Dahlias are a favorite among many gardeners for their large and vibrant blooms. They are tender perennials that need to be brought inside during the winter months to be cared for until they can be planted again outside in the spring. While dahlia root structures are regularly referred to as bulbs and even sold as bulbs, they are not true bulbs. They are actually tubers. No matter what you call them, if you properly take care of your dahlia bulbs (tubers) during the winter, you will reap the benefits in the next growing season.
Wait until after the first frost and the foliage has turned brown or black. Then cut back the foliage to about 6 inches above the ground.
Dig up your dahlia bulbs with a garden fork or shovel. Dig a circle around your plants about 6 inches deep, and then pull down on the fork handle to lift the bulbs out of the soil. Shake off the extra soil.
Dry out the bulbs. Choose a dry, well ventilated area and set the bulbs upside down so the excess moisture can drain out of the stems. Drying the bulbs will take about two weeks.
Store the bulbs in an open container full of dry sand or peat moss. Do not add water. You can also store dahlia bulbs by themselves in a sealed, heavy-duty bag (like a lawn bag). Then place the bulbs in a cool, dry location that is between 40 and 45 degrees F. A garage, attic or crawl space may be a good location in your home.
Check on your bulbs every two to three weeks. If you notice any diseased or damaged parts, just cut them off with a knife. If you notice the bulbs shriveling up, set them in water for about 12 hours and dry them out as described in step 3 before storing them again with the others.