Question about dahlias

Question

I’ve started growing dahlias this year. I prepared the ground well rotovating well-rotted manure in, plus old bedding from the chicken house, and my dahlias have been stunning with many family and friends having lovely bunches of flowers. The plants are still producing good flowers but they are starting to get less flowers but still quite a lot to cut. When I picked up my order of rooted cuttings from Gilbert’s dahlia nursery in Romsey in Hampshire, I was told that I could take a few cuttings from the rooted cuttings before they planted out and that is what I did, and they also made good flowering plants. However, my question is: Should I lift my dahlias or leave them in the ground? I do want to take cuttings in the spring so I suppose I will have to lift them in early spring. What I don’t want is to lose any of my dahlias, as there are some very good colours. Any help would be very much appreciated.

Also, I can remember a dahlia called Blue Bonny or it might have been Bonny Blue but I just can’t find it. I would have loved to have had it in my dahlia bed this year. So I’m hoping with your expertise and knowledge you may well put me in touch with a grower. The Eden Project does list it but they told me that they haven’t stocked it for some time and won’t be in the future. So please for next year’s dahlia season, help me find a supplier.

Thanks,
Ralph

Answer 1

Dahlias are reliably winter-hardy only in zones 8 and above, or the equivalent. That means that if your area's winter temperatures get below -10 C at any point during the winter, you should lift them to avoid potential damage. Dig the tubers around the time of the first frost in the fall.

Yes, to use the most common method of propagating dahlias, you will need to lift your dahlias. It is easy to take the cuttings if you already have the tubers in storage for the winter. Here's how:

https://www.gardeningknowhow.com/ornamental/bulbs/dahlia/rooting-dahlia-cuttings.htm

Our site doesn't recommend specific suppliers, but keep an eye out for online gardening retailers who may have the plant again. You could also try asking around gardening clubs in case someone can give you a cutting. I think Bonny Blue is the correct variety name.