Dahlias are an enjoyable asset to any summer flower garden. Dahlia blossoms can be from 4 to 10 inches wide with multiple petals. The flowering plants are grown from seeds or tubers which are often mistakenly referred to as bulbs. Flower tubers have eyes exactly like a potato does. The tubers of a dahlia can be dug up each year and stored over the winter for planting again the following summer.
It is important to let the plant die naturally on the stalk. If you must cut down the greenery of the plant, cut the stalk at 6 inches high. When the first frost hits your growing area let the plant sit for one to two weeks while the soil's nutritional benefits and energy are focused in the remaining plant. This time allows the tubers to grow new sprouts.
Dig into the flower bed with a pitchfork to loosen the soil around the dahlia root system. Gently lift up on the plant while continuing to prod under it with the fork. Grasp the stem and lift the tuber mass away from the hole. Set it on a cardboard box top or sheets of newspaper in your wheelbarrow.
The tuber of a harvested dahlia plant will have a clump of healthy new growth or tuber sprouts. You can choose to divide the tubers after harvest time or wait until planting time in the spring. To divide tubers you need to have a sharp knife. Look for the eye on each tuber which looks like the eyes on a potato. A tuber can only produce a new plant from an eye. Divide each dahlia clump into halves or quarters by cutting into it with the sharp knife. Let the cut portion dry overnight before you prepare them for storage or spring planting.
Dahlia tubers should be stored in a crate or cardboard box. Gather newspapers and storage medium, which can be peat moss, vermiculite, sand and pet bedding in the form of sawdust or wood shavings.
Dampen the storage medium with a light spray of water. When you squeeze the damp medium it will form into a ball yet no moisture will leak from the mass. Peat moss is packaged as a damp medium so will need no further moisture.
Tuber Storage Preparation
Cover the bottom of the storage container with newspaper that has no colored pages in it. Coat the paper with a 3- to 5-inch layer of the storage medium. Place a layer of tubers on top of the medium. Add a second layer of the medium over the tubers. Continue layering tubers and medium until the medium is close to the top of the container. Top the medium with several pieces of newspaper. Store the container in a cool dry area that has a consistent temperature between 40 and 50 degrees for the winter. Check the tubers once a month until planting time. If the tubers are wrinkly or shriveled they are too warm. A cold storage area will cause the tubers to rot.