All items will ship at the appropriate time for your zone in the spring of 2019.
Dahlias are hardy to USDA Zone 8 where they can be cut back and left in the ground to overwinter. In Zone 7b, dahlias sometimes overwinter in the ground depending on soil drainage and severity of the winter. It is recommended the tuberous roots be lifted and stored during the winter for zones 2-7. After a killing frost, cut the foliage back 2 to 4 inches above the ground. Lift each clump separately with a spading fork. To avoid spearing tuberous roots, begin digging a foot away from the center of the plant. Gently brush soil off the clump of tuberous roots. Spread the clumps in a well-ventilated, shaded area to cure for a few days. Do not leave the tubers in full sun. Dust injured portions with sulfur to inhibit diseases. Pack each clump upside down in a ventilated box or basket using slightly damp vermiculite, perlite, or peat moss to cover the clumps. During the winter, the tuberous roots should be stored between 35 and 50 F and should not be exposed to hot or cold drafts or damp or very dry conditions. If the tuberous roots begin to shrivel during the winter, sprinkle lightly with water.