Dahlia Bulbs and Tubers: Planting and Care
Dahlia bulbs are the root systems, which consist of tuberous roots, from which the new stems, leaves, and flowers are produced. It is very easy to propagate your dahlias by dividing the tubers of mature plants.
Step 1: Plant the Dahlia Tuber
When buying dahlia tubers, look for large, healthy ones with prominent ‘eyes’, which are small whitish growths, usually found on the upper part of the tuber. The tuber must be firm to the touch, and free of any shriveling, or cuts and scrapes. Plant the tuber in spring, when there is no danger of frost, and the soil is no longer cold. Use a garden fork and shovel to dig out a foot-wide hole, with the same depth. Add mature compost and bonemeal to the soil, and back fill the hole to half. Place the tuber in the hole so that the eye is pointed upwards. Add some more of the soil on top. Wait for the plant to start sprouting before you fill the rest of the hole.
Step 2: Dig up the Dahlia Bulb in Fall
Dahlia tubers are not hardy, and must be adequately protected from winter frost, if you want them to produce blooms again. The best time to dig up the dahlia bulb is in the fall, after the first frost of the season has started affecting the leaves of the plant. If you dig out the tubers any earlier, they may still be green, and susceptible to rot. Leaving them in the ground longer will result in frozen, unusable tubers. Cut the plant down and use a garden fork to dig the soil at a distance of about one foot all around the plant. Dig deeply, to about one foot depth, so that the soil is loose and the plant can easily be pried out.
Step 3: Prepare the Dahlia Bulb for Storage
After you gently dig out the dahlia bulb, carefully remove the excess soil around the tubers. With the garden hose, gently wash the dahlia bulb. It is advisable to divide the tubers before storing them. If you store the whole bulb as it is, you will lose all the tubers if the bulb rots during storage.
Step 4: Divide the Dahlia Bulb
The dahlia bulb consists of several tubers. The plant and flowers are developed from the eyes on the tuber. First, store the healthiest tubers that have eyes. The "mother" tuber is the central tuber from which the plant sprouted this year. It is best discarded, even if it looks healthy and has eyes. Use a sharp, sterilized knife to cut out the tubers. Make sure that each division includes a portion of the stem, with no excess parts that will induce rotting.
Step 5: Store the Tubers
Keep the tubers in a dark, cool, frost-free, ventilated environment. You can keep around six tubers in a pierced plastic bag. Add some peat or shredded paper, which will absorb excess moisture. Keep the bag covered in a container. Regularly check on the tubers for signs of dryness or rotting. Rotting tubers must be promptly discarded. Do not let the tubers dry out and die, a small sprinkling of water is enough to provide required moisture.