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Sweet Pea
Lathyrus odoratus
Sweet Pea blooms from May through July.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Sweet Pea
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 2–11. Expect it to reach about 6 ft tall and 1.5 ft wide at maturity, in roughly 1 year (not yet checked).
What was checked
Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Sweet Pea
Wait until all danger of frost has passed, then plant out Sweet Pea into warm soil; in most zones that means late spring. Planted then, it flowers from May to July.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Sweet Pea get?
6 fttall5 ft 7 inan adult1.5 ftwideSee Sweet Pea in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Sweet Pea
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Sweet Pea about 1.5 ft apart, center to center, so each plant has room to reach its full width.
Add Sweet Pea to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Sweet Pea's height, spread, hardiness zones, sun and trait tags were checked against 8 published sources on July 30, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical GardenLathyrus odoratusheight, spread, hardiness zones, sun, years to mature size and trait tags
- NC State ExtensionLathyrus odoratusheight, spread, hardiness zones, sun, years to mature size and trait tags
- NC State ExtensionLathyrus, the genus entryheight, spread, hardiness zones, sun and trait tags
- RHSRoyal Horticultural Society (Lathyrus odoratus)height, spread, sun, years to mature size and trait tags
- u.osu.eduOhio State University Extension, Knox County Agricultural News (Succes...height, sun, years to mature size and trait tags
- Iowa State University ExtensionAnnual Flowering Vinesheight, years to mature size and trait tags
- ucanr.eduUC Marin Master Gardeners, UC ANR (Sweet peas grown with ease)height, sun and trait tags
- University of Illinois ExtensionIllinois Extension Flowers (Sweet Pea)height and trait tags
How the checking works, and what each standard covers, is on the verified plants page.
Comes in 5 varieties across 4 colors
Same plant, same care - pick the color you are growing.
Compare every variety in the Sweet Pea group
Every figure is the variety's own page fact. Tap a name to open it.
| Variety | Color | Blooms | Hardiness | Sun | Size (H × W) |
|---|---|---|---|---|---|
| Cupani | Purple | May–Jul | Zones 2–11 | Full sun | 6 ft × 1.5 ft |
| Lavender | Purple | May–Jul | Zones 2–11 | Full sun | 6 ft × 1.5 ft |
| Royal Blue | Blue | May–Jul | Zones 2–11 | Full sun | 6 ft × 1.5 ft |
| Royal Crimson | Red | May–Jul | Zones 2–11 | Full sun | 6 ft × 1.5 ft |
| Royal White | White | May–Jul | Zones 2–11 | Full sun | 6 ft × 1.5 ft |
| Sweetthis page | Pink | May–Jul | Zones 2–11 | Full sun | 6 ft × 1.5 ft |
Good to know about Sweet Pea
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note. A note reports what its source says; where that differs from a fact above, the fact above is this entry's stored value, and its mark says whether it has been checked.
Safety
The seeds and pods are poisonous: do not eat them, and do not confuse this with the edible garden pea it resembles. Keep seeds from children and pets. per NC State and Missouri Botanical Garden
Worth knowing
The more you cut it for the vase, the more it blooms: once seed pods form, flowering slows and stops, so picking the fragrant stems keeps it going. per NC State
ASPCA rating can mislead
ASPCA lists sweet pea non-toxic to dogs and cats but toxic to horses. That means a nibble rarely harms a pet, not that the seeds are safe to eat. per ASPCA and NC State
A cool-season spring crop
A cool-season annual: it likes cool weather, shrugs off a little frost, then declines fast once summer heat and humidity arrive. Replace it when it quits. per NC State
Climbs; give it support
The winged stems climb by tendrils, so set up a trellis, netting, or twiggy branches at planting. Left unsupported it flops into a low bushy mound. per NC State
Sow early in cool weather
Sow early while it is cool: in mild-winter areas in fall, elsewhere as soon as the soil can be worked, or indoors 6 to 8 weeks before last frost. per NC State
Fragrant blooms in many colors
Its name odoratus means fragrant. It carries pea-shaped blooms in nearly every color except yellow, which is the whole reason to grow it. per Missouri Botanical Garden
What pairs well with Sweet Pea
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Candytuft
Shares full sun and low to moderate water; opens in mid spring and overlaps into this one's season; low at 10 in, to carpet the ground beneath; evergreen, so the bed keeps its shape through winter.
Goldenrod
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds; lower at 3 ft, for the front of the border.
Autumn Joy Sedum
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds; lower at 1.5 ft, for the front of the border.
Siberian Squill
Shares full sun and moderate water; blooms in early spring, before this one opens; low at 6 in, to carpet the ground beneath.
Hyacinth
Shares full sun and moderate water; blooms in early spring, before this one opens; low at 10 in, to carpet the ground beneath.
Pampas Grass
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds; its white flowers settle the pink.
Little Bluestem
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds.
Fountain Grass
Shares full sun and low to moderate water; blooms in late summer as this one finishes; its seed heads stand through winter, for structure and the birds.
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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.