Sweet peas are grown for one thing above all: scent. Their flowers in pink, purple, white and blue carry a fragrance no other annual can match, and a vase of sweet peas can perfume a whole room. In Zone 13, though, they are a cool-season flower, and with winter lows above 60°F and no frost at all, the zone never gives them the cool weather they love. The answer is to grow them in the coolest months and accept a short, glorious season.
That season is well worth having. Sweet peas climb a trellis, fence or obelisk, need little space for the flowers they give, and flower more the more you pick them. Planted at the right time, with rich soil and steady moisture, they flower for weeks. This guide covers when to plant sweet peas in Zone 13, with the soil, spacing, sun, water and care they need. Use the Zone 13 planting calendar to see what else to sow alongside it.
Zone 13 at a glance
USDA Zone 13 has average winter lows of above 60°F and is frost-free year-round — there is no last or first frost date to plan around. Plan by heat and by the wet and dry seasons instead: heat lovers grow year-round, while cool-season crops only succeed in the coolest months. These are zone averages, not promises for any one garden, so check your local extension service for your area.
| Detail | Zone 13 guidance |
|---|---|
| Last / first frost | None — Zone 13 is frost-free year-round |
| Average winter low | above 60°F |
| Days to germination | 7–14 days |
| Days to maturity | 60–70 days |
| Sowing | Direct sow |
| Transplanting / planting out | Coolest months only; best results in the planting window above |
| Harvest | Flowers 60–70 days after sowing/planting; pick regularly |
| Sun | full sun |
| Soil pH | 6.0–7.5 |
| Spacing | 6–8 inches |
| Water needs | moderate |
When to plant sweet peas in Zone 13
In Zone 13, plant sweet peas in the coolest months, roughly November to February, when nights are at their mildest. There is no last or first frost date to plan around — Zone 13 is frost-free year-round with winter lows above 60°F — so work from the calendar and the cool season instead. Sow seed in the months before that window so seedlings are ready to set out as the coolest weather arrives, or sow direct in the bed in November. A planting made in the hot season will struggle: plants stretch, flower sparsely and are quickly finished by heat. Sweet peas take 60–70 days to maturity, so a November sowing can flower in the cool season. Check your local extension service for the best planting windows in your area. Frost dates are zone averages — check your local extension service before you commit to a date.
Keep a note of your sowing date and first flowers; after one season you will know exactly which weeks suit sweet peas best in your own garden. Succession sow a second batch a few weeks after the first to stretch the display, but do not sow after the cool season has passed — late plants rarely flower well before the heat arrives. Sweet peas are annuals, so plan to sow fresh seed each cool season.
Starting sweet peas in Zone 13
Sweet peas are direct sown in Zone 13, and they do best sown where they are to grow. Soak the large seeds overnight, then sow them in the bed, cover lightly, and keep the soil moist until seedlings appear — seeds germinate in 7–14 days. Thin seedlings to the final spacing once they are big enough to handle. If you start indoors, use individual pots and transplant very young, before the roots fill the pot, since sweet peas dislike root disturbance.
Give sweet peas a trellis, fence or obelisk from the start: they climb by tendrils and need support to reach their full height, and a plant without support sprawls and rots on damp soil. Tie young shoots loosely to the support until the tendrils take hold. Pinch out the growing tip once plants have a few sets of leaves to encourage bushy growth and more flowers. Water seedlings in well at planting time and mulch around the base to keep roots cool.
Soil, spacing, sun and water
Sweet peas want full sun and rich, moist, well-drained soil with a pH of 6.0–7.5. Dig in well-rotted compost before planting — sweet peas are hungry feeders, unlike cosmos and nasturtiums — and space plants 6–8 inches apart along the trellis, since crowded plants stay damp and invite disease. Mulch thickly to keep the soil cool and evenly moist, which matters more for sweet peas than for most flowers, since hot roots stop them flowering. In Zone 13's heat, a thick mulch and steady water are the difference between flowers and failure.
Sweet peas need moderate water: water deeply and less often rather than lightly every day, water at the base in the morning so leaves dry before night, and check the soil a finger's depth down, watering when it feels dry there. In Zone 13's heat, even a cool-season plant in full sun dries out fast, so do not let the soil dry out while plants are in flower. The watering calculator can help you work out a routine that keeps sweet peas moist without waterlogging them.
Companion planting
Good companions for sweet peas include lavender, marigolds, garlic and chives. Lavender and marigolds draw pollinators and beneficial insects to the bed, while garlic and chives are traditional companions said to deter aphids. The companion planting finder can suggest combinations for your whole bed. Sweet peas also sit happily beside other cool-season flowers such as pansies and snapdragons at the foot of the trellis, filling the soil while the vines climb above them.
Give sweet peas the sunniest cool-season spot and a sturdy support, and keep their roots cool with mulch and low ground cover. Avoid planting them where the soil stays soggy, and keep them away from plants that need very dry soil, since sweet peas like steady moisture. As members of the pea family, sweet peas fix nitrogen in the soil, which benefits the plants that follow them in the bed.
Pests and problems
The common pests and problems to watch for with sweet peas are aphids, bean beetles, slugs and cutworms. Aphids cluster on shoot tips and buds and can distort new growth, so check the undersides of leaves weekly and wash small colonies off with a strong jet of water. Slugs chew ragged holes in leaves and young shoots, especially in damp weather, so look under pots and mulch in the morning. Cutworms can sever young stems at soil level, so protect fresh seedlings with a simple collar pushed into the soil around each stem. Bean beetles chew leaves and pods — hand-pick them in the morning when they are sluggish.
In Zone 13's year-round warmth, pests never get a winter break, so check plants weekly rather than waiting for damage to show. Good air flow helps: space plants properly, avoid overhead watering late in the day, and remove spent flowers and damaged leaves promptly. Powdery mildew can appear in humid weather — water at the base, mulch, and give plants room to breathe rather than crowding them.
Harvest and storage
Sweet peas flower 60–70 days after sowing, and picking keeps them coming — the more you cut, the more they flower. Cut stems in the cool of the morning, choosing flowers that have just opened, and cut long stems down to a leaf joint. Deadhead spent flowers every few days so the plant does not waste energy on seed, and never let pods form if you want flowers to continue. In the heat of the hottest months, flowering slows and then stops, so enjoy the display while it lasts and compost plants once they are spent.
For the vase, cut stems in the morning, strip the lower leaves, and put stems straight into cool water — and enjoy the scent, which is the whole point of growing them. Never eat sweet pea flowers or seeds: unlike edible peas, sweet peas are poisonous. Save seed only if you enjoy experimenting — seedlings rarely match the parent plant, so most gardeners buy fresh seed each cool season.
Making the most of Zone 13
Zone 13's advantage is time, but sweet peas are a cool-season exception: they give you a short, scented season in the coolest months and then make way for heat-lovers. The trick is to sow for the cool season, pick constantly, and keep a simple notebook of what you sowed and when it flowered — after one season you will have a record far more useful than any general guide. Related reading: snapdragons share the same cool-season habits, and January in Zone 13 is a great month to plant. Pansies in Zone 13 make a lovely low companion at the foot of the sweet pea trellis. Related reading: Snapdragons in Zone 13 share the same habits, and January in Zone 13 is a great month to plant. For a planting plan tailored to your postcode, try the planting calendar by zip.
Frequently asked questions
When should I plant sweet peas in Zone 13?
Plant sweet peas in the coolest months, roughly November to February, when nights are at their mildest. Zone 13 is frost-free with winter lows above 60°F, so there is no last frost date to count back from. Check your local extension service — these are zone averages, not exact dates for your garden.
How long do sweet peas take to grow in Zone 13?
Seeds germinate in 7–14 days, and plants flower 60–70 days after sowing. In Zone 13, sow in time for the coolest months so flowers arrive before the hot season, since heat shortens the display.
Can I grow sweet peas all year in Zone 13?
No — sweet peas are a cool-season flower and fade fast in Zone 13 heat. Grow them as a cool-season annual from November to February, then replace them with heat-lovers such as cosmos or nasturtiums for the hot months.
What soil and spacing do sweet peas need in Zone 13?
Sweet peas need full sun and soil pH 6.0–7.5, spaced 6–8 inches apart along a trellis. Dig in well-rotted compost, mulch thickly to keep roots cool, water at the base, and test your soil through your local extension service.
Are sweet peas edible like garden peas?
No — sweet pea flowers and seeds are poisonous, unlike edible garden peas. Grow them for their scent and flowers only, and keep the seed pods away from children and pets.