Climate Change has disrupted the rhythms of Nature. When I first started growing dahlias our National Capital Dahlia Society scheduled our show for the last weekend in September for fear of a frost. In recent years frosts have come later and we have more opportunities to enjoy the subtle colors of the late season. But some morning soon the plants will be frosted. Here in the Adirondacks we almost had frost last week.
In last year’s Newsletter, we discussed the decision to dig and store the clumps or leave them in the ground. For the casual grower in growing Zone 7 and higher, leaving them in the ground with insulation is a reasonable choice. Cut the stalks almost to ground level and lay on a small hill of leaves or compost. It could be topped with a piece of plastic or fiberglass insulation. If your soil is primarily clay with poor drainage, the risk of rot increases. It has been my experience in Zone 7 that soggy soil is the greater risk. (Photo right and above by Alysia Obina.)
Everyone has their special way of digging and storing dahlia plants. I will dig them when we get home in October, frost or no frost. I believe in the rubric that they can be dug after 120 days in the ground. I store as soon as they are dug and divided. Dip the cutting implements in a 10% bleach solution (or Virkon-S) to avoid passing virus from clump to clump. More info here.
Store the divided clumps with their tag in plastic bags with vermiculite. Make sure you have a piece of stalk connected to each tuber. I mark the bag with the name of the dahlia. I leave the bags open for a few days to see if moisture forms on the bag. The tubers should not give off more moisture than the vermiculite can absorb.
If you want to skip digging and storage, just treat the dahlia as an annual - leave it in the ground, and replace it next spring if it does not winter over. Until you get the dahlia bug don’t be put off by having to dig and store them.
