Tulips have bulbous underground root structures, and, even though they are considered hardy, they do need some care to maintain their health. Tulip bulbs are best planted in the fall in most planting zones, and, if they are not planted immediately, they need to be safely stored in the meantime. In addition, in colder zones, tulip bulbs need to be preserved during the winter months and planted again in early spring.
Allow the foliage to turn yellow before cutting it back. It can be tempting to cut back the green foliage once the tulips have bloomed, but in order to preserve the integrity of your bulbs, you must allow them to continue to absorb sunlight, convert it into sugar and store the sugar in the bulbs for next year's plants.
Mulch over your tulip bulbs before winter. This is the best way to preserve your tulip bulbs if they are in they planted outdoors in U.S. Department of Agriculture hardiness zones 3 to 7. Use a couple of inches of mulch, such as bark or pine needles. On the other hand, in slightly warmer zones, tulips should be planted in partial shady areas to keep them cooler in the winter months. Tulips typically do not grow outdoors in subtropical or tropical zones.
Dig up tulip bulbs that are in hardiness zones 1 and 2. Some gardeners dig up their tulip bulbs in other zones as well for various reasons, including to keep them from animals or because they are expecting a colder than usual winter. Carefully dig your bulbs, which are typically planted 4 to 6 inches below the soil's surface. Dig wide and low so you do not damage your bulbs.
Store all unplanted bulbs and bulbs that have been dug up in a cool (40 to 50 degrees F), dry location, such as a garage, attic or even the refrigerator--keep the fruit in the crisper because some fruits can sterilize the tulips. Bury the bulbs in some slightly damp peat moss in an open container. Check on the bulbs every couple of weeks to be sure the peat moss is still moist. Throw out any bulbs that have rotted.