How to Grow Sweet Peas
Lathyrus odoratus
Old-fashioned climbing annuals with intensely fragrant, ruffled blooms.
By the Plants by Zone Editorial Team · Reviewed June 1, 2026
About sweet peas
Sweet peas are cool-season climbing annuals beloved for their heady fragrance and delicate, ruffled flowers in soft pastels. They thrive in the cool of spring, climbing a trellis with tendrils, and bloom most generously when picked often. Note: despite the name, the seeds and pods are toxic and not edible.
When to plant and harvest sweet peas
Timing is relative to your frost dates. Find your USDA zone for exact dates, or browse the month-by-month calendars.
Start seeds indoors
6–8 weeks before last frost
Transplant outdoors
A few weeks before last frost (frost-tolerant)
Direct sow
As soon as soil can be worked in early spring
Harvest
Late spring into summer
How to grow sweet peas step by step
- 1
Soak seeds overnight, then sow early — sweet peas love cool soil and resent heat.
- 2
Provide a trellis, netting, or strings at planting time for the tendrils to climb.
- 3
Pinch seedlings above the third leaf pair to encourage bushy, branching growth.
- 4
Keep the roots cool and evenly moist, and mulch the base.
- 5
Pick flowers every few days — the more you cut, the longer they bloom.
- 6
Expect them to fade in summer heat; pull and replace with a warm-season climber.
Common problems growing sweet peas
⚠ Few flowers, then quick decline
Heat ends the show and seed pods stop it — sow early, keep roots cool, and pick blooms constantly before pods form.
⚠ Leggy, non-branching plants
Pinch young plants to force side shoots and more flowering stems.
⚠ Poor or slow germination
Soak seeds overnight before sowing, and start in cool (not cold, not warm) soil.
✓ Good companions for sweet peas
✗ Keep away from
🧺 Harvesting sweet peas
Cut sweet peas when the lowest one or two florets on a stem are open and pick every two or three days — frequent harvesting and deadheading is the secret to weeks of bloom, since any seed pods that form signal the plant to stop. Bring them indoors for the fragrance.
Sweet Peas: frequently asked questions
Are sweet peas edible like garden peas?＋
No — sweet peas are ornamental only. Their seeds and pods are toxic, so they should never be eaten; grow regular peas for the kitchen.
When do I plant sweet peas?＋
Very early — they’re cool-season plants. Sow as soon as the soil can be worked in spring (or in fall in mild-winter zones), since they fade in summer heat.
Grow sweet peas in your zone
See exactly when to plant and what else to grow alongside sweet peas, tailored to your USDA hardiness zone.
