The general practice with Dahlia bulbs is to dig them up and store them over winter, particularly in the UK. This helps protect the bulb from freezing temperatures, but when should you dig up dahlia bulbs?
When To Dig Up Dahlia Bulbs?
Wait until your Dahlias have begun to die back before digging up your dahlia tubers. This tends to happen around the middle of Autumn. Alternatively, if a hard frost is forecast earlier in the year than normal then try to dig them up before it arrives.
It will be fairly obvious to you when the foliage starts to die back. They will go quite limp and look fairly unsightly, this is the perfect time to lift your Dahlias.
You want to give them as long as possible to keep gathering energy into their tubers. So it is important not to lift them too early as this may affect how well they perform in the following year.
Conversely, you really don’t want to leave them in the ground too long as if an early, but severe, frost arrives then it could completely kill off your dahlias and they won’t be back at all next year.
Keep an eye on the weather and make sure they are lifted before any frost arrives, even if they haven’t died back yet.
This is even more important for Dahlias grown in pots. Any plant grown in a pot is more susceptible to frost and this is particularly applicable to dahlias.
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.