Any time is a good time to shop at local businesses. Spending money with locally owned businesses keeps more of each dollar spent within the local community, where the money can be spent again.
But the coming of spring and the opening of local farmers' markets is an especially good time to shop local. Locally grown foods are generally more nutritious and better tasting than ones shipped long distances. It's still early for fruits and vegetables, but local farmers markets will be full of bedding plants this weekend.
If you haven't been to one, give it a try. But get there early. The good stuff goes fast.