Starting Dahlia Tubers is always exciting in late spring but can be quite a task, so I am now using a different method from the video below, which saves time, plastic pots and lots of compost.
Over the years I have accumulated quite a collection of Dahlias and I am particularly fond of the open centre type because the bees and butterflies just love them.
living in Cumberland where it is wet and winter temperatures can dip as low as -10 or even -18 degrees, means that Dahlias must be lifted every year before the frosts.
Tubers are gently brushed clean, checked for any squishy or damaged pieces which are then removed and stored in a cool dark place, packed in wooden crates and old paper.
Fast forward to Spring and attention turns to starting off the tubers again before planting out after the last frosts, which in Cumberland is about mid May.
In previous years, the tubers were thoroughly checked, split and potted on but there comes a time when this can really take over precious greenhouse space, not to mention the cost of potting compost.
Last year, I waited until the last week in April and started the tubers using the tray method. Once leaves and roots developed three weeks later, they went straight outside into their growing place and it worked a treat. These plants will be smaller though, so slug protection is vital.
I did pot a few up to use as spot plants when those bare spaces appear and to give to friends.
Can tubers be planted directly outside?
The short answer is yes but there must be no risk of frost as even a touch below zero will render the tubers to a mushy mess.
However, if you are splitting large tuber clusters, the tray method allows you to instantly see any that fail to sprout.
Why split the tuber cluster?
A healthy Dahlia plant requires no more than about four or five stems coming form the tubers, so large clusters can drain a plant of energy very rapidly.
Some Dahlia tuber clusters grow quite large, spanning about 20cm and these would require very large holes to be dug which is often not achievable in a mixed border or planter situation.
The main reason to split tubers is to make even more plants for free, especially true if you have a colour or variety that you are particularly fond of.
How to start Dahlias
In the video below, Laura from Garden Answer clearly explains each stage of the process with in depth description of how to recognise a viable tuber and split the cluster to increase stock and create healthy plants.
Once the tubers have been started in trays, you can pot on or plant directly outside once risk of frost has passed.
Good Dahlia Suppliers in the UK
This list is created from my personal buying experience, there are many more suppliers and of course Dahlias are so easy and quick to grow from seed but these tend to be mixed colours rather then specific varieties.