If carrots are purchased with their green tops, remove the tops as soon as you get the carrots home, leaving 1 inch/2.5 centimeters of the stem attached. If left attached, the tops draw moisture, flavor, and nutrients from the roots. Store the carrots and tops separately. Put unwashed and untrimmed carrots in a plastic bag lined with a paper towel, which wicks away any trapped moisture and keeps the carrots fresh longer, and refrigerate. They will keep for 3 to 4 weeks. To store the greens, trim off the stem ends and wrap the leafy tops in a paper towel, then seal the towel inside a lock-top plastic bag and put the bag in the refrigerator. For peak freshness, the young green tops should be used within a day or two of purchase.