In Northern Virginia we tend to get some warmer days in February that turn our thoughts to tubers. Today it was in the 60s and I could not resist opening a bag of divided tubers. The tubers were firm, the stems a bit dry, but no eyes (shoots). I sprayed a little water on the tubers and vermiculite, but I did not close the bag. Over the next several weeks I will open about 40 other bags, check the tubers, look for eyes, and add a spray of water. I am not certain that the moisture is actually helpful because the eyes will receive all their nourishment from the tuber.
Even after the sprout forms, the tuber typically will not develop rootlets for weeks. I have found no serious science about what wakes up the tuber. (There are plant hormones such as auxin that stimulate growth. I have not yet found the trigger. Occasionally I have had tuber rot in a bag, and the remaining tubers sprouted eyes. Another idea comes from those who force dahlias to grow out of season by a combination of temperature and light. In my imagination I think it is the change of seasons.)
Eventually you will begin to see eyes, and the eyes will develop shoots and then leaves. Move the tuber from its container to a 4–8 inch pot. Now it is time to treat the dahlia as a plant: Water it modestly and put it under lights or on a sunny windowsill, or outdoors. If there is a threat of frost, move any pots outside to the inside for the night.
