Our first frost came earlier than usual this year on Nov 2, normally it is Nov 15 or after. So our Dahlias are now a thing of the past, but boy they were wonderful for the month of October!
As beautiful as they are my problem with Dahlias is they need some kind of attention most of the growing season keeping them in tip top shape for when the flowers really get going. They start blooming in summer but the flowers just do not last long in the vase no matter what we do when growing under those stressful conditions. All this leads me to want to yank them out by August because I am tired of cutting and mulching the pathways with their blossoms. Then October comes:
Our Dahlia care: We are in zone 7, southeastern Virginia and we leave our Dahlias tubers in the ground over winter. I am pretty sure I would not grow them if I had to dig every year!
In has been my experience that good drainage is perhaps the most important condition needed. The winter tends to be wetter and the tubers will rot. We keep them mulched year round and may add more in fall/winter if needed. If you want to dig and divide or move now is the time after the frost has killed the top growth.
We found spraying our Dahlias with compost tea at least monthly and weekly preferred gave amazing disease and pest resistance and amazing growth.
As winter is setting in here I am still starting seeds and planting (more Snaps, Dianthus, and Ammi- I have to stop ordering new varieties!) Can’t wait for spring.