Kohlrabi

Soil Preparation

Kohlrabi thrives in well-drained, fertile soil rich in organic matter. Before planting, aim for a soil pH between 6.0 and 7.0. It's a good idea to amend your garden bed with a generous layer of compost or well-rotted manure, especially if your soil is heavy clay or very sandy. This enriches the soil, improves drainage, and provides a slow-release source of nutrients. Work the soil to a depth of at least 8-10 inches, breaking up any large clumps to create a fine, crumbly texture that young roots can easily penetrate.

Planting

Kohlrabi is a cool-season crop, meaning it prefers cooler temperatures and can even tolerate light frosts. For an early spring crop, you can start seeds indoors 4-6 weeks before the last expected frost, or direct sow them outdoors once the danger of hard frost has passed. For a fall crop, direct sow in mid-to-late summer. Plant seeds about 1/2 inch deep and 2-4 inches apart in rows 12-18 inches apart. Once seedlings are established, thin them to 6-8 inches apart to give the developing bulbs ample space to grow without competing for resources.

Watering

Consistent moisture is key for tender, sweet kohlrabi. Irregular watering can lead to tough, woody, or bitter bulbs. Aim for about 1-1.5 inches of water per week, either from rainfall or irrigation. During dry spells, particularly as the bulbs begin to swell, ensure the plants receive regular, deep watering. Mulching around the plants can help retain soil moisture, suppress weeds, and keep soil temperatures more consistent, which kohlrabi appreciates.

Fertilizing

If you've prepared your soil with plenty of compost, your kohlrabi might not need much additional feeding. However, if your soil is less fertile or you notice slow growth, a balanced organic fertilizer can be beneficial. You can apply a granular, all-purpose fertilizer at planting time, or a liquid feed once the plants have developed a few true leaves and again when the bulbs start to form. Avoid excessive nitrogen, as this can encourage leafy growth at the expense of bulb development.

Pruning

Generally, kohlrabi doesn't require much pruning. Some growers prefer to remove a few of the lower, older leaves as the bulb begins to swell, believing it directs more energy to the developing stem. However, be careful not to remove too many, as the leaves are essential for photosynthesis. The main goal is to ensure good air circulation around the plant to prevent fungal issues, so if leaves are very dense, a light thinning might be helpful.

Harvesting

The best time to harvest kohlrabi is when the swollen stem (bulb) is 2-3 inches in diameter. At this size, they are most tender, juicy, and sweet. Larger bulbs can become woody, tough, and less flavorful, though some varieties are bred to grow larger without sacrificing quality. To harvest, simply cut the stem at the soil line with a sharp knife. You can also harvest the young, tender leaves, which are edible and nutritious, similar to collard greens or kale. Enjoy your fresh kohlrabi soon after harvesting for the best taste!

Kohlrabi, often called the 'German turnip' or 'stem turnip,' is a fascinating member of the Brassica oleracea species, which also gives us cabbage, broccoli, cauliflower, kale, and Brussels sprouts. Its journey began in Northern Europe, likely in the German-speaking regions, where it was first documented in the 16th century. Unlike its close relatives, kohlrabi is cultivated for its swollen, turnip-like stem that grows just above the soil line, rather than its leaves, flowers, or roots.

While its exact domestication history isn't as clear-cut as some other crops, it's understood to have evolved through selective breeding from wild cabbage varieties. Early descriptions from European botanists highlight its unique appearance and taste, quickly making it a staple in German cuisine. From there, its popularity spread across Central and Eastern Europe, becoming a common sight in gardens and markets.

Kohlrabi eventually made its way to other parts of the world, including India and parts of Asia, where it's valued for its crisp texture and mild, slightly sweet flavor. It's also found a home in American gardens, particularly among those who appreciate its quick growth and versatility. Despite being a relatively 'young' vegetable in terms of its recorded history compared to some ancient crops, kohlrabi has carved out a distinct niche due to its ease of cultivation and delightful culinary attributes.