Often overlooked by home gardeners, kohlrabi is an intriguing and delicious addition to your herbaceous ‘hood. Technically a part of the cabbage family, kohlrabi is mostly grown for its swollen stem, harvested when full and globe-shaped. Plants can be white, green, or even purple. Although a biennial plant, it’s commonly grown as an annual, reaching a height of several feet with large leaves arising one by one from the stem. Leaves are harvested for consumption when young and tender. The flavor of the bulb is described as similar to turnip and cabbage but is both milder and sweeter.
The Early Purple Vienna kohlrabi shares many characteristics with its paler relatives, but its deep purple outer skin makes it stand out from the rest. An heirloom type from pre-1860, it’s good when eaten raw or cooked. High yields and crisp texture, plus its beautiful color, make this variety an excellent choice for the home gardener. Plants will get up to 18″ tall and bulbs should be harvested when under 3″ in diameter for best results. Early Purple Vienna also offers some resistance to cabbage worms.
Seed Depth: 1/4–1/2″
Space Between Plants: 6–12″
Space Between Rows: 18–24″
Germination Soil Temperature: 60–70°F
Days for Germination: 7–2-
Sow Indoors: 4–6 weeks before average last frost date.
Sow Outdoors: 3–4 weeks before average last frost date. For a fall crop, start 10–12 weeks before average first frost date.
Vegetative: Possible to start plants from cuttings, but this is not recommended.
Grows best in cool weather. Will taste best when it can mature while daytime temperatures are between 60–65°F. Planting schedules should be adjusted based on your zone. In temperate climates, start seeds or set out transplants in the spring for a summer harvest or late summer for a fall harvest. In warmer climates, plant in late summer or early fall for a winter or early spring harvest.
Natural: Full sun. Partial shade if growing in warmer seasons.
Artificial: Grows well under fluorescent or LED bulbs.
Soil: Prefers well-drained loamy soil but will grow well in almost all soil types. A pH of between 6.5–6.8 will keep plants healthy and nourished.
Soilless: Germinate seeds or root cuttings in a soilless mix.
Hydroponics: Will thrive in an ebb and flow hydroponic system using clay pellets or perlite.
Aeroponics: Will thrive in an aeroponic system, especially when in the younger growth stages.
Water: Requires moderate levels of water. Aim for approximately 1.5 inches per week in dry weather, reducing watering if precipitation increases.
Nutrients: Requires low to moderate levels of nutrients. Use wood ash to provide potassium. A source of calcium may be beneficial as well. Apply an organic fertilizer such as compost, manure, or cottonseed meal once the bulbs have started to form, but be careful not to add too much nitrogen or bulbs may split.
Foliar: Apply fish emulsion every other week if young plants are stunted or are producing small leaves.
Mulching: A layer of organic mulch may be added around the base of the plant to add nutrients to the soil, maintain soil moisture, and suppress weeds.
Rotation: Practice a 2- to 3-year rotation away from all other members of the brassica family.
Companions: Grows well with beets, herbs, potatoes, and members of the onion family. Avoid tomatoes, strawberries, and beans.
Harvest: Plant stems should be harvested by cutting from the base of the plant when they reach about 2–3″ in diameter. Leaves can be harvested at any age, but don’t take too many or you’ll risk stunting the stem’s growth.
Storage: Both the stem and leaves will keep in the refrigerator. Stems can last as long as four weeks; however, they become tougher the longer they are stored.
Fun Fact: Purple Vienna kohlrabi only have purple outsides. The inner flesh is still a creamy white to light green color.
Preserve: Easy to preserve, kohlrabi stems can be fermented as a sauerkraut, pickled, or blanched and peeled before being frozen. Leaves may be dehydrated à la kale chips and eaten as a tasty snack or stored in an airtight container for later use in soups or stews.
Prepare: Stems should be peeled with a paring knife prior to eating or cooking as they can be tough and do not soften easily. Kohlrabi stems may be eaten raw, as part of a coleslaw or salad, or roasted. Leaves can be cooked similar to other leafy greens by sautéing, chopping for a salad, or adding to stir fries.
Nutritional: Rich in vitamin C and fiber, kohlrabi is as nutritious as other members of the cabbage family. In addition to fiber and many vitamins, it’s also a good source of copper and manganese.
Medicinal: As is the case with other cruciferous vegetables, kohlrabi has been noted as a veggie with potential cancer-preventing properties due to its content of glucosinolates, which help detoxify the liver, and antioxidants, which can prevent cell mutation.
Try out this Super Creamy Potato and Kohlrabi Soup on a cool fall day.