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
All Zone 7 root-vegetable →Zone Map
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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 | — | — | May – June | August – October |
| Zone 4 | — | — | April – June | July – October |
| Zone 5 | — | — | April – May | July – November |
| Zone 6 | — | — | April – May | July – November |
| Zone 7 | — | — | March – May | June – November |
| Zone 8 | — | — | March – April | June – December |
| Zone 9 | — | — | February – March | May – December |
| Zone 10 | — | — | 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
Fresh watermelon radishes store exceptionally well compared to smaller radish varieties. Remove greens immediately, leaving 1 inch of stem, and brush off excess soil without washing. Store in perforated plastic bags in your refrigerator's crisper drawer at 32-35°F with high humidity.
Properly stored roots maintain quality for 3-4 weeks, though their stunning color may fade slightly. Don't wash until ready to use, as moisture accelerates decay.
For preservation, watermelon radishes excel at quick pickling—slice thin and pickle in rice vinegar with sugar and salt for spectacular pink pickles. They also ferment beautifully in salt brine, developing complex flavors while retaining crunch. Roasting concentrates their sweetness, but freezing isn't recommended as it destroys their crisp texture. Dehydrated slices make colorful, peppery chips when dried at 125°F for 8-12 hours.
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
Carrots
Different root depths prevent competition, carrots help break up soil for radish growth
Lettuce
Shallow roots don't compete, provides ground cover and efficient space utilization
Spinach
Fast-growing leafy green that can be harvested before radishes need full space
Peas
Fix nitrogen in soil benefiting radish growth, different growth habits complement each other
Chives
Repel root maggots and other pests that attack radishes
Nasturtiums
Act as trap crop for flea beetles and aphids that commonly attack radishes
Marigolds
Repel nematodes and other soil pests, deter flea beetles
Cucumber
Radishes can deter cucumber beetles while cucumbers provide shade for cool-season radishes
Keep Apart
Brassicas
Same family plants compete for nutrients and attract similar pests like flea beetles and clubroot
Hyssop
Inhibits growth of radishes and other root vegetables through allelopathic compounds
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #169276)
Pests & Disease Resistance
Resistance
Good cold tolerance and slow to bolt
Common Pests
Flea beetles, cabbage root maggots, aphids
Diseases
Clubroot, black rot, white rust