To Dig or Not to Dig: When the Dahlia season finally comes to end sometime in late October or early November you will need to decide if you are leaving them in the ground or digging them up. If you have heavy clay soils I would recommend digging them up even if you plant the tubers in the same spot the next year. This is because clay soils hold onto so much water you would be taking a chance on losing some of them to rot. If you choose to leave them in the ground, plan on mulching them with some leaves or compost. After the plants have taken a hit from a good frost and have turned almost black it’s time to cut them back and clean up the area. Cut them back about six to eight inches from the ground and fold the remaining stalk over to keep rain water from settling inside the hollow stalk and potentially causing your tubers to freeze. I know that some people use tin cans to place over the stem during this process. Next, you should mulch and then just wait for them to come up and smile at you next spring.
Washing & Drying Your Tubers
For our washing area, we built a wooden box with a wire mesh bottom. Adjust your water pressure so that it knocks the dirt off your tubers but not so high that it blows off the skin. Also keep in mind that if you wash them in the spring, be careful you don’t blow off the eyes (although they will usually grow back).
Next, allow the tubers to dry out before you begin any dividing or trimming process. Place them in an area where they can get proper air circulation so they dry. If it’s a nice day (not too hot) we leave ours outside and they dry pretty quickly. If you put them in a cool darker place in a box where they sit in the water drippings, after 2 or 3 days, they could begin to mold.
Tubers come in a variety of sizes and shapes. You may choose to divide your tubers individually or by a clump (sections). Look for the eye on the tuber which it will need in order to grow. Some tubers do not have eyes. The eye will be located at the bottom area of the stalk and top of the individual tuber. Sometimes the eye may be hard to find so divide the clump in sections as needed. You can use a dividing knife or garden clippers. Once you cut your tubers, allow the cut area to dry/heal for a day or two before storing or planting. Our storage area is in our basement and we turn on our fans for better air circulation.