Based on the prevailing climatic conditions, you should consider caring for dahlia bulbs. For example, it is grown as a perennial plant in zone 8 or other warmer areas and leaving the bulbs all year in garden soil is not an issue. However, for colder climates, storing of dahlia bulbs in winter is a necessity to prevent root damage.
Otherwise, frosting and low temperature kills the plants and their roots, if they are not stored in warm indoor conditions. In general, dahlia bulb storage is done during fall for next spring plantation. Discussed below is the step-by-step preparation of dahlia tubers for winter storage:
Ideal Time to Start
So, when to dig up soil for dahlia tuber storage? For most gardening enthusiasts, the perfect time to do this is during fall, shortly after frosting. Allow the top plant portion to die off by exposing them to frost. As the leaves and stem turn black and die, wait for about a weeks time and cut back the stem to about 5 - 6 inch from the soil before digging.
Make sure you do it gently to avoid injuring the fleshy bulbs. Unnecessary damage increases chances of disease infestation during storage. Then, hold the bottom of the stem and lift up the clump along with adhering soil.
Cleaning Dahlia Bulbs
The main stem should be retained with the clump while cleaning and storing dahlia bulbs. Brush off adhering soil from the bulbs and rinse them with a garden hose, while keeping the skin intact. Or else, you can place them in a mesh bag and wash under a shower head. This will remove dust and dirt without damaging the outer skin of the bulbs.
Dividing and Curing the Bulbs
Use a sharp knife or clippers to divide the dahlia tubers (each having a prominent eye). Ensure that you retain 2-inch stem in each of them. To air dry, cut dahlia tubers, arrange them in a newspaper in one layer, and place them in a corner, away from direct sunlight. Maintain room temperature and leave the tubers for 2 - 3 days for complete drying.
Storing the Bulbs
The next step is treating the bulbs with insecticide and fungicide mixture. You can use sulfur powder to dust the tubers. For storing, place the dahlia tubers in a clean nursery flat lined with paper or cardboard box. Then, store them in a cool and dry place till spring.