Even the best gardeners hesitate to plant Dahlias because they are intimidated by the process of over-wintering the tubers that are left in the fall. It’s easier than you think with a few simple steps, a couple pieces of equipment you probably have on hand, and a little extra effort!
After the first hard frost of the year, your dahlia stalks will turn black in the garden and die off. Cut down the stalks to just above the soil (so you can locate the tuber) and leave them in the ground for another few days.
Using a pitch fork or small fork-like garden tool, gently dig up tuber, shake dirt off without damaging tuber cluster.
Allow tubers to dry for a few days out of direct sunlight. I find it easiest to put the tubers in paper grocery bags that are labeled with the colors /type of flower and put them into a dark basement room. Do not put in an unheated garage, they need to be stored at around 45-55 degrees.
After a few weeks of drying, you can spray dirt off with water and either wrap them individually in saran wrap, or repack lightly in peat moss or vermiculite (found at all hardware and garden stores). Sometimes I just use the dirt I still have in the garden; you just don’t want them to dry out completely. Check periodically throughout the winter to make sure they are not drying out and shriveling. If they are, mist with water.
In spring after date of last frost in your area, plant your tubers! Separate the tubers, using sharp knife or garden snipper, making sure each tuber has an “eye” on it , which is where the new growth will start. If they seem dried out or wilted, discard. The best thing about tubers is when you put one in the ground in spring, by fall harvest time, four or five tubers will have grown, so your garden will be fuller every year!