Sweet peas are the most fragrant flower you can grow in a Zone 11 winter garden — and the most seasonal. Their delicate, butterfly-like flowers in pink, purple, white and blue, with a scent that fills a whole garden, are a cool-season treat. But sweet peas hate heat: they are a cool-climate annual, and in Zone 11 they only thrive in the coolest months, on a trellis where the air can move around them.
Grown at the right time, sweet peas are generous and long-flowering, and a fence covered in them is unforgettable. The planting calendar hub shows how Zone 11 timing works month by month, and our guide to when to plant pansies in Zone 11 covers another cool-season flower that shares sweet peas' love of mild weather.
Zone 11 at a glance
USDA Zone 11 covers the warmest, most tropical parts of the United States — Hawaii, southern Florida, Puerto Rico and the warmest coastal pockets. Winters are warm, with average winter lows of 40 to 50°F, and the growing season never really ends.
Zone 11 is frost-free year-round: there is no average last spring frost and no average first autumn frost. That means you plant by heat and by the wet and dry seasons, not by frost dates. These are USDA zone averages, not exact figures for any one garden — always check your local extension service and the forecast before planting.
| Detail | Zone 11 guidance |
|---|---|
| Average winter low | 40 to 50°F |
| Average last spring frost | Frost-free (no frost dates) |
| Average first autumn frost | Frost-free (no frost dates) |
| Days to germination | 7–14 days |
| Days to maturity | 60–70 days |
| Sowing | direct sow |
| Sun | full sun |
| Soil pH | 6.0–7.5 |
| Spacing | 6–8 inches |
| Water needs | moderate |
| Cold tolerance | hardy |
When to plant sweet peas in Zone 11
Plant sweet peas in Zone 11 in the coolest months, roughly November through February — this is the only window in which they thrive. Sow seed in late autumn so plants are climbing by the time the cool season arrives, and expect them to fade as the heat returns. Seed germinates in 7–14 days, and plants flower in 60–70 days, so an autumn sowing gives you blooms through the mild months. Do not try to grow sweet peas through a tropical summer: heat stops them flowering and invites disease. Zone 11 is frost-free, so there is no last frost date; check your local extension service and the forecast before sowing.
Starting sweet peas in Zone 11
Start sweet peas from seed sown directly where they are to flower, beside a trellis, fence or netting they can climb — sweet peas are climbers and need support from the start. Soak the seed overnight to speed germination, then sow it about an inch deep. Space plants 6–8 inches apart along the support, and give them a spot with morning sun and afternoon shade. Pinch out the growing tip when plants are a few inches tall to encourage branching and more flowers. The seed-starting calculator can work out your sowing dates.
Soil, spacing, sun and water
Sweet peas need full sun in cool climates, but in Zone 11 give them morning sun and afternoon shade, and rich, fertile, well-drained soil with a pH of 6.0–7.5. Dig in plenty of compost before sowing — sweet peas are hungry feeders — and mulch to keep the roots cool. Water needs are moderate: water regularly, especially in dry spells, keeping the leaves dry, because wet leaves in humid weather invite mildew. Feed every two weeks with a balanced liquid feed while they are flowering.
Companion planting
Good companions for sweet peas include lavender, marigolds, garlic and chives. Marigolds planted nearby deter soil pests, while lavender draws in the bees that visit sweet pea flowers. Sweet peas fix nitrogen in the soil, which benefits the plants that follow them. Keep sweet peas away from onions and garlic in the same bed if you grow vegetables, as they can stunt each other. The companion planting finder can suggest combinations for your whole garden.
Pests and problems
The common pests to watch for with sweet peas are aphids, bean beetles, slugs and cutworms. Aphids cluster on young shoots and buds — wash them off with a strong jet of water. Slugs and snails chew seedlings at night in the wet season; protect young plants with a ring of coarse grit. Powdery mildew is the bigger threat in humid Zone 11 — space plants for airflow, water at the base, and remove affected leaves at once. If you are unsure what is damaging a plant, the pest identifier helper can narrow it down.
Harvest and storage
Harvest sweet peas 60–70 days after sowing, when the first flowers open. Cut sweet peas in the morning, when they are fresh, cutting the stem long, and they will last several days in a vase — and the more you cut, the more they flower, so pick often. Deadhead spent blooms every few days and the plants will keep flowering through the cool season instead of setting seed. Pick flowers in the morning, when their scent is strongest. At the end of the cool season, compost the plants as the heat returns.
Growing sweet peas up a trellis in Zone 11
Sweet peas need support from the day they sprout, and in Zone 11 the support matters more than usual: a trellis in open air gives the plants the airflow they need to stay healthy in humid weather. Use a fence, a bamboo wigwam or a netting panel, and tie the young stems in loosely as they climb — sweet peas climb with tendrils, but they need a little help to find the support. Give them morning sun and afternoon shade, keep the roots cool with mulch, and water at the base. A trellis covered in sweet peas, with their scent drifting across the garden on a cool tropical evening, is one of the great pleasures of a Zone 11 winter garden.
Frequently asked questions
When should I plant sweet peas in Zone 11?
Plant in the coolest months, roughly November through February — this is the only window in which sweet peas thrive in the tropics. Seed germinates in 7–14 days and plants flower in 60–70 days.
Can sweet peas survive summer in Zone 11?
No — tropical summer heat stops them flowering and usually kills them. Treat sweet peas as a cool-season crop and replant each autumn.
Are sweet pea flowers edible?
No — sweet pea flowers and seeds are poisonous, unlike garden peas. Do not eat them, and keep them away from children and pets.
How do I get more sweet pea flowers?
Pick often — the more you cut, the more they flower. Deadhead spent blooms every few days, and pinch out the growing tip when plants are young to encourage branching.