Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
What is Napa Cabbage?
Napa cabbage (Brassica rapa subsp. Pekinensis) is a cool season annual vegetable that is a member of the cruciferous family. It is related to broccoli, cauliflower and bok choi. Native to China, it is thought to be the result of a cross between turnips and bok choi. The first mention of it is in the 15th century. It then spread to Japan and Korea. In the 19th century, it spread throughout Asia and then into Europe, America and Australia thanks to Chinese immigration to those areas.
Napa cabbage has light green leaves with white veins. It forms an oval shaped head, different from the rounded heads of cabbage. When mature, the plants stand 18 to 20 inches tall and 5 inches wide. The heads are harvested before they bloom. Two conditions cause the plants to bolt, i.e. flower and set seed: very low temperatures and very warm temperatures.
How to Use Napa Cabbage in Cooking
Napa cabbage is very versatile. It is often used in kimchi, a Korean dish that consists of fermented vegetables. It is also used in stir fries, hot pots, soups and as wraps. In Western cuisines, the leaves are eaten raw in salads or cooked.
How to Grow Napa Cabbage
Napa cabbage is a cool season plant that can be grown in the spring or the fall. I like to grow my brassicas in the fall because the spring weather is too unpredictable, especially for this plant. If we have a few days of really cold weather, that will cause the plants to bolt. If it heats up to summer temperatures for a few days, the plants will bolt. The weather is more consistent in the fall with gradually declining temperatures.
Napa cabbage grows in full sun or partial shade. The plants need a minimum of 4 to 5 hours of sunlight per day. They will not grow if they receive less than 4 hours of sunlight each day.
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The best soil for these plants is a rich loamy soil. They will not grow in sandy or clay soil. You can enrich your soil by working in lots of compost or well-rotted manure. In addition to enriching your soil, check the pH. Aim for 6.5 – 7.0. Once the heads start to form, you can give the plants a boost of nutrients with fish emulsion or a balanced fertilizer such as 20-20-20.
Consistent watering is important for napa cabbage. The plants need a steady 1 inch of water per week. Consistent watering is most critical during the period when the heads are forming. Too little water will result in a calcium deficiency that causes the tips of the leaves to turn brown and die. Drip irrigation on a timer is the best way to ensure that your plants are getting consistent moisture. A thick layer of mulch will also help to retain moisture in the soil as well as keep down weeds which would compete with your plants for water and nutrients.
How to Grow Napa Cabbage From Seed
You can direct sow your seeds in your garden in the spring after your last frost date. Plant them ¼ inch deep and 6 inches apart. In the fall, you can sow seeds 6 weeks before your first frost with the same ¼ inch depth and 6 inch spacing. The seeds will germinate quickly, within 3 – 4 days. When the seedlings are about 2 inches tall, thin them to 12 – 18 inches apart. You can add the thinnings to a salad.
You can also start seeds indoors for spring planting 4 – 6 weeks before your first frost. Plant the seeds ¼ inch deep in containers. Germination will be quick, 3 – 4 days. You can plant your seedlings outdoors in your garden after your last frost. Space them 12 – 18 inches apart.
How to Harvest Napa Cabbage
Napa cabbage matures in 70 to 80 days. You can test whether your plants are ready to be harvested by gently squeezing them. A mature head feels firm rather than soft. Use a sharp knife to cut the heads about 1 inch above the soil level. Napa cabbage is an annual and will not grow back for cut and come again harvests.
How to Store Napa Cabbage
Napa cabbage can be stored for up to week in your refrigerator. Place the heads, unwashed, in plastic bags. Store them whole. Do not wash or cut the heads up until you are ready to use them. The added water will cause them to rot.
© 2020 Caren White