A Dahlia Grower’s Perspective on Tubers
As a dahlia grower and retailer here in the UK, I see the same reaction every season. A customer opens their order, looks at the tuber, and their first thought is often: “That’s smaller than I expected.”
It’s completely understandable—here in the UK, we’ve developed a strong preference for big, chunky tubers. They feel reassuring. They look like value for money. They seem like they’ll grow into better plants.
But after years of growing, dividing, and selling dahlias, I can tell you with confidence:
The size of the tuber when it arrives has very little to do with how the plant will perform.
What Makes a Tuber Viable
The most important thing to understand is this: a dahlia tuber is only a storage organ. Its job is to get the plant started—not to determine its future.
For a tuber to be viable, it needs:
- A growth eye (or the ability to produce one)
- An intact neck
- Healthy, firm tissue
And here’s a point that often gets misunderstood:
If a tuber is still connected to the neck, it is viable—even if it looks broken, rough, or imperfect.
I regularly handle tubers that look snapped, bent, or a bit scruffy. As long as that connection to the neck is intact, the tuber can still do its job. It may not win any beauty contests, but it will grow perfectly well.
Genetics: Why Size Varies So Much
One of the biggest reasons tuber size varies is simply genetics.
Some varieties naturally produce large, chunky tubers. Others produce thin, wiry ones—sometimes no thicker than a pencil. That’s not a flaw; it’s just how that variety grows.
Dahlias are also genetically complex. They are octoploid, with eight sets of chromosomes, which creates huge variation—not just in flowers, but in tuber shape and size too. Billions of variations.
So a small or slender tuber is often exactly what that variety is meant to produce.
Growth: Small vs Large Tubers
Once planted, the tuber’s role is short-lived. It provides initial energy, but very quickly the plant takes over—producing its own energy and roots.
Given the same care, a small tuber and a large tuber of the same variety will:
- Grow to the same height
- Produce the same number of stems
- Deliver the same flowers
The end result is driven by genetics and growing conditions—not the size of the tuber.
Value for Money
It’s natural to associate size with value. A bigger tuber feels like you’re getting more for your money.
But in reality:
You’re buying the variety, not the size of the tuber.
A small tuber will produce the same plant, the same flowers, and the same overall performance as a large one of the same variety. The price reflects the genetics and the cultivar—not the bulk of the tuber itself.
Key Takeaways
To finish, here are the points I always want customers to remember:
- Size doesn’t matter
A small tuber will grow just as well as a large one. - Thin tubers are normal
Some varieties naturally produce slender, wiry tubers—this is genetics, not poor quality. - Dry or slightly shrivelled tubers can still grow
As long as they are not completely desiccated and still have a viable connection, they will rehydrate and perform. - Broken-looking tubers are often still viable
If the tuber is still attached to the neck, it can grow—even if it looks rough. - But broken necks are a problem
If the neck is completely snapped and the tuber is no longer connected, it will not grow.
Dahlias don’t reward how a tuber looks when it arrives—they reward how it’s grown.
So don’t judge it in your hand. Judge it by what it becomes.