Sweet pea (Lathyrus odoratus) — Plotwright

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Sweet pea

Habit (mature) · Magnus Manske / Wikimedia Commons · CC BY-SA 3.0

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Sweet pea

Lathyrus odoratus

A cool-weather annual climber grown for intensely fragrant flowers — the species epithet odoratus means "fragrant" — carried on winged stems whose tendrils let plants twine to 6-8 feet in a single season. Cultivars bloom in every color except yellow, May through July. A challenge in hot, humid summers: as temperatures rise the plants decline rapidly, so it is sown early for a cool-season show. The pea-like fruits, unlike edible garden peas, are inedible and poisonous to humans.

Review: Source-backed

Climate fit: moderate (63/100)

Filler

Container

Pollinator

Light

Full sun / Part shade

Water

Consistent moisture

Mature size

36-96" tall · 6" apart

Lifecycle

True annual (one season)

Summer heat range

Cool-Warm

cool to warm summers Interim Plotwright tier until the plant AHS range is authored.

Native in Illinois

No

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Cold hardiness

Now

Zone 6b

USDA

Chicago, IL · 1991-2020 average annual coldest day

Source: USDA Plant Hardiness Zone Map 2023 (1991-2020 climatology) via ArcGIS FeatureServer

Well-suited

2050

Zone 7b

Plotwright

Your zone + climate-model shift · SSP3-7.0 (regional rivalry)

Well-suited

In plain terms: cold winters — coldest nights typically around -3°F.

✓

Well-suited today and still thriving in 2050.

Heat tolerance

°C

°F

Loading current AHS heat-zone and plant heat-fit data at your coordinates…

Where this plant fits

Suitable across 45 ecoregions — 45 climate-resilient through 2070. Best matches first.

Appalachian mixed mesophytic forests

Appalachian-Blue Ridge forests

Arizona Mountains forests

Atlantic coastal pine barrens

Blue Mountains forests

California coastal sage and chaparral

Canadian Aspen forests and parklands

Central Pacific Northwest coastal forests

Central Tallgrass prairie

Central-Southern Cascades Forests

Sources & citations

Cite this page

For lesson plans, articles, or research that uses this page. To cite a single upstream fact instead, use its specific source listed below.

Plotwright. (2026, May 17). Sweet pea (Lathyrus odoratus). Retrieved 2026, June 5, from https://plotwright.garden/plants/sweet-pea

Sources for every fact

Every fact on this page traces to a source. 18 fields cited — 18 source-backed.

Missouri Botanical Garden PlantFinder

Botanical research database

Backs 17 fields

Identity

Summary

Plant type

Light

Moisture

Hardiness

Heat zone

Size

Spacing

Habit

Design roles

Seasonal interest

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Lifecycle

Regional guidance

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Wikimedia Commons

Photo · CC BY-SA 3.0

Backs 1 field

Image

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The photos above are our reviewed reference set, curated for accuracy.

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