Su hao kohlrabi Vietnamese cooking uses and container growing tips for Asian home gardeners

Su hao, known as kohlrabi in Western contexts, is a versatile vegetable enjoyed in Vietnamese cuisine. Its unique flavor, a cross between cabbage and turnip, and its crisp texture make it a valuable ingredient. In Vietnam, su hao is commonly used in soups, stir-fries, and as a fresh element in salads and pickles. One of its most popular uses is in canh su hao, a clear, refreshing soup often made with pork or shrimp, where the su hao is peeled and cut into bite-sized pieces and simmered until tender. It also finds its way into món xào, stir-fried dishes, where it adds a delightful crunch. Young, tender leaves and stems can also be eaten, often blanched and served with a dipping sauce. For those in apartments or with limited space, container gardening offers an excellent way to grow su hao.

When growing su hao in containers, select pots that are at least 8-10 inches deep and wide to allow for root development. Ensure the containers have adequate drainage holes to prevent waterlogging, which can lead to root rot. A good quality potting mix that is well-draining is essential. You can amend standard potting soil with perlite or coco coir for improved aeration. Sunlight is crucial; su hao thrives in full sun, so choose a location that receives at least 6-8 hours of direct sunlight daily. Balconies, patios, or sunny windowsills are ideal.

Sowing seeds directly into the container is the most common method. Plant seeds about 1/4 to 1/2 inch deep and space them a few inches apart. Once the seedlings emerge and have a couple of true leaves, thin them to about 6-8 inches apart to give each plant enough space to develop its bulbous stem. Alternatively, you can start seeds indoors 4-6 weeks before the last frost and transplant them into containers once they are sturdy enough.

Watering is key for successful su hao cultivation. Keep the soil consistently moist but not waterlogged. Water thoroughly when the top inch of soil feels dry to the touch. Avoid overhead watering, as this can encourage fungal diseases. Drip irrigation or watering at the base of the plant is recommended. Regular feeding will also promote healthy growth. Use a balanced liquid fertilizer every 2-3 weeks, following the product's instructions.

Pests and diseases can be a concern, even in container gardens. Common pests include aphids and cabbage worms. Regularly inspect your plants for signs of infestation. A strong spray of water can dislodge aphids, and for more persistent issues, insecticidal soap can be used. Cabbage worms can be handpicked or treated with Bt (Bacillus thuringiensis), an organic pesticide. Ensure good air circulation around the plants to help prevent fungal diseases like powdery mildew.

Harvesting su hao is typically done when the bulbous stem reaches about 2-4 inches in diameter. The exact timing depends on the variety and growing conditions, but it usually takes 6-10 weeks from sowing. Gently twist or cut the bulb from the stem. Don't wait too long to harvest, as overgrown su hao can become woody and less palatable. The leaves and smaller side shoots can also be harvested and used in cooking.