Kohlrabi (Brassica oleracea (Gongylodes Group))
Grow tender, sweet Kohlrabi, a cool-season Brassica oleracea (Gongylodes Group) vegetable. Easy to maintain with low water needs in full sun.
Complete Plant Information
Overview
Kohlrabi, scientifically known as Brassica oleracea (Gongylodes Group), is a distinctive and fast-maturing cool-weather vegetable prized for its swollen stem base, which resembles a small turnip. This feature, which gives Kohlrabi its common name deriving from German words for cabbage and turnip, offers a unique texture and flavor profile perfect for fresh eating. Gardeners appreciate this member of the Brassicaceae family for its relatively low maintenance requirements and quick return on investment during the cooler parts of the growing season.
Unlike its cousins broccoli and cauliflower, the primary harvest of Brassica oleracea (Gongylodes Group) is the enlarged, edible stem swelling that emerges just above the soil line. It thrives when planted during the cool temperatures of spring or fall, indicating its intolerance for sustained high summer heat. Successfully growing Kohlrabi means providing consistent moisture and rich, well-drained soil to ensure the bulbs develop tenderly before they turn woody.
Though an annual vegetable crop, the Kohlrabi plant offers versatility; the bulbs can be enjoyed raw in slaws or cooked, and the leafy tops are also edible. Integrating this striking vegetable into your garden provides both culinary novelty and functional foliage growth, establishing it as a reliable producer for gardeners operating within USDA Hardiness Zones 2 through 11.
Fast Facts
- Plant Family: Brassicaceae
- Plant Type: Annual
- Hardiness Zones: USDA Zones 2-11
- Size at Maturity:
- Height: 0.75-1 ft
- Spread: 0.75-1 ft
- Bloom Time: Rarely flowers
- Sun Exposure: Full sun
- Water Needs: Medium
- Maintenance Level: Low
How to Grow
Kohlrabi cultivation succeeds best in organically rich, consistently moist, well-drained loams. The ideal soil pH range for Brassica oleracea (Gongylodes Group) is between 6 and 7. Since this is a cool-season vegetable, timing is crucial; plants grow poorly if daytime temperatures consistently exceed 80°F. For a spring crop, sow seed indoors 6-8 weeks before the last expected frost, or direct sow outdoors about two weeks prior to this date.
When transplanting seedlings outside, space them approximately 4-6 inches apart in rows set 18 inches apart. Fall harvests are achieved by starting seeds indoors around July 1st and transplanting the resulting seedlings into the garden by mid-August, ensuring they mature during cooling autumn weather. Consistent moisture management is vital for developing quality bulbs.
Apply mulch around the plants to help protect their shallow root systems, suppress weeds, and conserve essential soil moisture. Harvest Kohlrabi when the swollen stems reach a tender 2-3 inches across; allowing them to grow larger than 3 inches typically results in tough, woody texture. Crop rotation is an important cultural practice to employ annually to minimize the buildup of soil-borne diseases affecting the Brassica oleracea (Gongylodes Group).
Landscape Uses
As a dedicated vegetable, Kohlrabi finds its ideal placement within the dedicated kitchen garden space. Its compact growth habit, reaching only about 1 foot tall and wide, makes Brassica oleracea (Gongylodes Group) suitable for intensive planting schemes or block gardening where maximizing yield in a small area is the goal. The slightly architectural habit of the plant, with its upward-reaching leaves, provides a nice textural contrast when planted alongside lower-growing herbs or trailing edibles.
While primarily culinary, well-maintained beds of Kohlrabi can provide an orderly, functional aesthetic in cottage garden settings. Consider interplanting these cool-season crops with annual flowers that enjoy similar conditions, although direct companion planting advice should be sought based on specific neighboring vegetables. For gardeners focusing strictly on yield, integrating Kohlrabi ensures a harvest window often missed by summer vegetables.
Standout Features
Noteworthy Characteristics
Brassica oleracea (Gongylodes Group), commonly called kohlrabi, is a cool weather vegetable that produces fat, rounded, turnip-like enlargements of the stem just above the soil surface. Kohlrabi is best picked when it reaches 2-3” across (tender and sweet when small), as it usually becomes tough and woody if allowed to grow beyond 3” across. The leafy tops, which taste reminiscent of turnip greens, may also be harvested, adding further value to this versatile plant.
Tolerances
- None listed
Potential Problems
Kohlrabi is susceptible to several common garden pests, requiring vigilance throughout its short growing season. Potential insect issues include infestations by aphids, cabbage loopers, cabbageworms, cutworms, and flea beetles, which can severely damage the leaves and developing bulbs of the Brassica oleracea (Gongylodes Group). Regular inspection and the use of floating row covers can help manage early infestations of flying insects.
Disease pressure can also affect crop success. Potential disease problems include downy mildew and bacterial or soft rot, often exacerbated by overly wet conditions or overcrowding. Ensuring proper air circulation by adhering to recommended plant spacing and maintaining consistent, but not excessive, moisture levels will greatly aid in prevention. Crop rotation is essential to break disease cycles in the soil.
Frequently Asked Questions
What hardiness zones is Kohlrabi suitable for?
Kohlrabi is suitable for a very wide range of climates, thriving in USDA Zones 2 through 11.
How large does Kohlrabi grow?
This annual vegetable typically grows to a height between 0.75 and 1 foot tall, with a similar spread of 0.75 to 1 foot at maturity.
What sun exposure does Kohlrabi need?
Kohlrabi requires full sun to establish and produce its best crop.
When does Kohlrabi bloom?
Kohlrabi rarely flowers unless stressed by high heat, in which case it will bolt.
Conclusion
Kohlrabi offers gardeners a unique, quick-growing, and highly versatile cool-season harvest, celebrated for its tender bulbs and edible greens. Integrating Brassica oleracea (Gongylodes Group) into your spring or fall rotation adds diversity to your vegetable patch. Before planting, confirm your local frost dates and ensure soil preparation focuses on richness and excellent drainage for this low-maintenance crop.
Seasonal Care Calendar
For spring crops, focus efforts on early soil preparation, aiming for planting outdoors about two weeks before the last expected frost date. During the active growth phase of spring Kohlrabi, consistently monitor moisture; applying mulch will significantly aid in keeping the soil cool and moist, which is critical for preventing the bulbs from becoming woody before time.
The fall planting cycle requires backward planning, starting seeds indoors around July 1st for mid-August garden installation. This timing ensures the Brassica oleracea (Gongylodes Group) matures during the decreasing temperatures of early autumn, yielding the sweetest bulbs. Post-harvest cleanup is simple, but be diligent about crop rotation to maintain soil health for next year’s brassicas.
Companion Planting Strategies
Kohlrabi benefits greatly from companion planting techniques that help deter common associated pests. Planting strongly aromatic herbs nearby, such as dill, rosemary, or mint, can help confuse or repel flying pests like cabbage moths and flea beetles. These aromatic companions utilize the same desirable sun and medium water conditions as the Kohlrabi.
Avoid planting other heavy feeders from the Brassica family too closely, as they share susceptibility to similar diseases and nutrient demands. Instead, consider planting root vegetables like carrots or deep-rooted lettuces as neighbors in your vegetable garden, as they occupy slightly different soil niches and utilize surface nutrients differently.
