d want to deadhead those spent flowers quickly so the plant doesn’t waste energy making seeds. However, for a seed harvest, just leave a few flowers alone starting in late summer.
- After the flowers fade, long, flat pods will form.
- Each pod holds about eight developing seeds.
- Wait until the pods are completely dried out.
- If they pop open with a little bit of finger pressure, the seeds are ready.
- Remove the seeds from the pods.
- Let them dry indoors on a paper towel for a few days.
- Store them in a paper envelope.
- Keep them in a cool, dark, and dry spot until you’re ready to plant.
Pro Tip:
Make sure to harvest all the ripe pods! If you leave them on the vine, they’ll eventually burst and self-seed. Since sweet peas grow so vigorously, they can quickly turn into weeds if they start popping up everywhere on their own.
Buying Seeds
If you don’t have sweet peas in your garden yet—or if you’re looking for a specific new color—you can easily find seeds at the store. While supermarkets usually carry a few basic varieties at a good price, you’ll find the really unique and fancy cultivars at garden centers or online shops.
Sowing Seeds Outdoors
Sweet peas aren’t hardy enough to handle a freeze, so wait until late April or mid-May to sow them directly outside. The good news is they germinate fast and quickly transform into climbing plants that can reach up to 6 feet tall.
- Loosen the soil well before planting.
- Planting depth: about 1/2 inch.
- Spacing: 4 inches apart.
- Sow two seeds together at each spot.
- Keep the soil moist using a gentle spray setting on your hose.
- Protect the seeds from hungry birds with a fine mesh net.
Starting Seeds Indoors
If you want to give your sweet peas a head start or grow extra-strong plants, try starting them indoors in early February. You’ll need a bright spot that isn’t in direct, scorching sunlight, with temperatures between 60°F and 65°F.
- Use a high-quality seed-starting mix.
- Space seeds about an inch apart.
- Cover with a 1/2-inch layer of soil.
- Water gently with a spray bottle.
- Cover the tray with a clear plastic bag to hold in moisture (but open it daily for fresh air).
- Once they hit 4 inches tall, give them some support with thin wooden skewers or sticks.
Around mid-May, once the threat of frost has passed, you can transplant your young starts into the garden bed.
