Storing Bunch Greens
This category includes vegetables like kale, chard, collards, and bok choy. They're hardier than leafy greens, but they still need a little TLC to stay fresh.
They do best when you remove the rubber band or tie holding them together before you store them. Then wrap them in paper towels and put them in a resealable bag in the fridge. It'll keep them good for at least a week, up to two. If you're not going to use your hardier greens within, say, 10 days, you can also freeze them.
The best way to do that is to give them a quick blanch first. Blanching does a couple of useful things: It stops enzyme activities that can lead to the loss of flavor and texture, and it also cleans the leaves of any lurking dirt and organisms. Here's how you do it: Wash the leaves thoroughly, trim away the woodier stems for greens like kale, where the stems can be fibrous and unpleasant to eat, and then submerge them in a pot of boiling water for one minute. Use tongs or a spider to transfer them to a bowl of ice water for a brief dunk, dry them really thoroughly (a salad spinner works great here), and freeze them flat on a baking sheet to keep the leaves separated instead of in a big clump. Or freeze them in a big clump — that works, too. Once they've frozen completely, transfer them to a freezer bag and store them in the freezer for six to eight months. You can put the frozen greens directly into soups, stews, or smoothies without defrosting them first.