Overview
The biennial radish, a salad favorite, is most commonly grown as an annual and will survive some summer heat but prefers the cooler weather of spring or fall. Keep a loving eye on this crop, because radishes will turn pithy and hot if left in the ground for too long. Leaves resemble arugula in shape, are a deep green color, and develop spines as they mature. Don’t let that scare you from chowing down on these tasty greens: leaves can be eaten raw when young or cooked when older.
The French Breakfast Radish has been popular with gardeners for at least 100 years, so keep tradition alive by planting this delicate tasting root veggie in your garden. Expect each plant to produce one 3–4″ long red-skinned radish, ready for harvest about a month after planting. This type grows best in the spring.
- Botanical Name: Raphanus sativus
- Plant Type: Cover Crop Vegetable
- Variety: French Breakfast
- Growth Cycle: Annual Biennial
- Season(s): Spring Summer Fall Winter
- Climate Zone(s): 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a 10b
- Light: Full Sun Partial Shade
- Soil Type(s): Clay Loamy Sandy
- Yield: 0.1 oz per plant
- Garden Dimensions: 6 plants per square foot
- Germination: 3–10 days
- Maturity: 20–30 days
- Harvest: 28–35 days
Cultivation
Propagation
Seed:
Seed Depth: 1/2–1″
Space Between Plants: 1″, thin to 2″
Space Between Rows: 8–12″
Germination Soil Temperature: 40–85°F
Days for Germination: 3–10
Sow Indoors: Not recommended.
Sow Outdoors: 4 to 6 weeks before average last frost.
Climate
Radishes prefer cooler weather and will do best when planted in the spring or fall in most climate zones. They can tolerate moderate heat if kept watered and partially shaded during hot spells. Note that if growing in warm weather, your cropmay flower earlier than desired.
Light
Natural: Full sun. Although partial shade may be beneficial in extremely hot weather, in more moderate climates shade will cause radishes to put more energy into growing bigger leaves which can lead to stunted root vegetables.
Artificial: Can grow well indoors in a bright window. However, if using strictly artificial lighting, fluorescent bulbs will be your best option. Plants require between 8 to 10 hours of light a day.
Growing Media
Soil: Will grow in most types of soil but prefers well-drained, loose soil. A pH of 5.5 to 6.8 will keep plants healthy and nourished.
Soilless: Not recommended for germination, since radishes do not transplant well. If growing indoors use a nutrient-balanced soilless mix in sufficiently deep containers.
Hydroponics: Will thrive in ahydroponicsystem. Horizontal systems are considered best for most radish varieties.
Aeroponics: Possible but not recommended.
Care
Water: Requires moderate levels of water. Soil should be kept moist but not saturated. Avoid letting thesoil dry out as the plants will develop a woody taste and tough texture.
Nutrients: Requires moderate levels of nutrients. Fertilizing is most important for radishes prior to planting, so apply compost or a balanced fertilizer to the soil before transferring or starting your seeds. Be careful not to over-fertilize (particularly with nitrogen) as this can cause the leaves on radishes to grow quickly and sap nutrients from the root.
Foliar: A balanced, liquid fertilizer can be used on seedlings after they have been thinned. Again, too much fertilizer can cause the plant to focus its energy on leaf growth.
Pruning: Thin when seedlings have reached a couple inches tall and apart.
Troubleshooting
Pest(s):
- Aphids
- Cabbage root maggots
- Flea beetles
- Leaf hoppers
- Slugs
- Snails
Disease(s):
- Club root
- Damping-off
- Downy mildew
- Scab
Rotation and Companion Plants
Rotation: A 3-year rotation away from all crops in the Brassica family is recommended to avoid proliferation of soil diseases.
Companions: Grows well with chervil, peas, cucumber and peppers. Avoid hyssop.
Harvest and Storage
Harvest: Will be ready to harvest in approximately a month after planting, but it doesn’t hurt to start checking them around the 3-week mark. To test the size of the radish, rub around the root at soil level to estimate the girth of the plant. Radishes will be ready when they have reached approximately 1 to 2″ in width.
Storage: Cutting off the greens will allow radish roots to keep longer either in the refrigerator or in a bag with holes to allow air flow. The greens can also be eaten and may be kept in the refrigerator for up to a week.
Other Info
Other Uses: Due to the ease with which they grow as well as their affinity for cooler weather, radishes have been found to be an excellent cover crop. They assist in loosening and draining soil and add organic material to the dirt whenleft to decompose.
