The world of dahlias can be intimidating when you first start learning about these beautiful flowers. There are so many different types and classifications.
Here is some information that you might find useful on your journey to growing dahlias. Dahlia petals are called 'florets' and it's how the florets are formed which determines how a bloom is classified. I have used the word petals in this summary to make it more accessible to everyone.
Dahlia types:
Pompon - the smallest of the dahlia types that are about the size of a golf ball. Adorable little round flowers with petals going all the way back to the stem. Petal tips should appear rounded.
Pictured below: Glenbank Honeycomb
Ball - exactly how it sounds. Round, ball shaped blooms with lots of petals which go all the way back to the stem. Petals curl in on themselves forming a tube at the base. These are the longest lasting as a cut flower due to their high petal count and firm shape which is not easily damaged during transport.
Pictured below: Salmon Joy
Decorative - these dahlias have a high petal count with a closed center however the flowers are flatter than a ball form (not as deep). Their form varies a lot as this classification fills the gap between the ball form and the cactus form.
A formal decorative has petals which are flat, neatly arranged and usually have a rounded petal tip.
Pictured below: Florelie Magpie
An informal decorative has petals which are usually curved or wavy with a pointed petal tip.
Pictured below: Carlos Watermelon
There are many other types of dahlias including singles, collerettes, orchid, orchette, anemones, cactus, stellar, waterlily and laciniated /fimbriated. We have focused on the types most commonly used for commercial cut flowers in this post although all dahlias can be used as cut flowers.
For more detailed information about dahlia types visit the Dahlia Society of Victoria website (https://dahliasocietyofvictoria.org.au/Dahlias-for-showing). Information on judging dahlias and the Australian point scoring system used in competitions can also be found there.
We often like to classify and organise things however plants don't always neatly fit into a category so think of these types a bit like a continuum with flowers falling along the spectrum.
Dahlia Sizes:
Dahlias are classified into size groups which are used in dahlia showing competitions.
Pompon - less than 50mm
Miniature - under 120mm
Small - between 120mm - 160mm
Medium - between 160mm - 210mm
Large -between 210mm - 260mm
Giant - above 260mm
The term 'dinnerplate' is often used to refer to big dahlias. This isn't a formal classification but is often used to refer to dahlias that are large or giant in size.
As a cut flower farm we predominantly grow miniature and small sized blooms on the farm with a smaller number of pompons and medium sized blooms. Even dahlias in the 'small category' are quite large compared to other flowers commonly used in floral arrangements. Typically as the flower size increases the vase life decreases.
My sincere thanks to Debra Collett from the Dahlia Society of Victoria for cross checking my information.