Q: Last year I signed up for a farm share and discovered a couple of vegetables I hadn’t cooked with before. One of them was napa cabbage, which I loved. This year, my farmer is on hiatus, so I’d like to grow my own. I assumed it was only grown in California, because of the name, but apparently it grows here! Two questions: Is there anything special I need to know about growing it? And, the cabbage we received had lots of tiny holes chewed in them. We had to throw the outer leaves away. Is there a way to prevent that?
A: Napa cabbage is delicious, isn’t it? I like to chop it up and make a salad with peanuts and mint. You can also use it in stir fries or in filling for dumplings. And yes, it will grow in our climate. The name napa is from a Japanese word, not from California’s wine country.
Napa cabbage is a form of Chinese cabbage. Extension recommends growing a variety called Blues, but notes that the Minnesota Landscape Arboretum has also had success with a variety called Rubicon. I know of some Minnesota gardeners who’ve grown nice heads of Rubicon, too.
It can be hard to decide when to plant napa cabbage. It’s a cool-season crop, but if you plant it too early, it can be damaged by frost, causing it to bolt later. Another option is to plant in July and harvest in September, hoping that August won’t be too hot. Plant where you have not recently grown plants in the brassica family, such as broccoli, cabbage or cauliflower.
The damage you’re describing sounds like it was probably done by flea beetles. They are a common garden pest, and they like cabbage, kale, radish leaves and mustards. They destroy my arugula every year. They can damage young plants severely enough to kill them.
Flea beetles are most active in spring, so a July planting may help reduce their damage. A row cover is also a good defense against flea beetles. This is a light fabric, available from garden stores or catalogs, that you lay on top of your plants. It’s important to cover the plants before the flea beetles find them, as soon as they come up or as soon as you set out seedlings. It works, but it’s not foolproof. Still, as you discovered, with napa cabbage it’s typically only the outer leaves that are ruined, and you should still have enough nice inner leaves to make it worth growing.
There’s more information about flea beetles here: extension.umn.edu/yard-and-garden-insects/flea-beetles.
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