Choy Sum

Choy sum is a leafy green member of the cabbage family.
 
Also known as Chinese flowering cabbage, its name means “heart of the vegetable”. It is a common ingredient in Chinese and Japanese recipes, and you can grow it at home.

Choy sum plants (Earth100) CC BY-SA 3.0

Choy sum description
 
Choy sum (Brassica rapa var. parachinensis or Brassica chinensis var. parachinensis) looks a lot like bok choy but has longer stems. It is somewhat more tender than Chinese broccoli, making it an excellent choice for sit-fry. And there is even a purple variety!

Purple choy sum (Earth100) CC BY-SA 3.0

While choy sum can be perennial, it is grown primarily as an annual.
 
Unlike its cousin the cabbage, choy sum does not form a head. Instead, it grows in a loose cluster of leaves with bright yellow flowers. Plants grow 4 to 16 inches (10-40 cm) tall and have a shallow rooting system (4-5 inches deep), making them an excellent choice for container planting. You will want to use containers that are 6-8 inches deep and wide.
 
How to grow choy sum
 
Like other members of the cabbage family, choy sum prefers cooler weather. Temperatures of 55-75°F (13-24°C) are ideal. If you live in an area with hot summers, choy sum makes a nice winter crop. Plus, you can always grow it indoors on a windowsill.
 
Choy sum seeds are contained in siliques. If you’ve ever let radishes go to seed, you’ll know what I mean when I say one plant can lead to a lifetime supply. You can also buy seedlings. [Check out your local farmers market or Master Gardeners plant sale.] If you use seeds, plant them ¼-½“ (.6-1.3 cm) deep and 2” apart. When seedlings are 2-3” tall, thin them 6” apart.
 
Choy sum prefers a soil pH of 5.6-7.5 and at least 4-6 hours of sunlight each day. Feed your choy sum with a balanced fertilizer every 2-3 weeks. These plants grow quickly.
 
Your choy sum should be ready to harvest in 30-50 days, when it is 6-8” (15-20 cm) tall. You can snip off outer leaves as you want them, allowing the inner leaves to continue growing, or harvest the entire plant. Rather than pulling it up by the roots, it is better to cut the plant at or slightly above soil level. This provides important soil microorganisms the food and protection they need to help the next seeds you plant.
 
You can extend your harvest season by planting seeds in succession rather than all at once.
 
Choy sum pests and diseases
 
Aphids, caterpillars, and flea beetles can be managed with insecticidal soap or neem oil, but these plants are generally pest-free. Most diseases associated with choy sum are related to overwatering. Root rots and other fungal diseases, such as Verticillium and Fusarium wilts, can be avoided by watering at ground level and allowing the soil to dry slightly between waterings. Bacterial wilt may also occur.
 
Choy sum is yet another edible plant you can add to your landscape, garden, or balcony. Give it a try today!