It is well known that Dahlias don’t like the cold, but how cold is cold? What temperatures can dahlias tolerate before they start to die?
How Cold Can Dahlias Tolerate?
So as long as the weather isn’t freezing then it doesn’t really matter how cold it gets. As soon as there is any frost though the foliage will die off.
Then a heavy frost, where it gets down to -4 or below will kill the tubers. This has to be a big frost as it has to freeze the ground all the way down to the tubers to kill them.
So when the season is coming to an end keep an eye on the weather forecast and make sure to lift your tubers before the first real frost of the winter.
Lifting and Storing Dahlias
If you are going to dig your Dahlia tubers up and store them over winter then follow my quick guide below to ensure you give them the best chance possible.
To begin with, you will want to cut the foliage back almost to the base of the plant.
Once this is done gently lift them using a garden fork. You want to dig well away from the plant, to begin with, to make sure you don’t accidentally stick your fork through the tuber.
Remove any soil from the tuber by giving it a good shake and also a quick brush with your hands. I then like to leave the tubers in the sun for a few hours to dry out.
If the weather is poor then move them into a greenhouse or put them on a windowsill for a while to dry.
You then want to hang them upside down for a couple of weeks to make sure they are really dried out. Now, this obviously needs to be done in a frost-free place as the tubers are really vulnerable at this point.
If an early frost is forecast then you may want to consider bringing them inside.
After a couple of weeks of hanging, they will be ready for their winter hibernation. Wrap them in one or two sheets of newspaper before storing them over winter. You want a frost-free spot but one that also has decent ventilation.
A garage shed or greenhouse is usually a good idea. (depending on the weather greenhouses can get a little chilly so this really depends on your location and the weather that winter)
Leaving Dahlias In The Ground
If you have a smaller garden and no greenhouse or garage in which to store your Dahlias then it may be better for you to leave them in the ground.
This is also true for gardeners who want to enjoy Dahlias but just don’t have the time to dedicate to digging them all up and planting them all over again next year.
To start with you want to remove all vegetation from the plant right back to the base. Use some good secateurs for this as Dahlias can have tough almost woody stems.
You then want to apply a really thick mulch on top of your Dahlias, this is the secret to protecting them over winter.
You can use compost, leaf mould, bark, anything really as a mulch just make sure it is really thick. This should help prevent the ground underneath from freezing which will, in turn, protect your dahlias.
More on Dahlias
Dahlias are simply stunning summer flowers, the pop pop head produces amazing displays. The plant is a member of the Asteraceae family along with daisies, asters and marigolds.
Usually grown from a tuber but they can also be grown from seed. The tubers require special care over winter here in the UK and many growers end up with an almost fanatical devotion to their dahlias.
Despite being unable to survive winter outdoors in most of the UK, they thrive in our summer conditions. The moderate but wet climate we have is absolutely perfect for them.
Dahlias make the perfect container flower and are commonly grown this way. Growing them in containers also makes preserving the tuber over winter a lot easier.