Answer: While you have the opportunity to purchase them anytime of year, they are at their peak in October to around the start of spring. California is the number 1 producer of sprouts in the United States. It’s their supply that takes us all the way into the spring time. Brussels sprouts from a colder climate, like my home state of Michigan, can only expect to have local sprouts available until just after Thanksgiving.
Brussels sprouts are a cool season crop, that is best planted in the summer for a fall harvest. If you live in any area that experiences frost, then it’s best to let a light frost hit first before picking. This will actually improve the flavor. You can buy them as early as September here in Michigan, but they will be sweeter once the frost hits.
When buying Brussels Sprouts, if you can get them still on the stalk that is your best choice for freshness. You can place the whole stalk into a water pitcher and keep for a while in your fridge.