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Sweet pea

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 to 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.
Climate fit: moderate (68/100)
Filler
Container
Pollinator
Light
Full sun / Part shade
Water
Consistent moisture
Mature size
3-8 ft tall · 6" apart
Lifecycle
True annual (one season)
AHS heat range
1-9
Plant range authored in AHS heat-zone terms.
Native in Illinois
No

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Bees can visit and trip the keel, but a pollinator is not required for seed set.

Cold hardiness

These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.
Now
Zone 6b
Plotwright
USDA Zone 6b
-5°F to 0°F
Well-suited
Zone 7a
Plotwright
0°F to 5°F
Well-suited
In plain terms: This location has cold winters. Its winters are projected to keep warming through 2050.
Well-suited today and still thriving in 2050.

Heat tolerance

Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.
Loading AHS heat-zone data for this location...

Similar plants

Browse lateral options with similar roles, light needs, size, or native-range overlap; these are not filtered for a better climate fit.
Common zinnia (Zinnia elegans) shown head-on as a fully double orange flower, the central disc florets curled into a tight yellow spiral.
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Close-up focus-stacked photograph of a single Chionodoxa forbesii flower showing sky-blue star-shaped petals and a white center with yellow anthers
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Moderate water
Zones 3a-8b
Climate: moderate
Border
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Heather (Calluna vulgaris) in full late-summer bloom, a dense low mat of wiry stems covered in spikes of tiny mauve-purple flowers.
Calluna vulgaris
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Heather, or ling (Calluna vulgaris), is the low, wiry evergreen shrub that colours the moors and heaths of Europe purple in late summer. It grows only 4 inches to 24 inches tall in dense, spreading mats of tiny scale-like leaves, and from July to September it is covered in spikes of mauve (wild) to white, pink, or red (cultivar) flowers that draw an intense traffic of bees - the source of prized heather honey. It is beautiful, wildlife-rich, and extremely cold-hardy, but it is also a fussy plant with two non-negotiable demands: genuinely acidic soil and cool summers. The honest catches: it will not thrive on chalk or in hot, humid heat (NC State advises against planting south of zone 6), and where introduced - notably New Zealand - it has become an invasive weed.
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Climate: narrow
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Sweet alyssum (Lobularia maritima) showing dense clusters of tiny white four-petaled flowers with yellow-green centers and small green buds against narrow gray-green leaves.
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Sweet alyssum
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Container
Bluebeard (Caryopteris × clandonensis 'Dark Knight') - dense clusters of deep violet-blue tubular flowers on upright stems with gray-green aromatic foliage.
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Bluebeard
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Helichrysum italicum
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A dwarf, evergreen Mediterranean sub-shrub with intensely aromatic silver-grey needle-like leaves and clusters of small, long-lasting yellow button flowers in summer. Native to the dry, rocky ground of the western and central Mediterranean basin, it is prized for its bold textural foliage and the illusion of a curry scent - although the plant has no culinary relationship to curry spice and its flavor largely disappears on cooking. The honest catch is hardiness: Helichrysum italicum is reliably winter-hardy only to about USDA Zone 8 (around 10°F); in colder climates it either dies outright or must be overwintered frost-free, and even within its range it is short-lived on heavy, wet soils where winter root rot claims it quickly.
Shrub
Full sun
Low water
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Climate: narrow
Border
Filler
Pollinator
Container

Educator packet

Plant packet
Sweet pea educator packet
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 to 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.
Scientific name
Lathyrus odoratus
Plant type
annual
Hardiness
2-11
Light
full-sun, part-shade
Moisture
consistent
Spacing
6 inches
Classroom prompts
- Which plant traits are observations, and which are care recommendations?
- How would this plant fit change if the garden location moved warmer, colder, wetter, or drier?
- Which source-backed facts would you cite in a lesson handout?
Use the Sources & citations section below for page citation styles and the field-level source list.

Sources & citations

Cite this page
For lesson plans, articles, or research that uses this page. Use the source cards below to explore the references that informed this record.
Plotwright. (2026, May 17). Sweet pea (Lathyrus odoratus). Retrieved 2026, August 20, from https://plotwright.com/plants/lathyrus-odoratus
Sources used for this record
This record is compiled from the sources below.
Plants of the World Online (POWO)
Botanical research database
Missouri Botanical Garden PlantFinder
Botanical research database
RHS Find a Plant
Botanical research database
GBIF
Botanical research database
Wikimedia Commons
Photo · CC BY-SA 3.0