Watermelon Radish
Lathyrus odoratus
Large 2" blossoms in bright, clear colors of red, purple, mauve, pink, blue, and white. Blooms over a long period with exceptional fragrance. Can be spelled either as sweet pea or sweetpea. Attracts hummingbirds.
Harvest
90d
Days to harvest
Sun
Full sun
Zones
2–11
USDA hardiness
Height
3-8 feet
Planting Timeline
Showing dates for Watermelon Radish in USDA Zone 7
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Watermelon Radish · Zones 2–11
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | March – April | May – June | May – June | August – October |
| Zone 4 | March – April | May – June | April – June | July – October |
| Zone 5 | February – March | April – May | April – May | July – November |
| Zone 6 | February – March | April – May | April – May | July – November |
| Zone 7 | February – March | April – May | March – May | June – November |
| Zone 8 | January – February | March – April | March – April | June – December |
| Zone 9 | January – January | February – March | February – March | May – December |
| Zone 10 | January – January | February – March | January – March | April – December |
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day). Soil: High Organic Matter. Drainage: Good Drainage, Moist. Height: 3 ft. 0 in. - 8 ft. 0 in.. Spread: 2 ft. 0 in. - 3 ft. 0 in.. Spacing: 3 feet-6 feet. Growth rate: Rapid. Maintenance: Medium. Propagation: Seed. Regions: Coastal, Mountains, Piedmont.
Harvesting
Type: Legume.
Bloom time: Spring, Summer
Edibility: Sweet pea fruits are inedible and poisonous to humans.
Storage & Preservation
Store fresh watermelon radishes in the refrigerator with tops removed, wrapped in perforated plastic bags in the crisper drawer. They'll maintain quality for 2-3 months at 32-35°F with high humidity. Never store at room temperature—they'll become pithy within days.
For preservation, watermelon radishes excel at quick pickling due to their mild flavor and stunning color. Slice them thin and pickle in rice vinegar for an authentic Asian preparation. They also ferment beautifully into kimchi-style preparations, maintaining their crunch and developing complex flavors.
Roasted watermelon radishes make an excellent winter side dish—cut into wedges, toss with olive oil and herbs, then roast at 425°F until tender. They can be frozen after blanching for 2 minutes, though the texture becomes softer and they're best used cooked rather than fresh after freezing.
History & Origin
Origin: Southern Italy, Sicily, Crete
Advantages
- +Attracts: Butterflies
- +Edible: Sweet pea fruits are inedible and poisonous to humans.
- +Fast-growing
Considerations
- -Toxic (Seeds): Low severity
Companion Plants
Plant Together
Lettuce
Shallow roots don't compete, provides ground cover and efficient space use
Spinach
Cool season companion with non-competing root system, good succession planting
Carrots
Deep taproots don't compete with shallow radish roots, different growth habits
Nasturtiums
Trap crop for flea beetles and aphids that commonly attack brassicas
Dill
Attracts beneficial insects like parasitic wasps that control cabbage worms
Onions
Strong scent deters flea beetles and root maggots that target radishes
Marigolds
Natural pest deterrent, repels nematodes and various brassica pests
Chives
Repels aphids and other soft-bodied insects, improves soil health
Keep Apart
Tomatoes
Heavy feeders that compete for nutrients, may stunt radish growth
Pole Beans
Create too much shade and compete for nutrients, radishes prefer full sun
Fennel
Allelopathic properties inhibit growth of most brassicas including radishes
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #169276)
Pests & Disease Resistance
Resistance
Good resistance to clubroot and splitting
Common Pests
Flea beetles, cabbage root maggots
Diseases
Clubroot, black rot, downy mildew