Whether you add it raw into smoothies, sauté it for an omelet, or bake it into a quiche, spinach is one of those rare, versatile vegetables that's easy to add to any meal for some extra nutrition. But like most salad greens, spinach is fickle, and if you don't store spinach correctly, there's a good chance your spinach will wilt before you have a chance to use it. And you'll definitely know when your spinach has gone bad. The edges of the once bright, crisp green leaves will first turn yellow, and eventually, the leaves will get gnarly and soggy, often taking on an unpleasant smell. At that point, your spinach is better off in the compost pile than on your plate.
So how do you prevent this fate and keep your spinach fresh for as long as possible? By learning how to store your spinach in the fridge correctly. Really, there's not much to it—though there are some different methods that people use.
The main idea behind all of these different storage methods is to keep your spinach as dry as possible, because excess moisture is what causes salad greens to get slimy. But the first step when you get a bag, box, or bunch of spinach is to pick out any leaves that may have already started to turn yellow or look like they've passed their prime. You can then wash the remaining leaves and dry them thoroughly, ideally using a salad spinner or, at minimum, patting them down with paper towels. The trick here, though, is to make sure the greens are really and truly dry before you go ahead and repackage them for storage.
It's only once your spinach leaves are separate, washed, and fully dried that you can store them. Based on their decades of experience working in a test kitchen, the experts at Cook's Illustrated recommend storing salad greens in a salad spinner. As the team explains in The Cook's Illustrated Cookbook: 2,000 Recipes from 20 Years of America's Most Trusted Food Magazine, "For delicate greens, line an empty salad spinner with paper towels. Layer the dried greens in the bowl, covering each layer with additional towels, and refrigerate."
If you don't have a salad spinner (and honestly, if you're this invested in making your greens last, you should probably invest in a salad spinner, too), you can also store your spinach in a hard-sided container that's lined with paper towels. Christine Gallary of The Kitchn found that this method kept salad greens fresh for up to ten days.
You can also freeze spinach if you have more than you think you'll be able to use in a week or so. After rinsing the leaves, pop them in a pot of boiling water for about 30 seconds; this process is called blanching, and, as Bon Appetit explains, this process takes "the raw edge off" before freezing. Take the blanched spinach out of the boiling pot of water and dunk them in ice water to stop the cooking process, then squeeze out the excess water, place the spinach in a plastic bag, and, after removing all the air, put it in the fridge. You'll be able to use that frozen spinach in smoothies, quiches, and omelets—without running the risk of finding spinach slime in your fridge.