You probably already know that the main way people grow dahlias is from tubers (those chunky, potato-like roots you plant in spring).
But dahlias also produce seeds which can be planted out to form new dahlia varieties.
You even get to name them if you discover one that’s worth keeping!
This is how to save dahlia seeds from your favorite dahlias.
Ready to grow your own dahlias? Learn my sprouting method in my post on how to grow dahlias from seed.
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Why Save Dahlia Seeds
Dahlia seeds are worth saving for a number of reasons.
- To discover new dahlia varieties and unique flowers
- To fill a garden with dahlias for a low cost
- To avoid disease
- For earlier blooms
- For easy storage
- For more open-centered flowers to feed pollinators
I also grow them just for the fun of it.
And if you clicked on this post, I’m willing to bet you’d find it fun, too!
Want to grow your favorite zinnias over and over each year for free? Learn to save zinnia seeds in this post.
What Do Dahlia Seeds Look Like?
Before you can save seeds, you need to know what you’re looking for.
After a dahlia bloom fades, the base of the flower (the calyx) begins to swell and dry down.
This is the seed head.
It looks like a small, papery, greenish-brown cone, about the size of a large grape when fully formed.
I think ripe dahlia seed heads look somewhat like enlongated buds. Dead dahlia flowers that haven’t been pollinated look more like this.
If in doubt, open up the flower head anyway! It doesn’t hurt to check for seeds when the flower is already dead.
Inside that seed head are individual seeds. (I thought I had a picture of this myself, but I can’t for the life of me find it, so enjoy this stock photo for now!)
Dahlia seeds are flat and oblong, usually tan to dark brown, and roughly the size of a cucumber seed, though smaller varieties produce smaller seeds.
They have a slightly papery texture and a pointed end.
Viable seeds are plump and hard.
Opening up your first seed head is a fun surprise. Some flowers will have lots of seeds, and some will have just a few.
Expect plenty of chaff to fall out and blow away.
The dahlia seeds are heavier and will fall to the table.
One important note: not every dahlia will produce seeds, and not every seed head will contain viable seeds.
Highly doubled varieties (like dinner plates or ball dahlias) tend to produce fewer seeds because the extra petals leave less room for the reproductive parts of the flower. Single and collarette types are the most reliable seed producers.
When Are Dahlia Seeds Ready to Harvest?
Timing matters here. Harvest too early and the seeds won’t be viable. Wait too long after a frost and the seed heads can rot on the plant.
You want to harvest seed heads that are:
- Fully dried and papery — they should feel dry and crinkly, not green or fleshy
- Brown all the way through — a still-greenish calyx means the seeds aren’t finished maturing
- Easy to pull apart — a ripe seed head will open easily and the seeds will fall out
TIP: Dahlia seed heads can be juicy and take a long while to dry out. So, you’ve got to milk them!
To do this, remove any dead petals from the flower. Grasp the closed seed head near the base where it meets the stem and gently squeeze in an upward motion, kind of like squeezing toothpaste out of a tube. The liquid inside should come out the top of the seed head.
Repeat until water stops coming out.
In most climates, this falls in late September through October.
If a hard frost is coming before your seed heads are fully dry, you can cut the stems and bring them indoors to finish drying.
Just lay them out on a paper towel or hang them upside down in a warm, dry spot for a week or two.
It’s also important to note here that you’ll have to stop deadheading dahlias well before your first frost so that the flowers have enough time to be pollinated and form seeds.
My first frost is around October 10. I let certain dahlias go to seed at the beginning of September.
How to Collect and Save Dahlia Seeds
Once your seed heads are dry, here’s how to harvest them:
What you’ll need:
- Small paper envelopes or paper bags (one per variety)
- A dry surface to work on
- A marker or label for each envelope
Steps:
- Cut the seed head from the plant and bring it inside to a dry, clean surface.
- Gently pull the seed head apart. It should open easily. Inside you’ll find the seeds arranged in rows.
- Remove the seeds and spread them out in a single layer to check for any that look shriveled, flat, or obviously undeveloped. Discard those.
- Let them dry for another week at room temperature before storing. Even seeds from a dry-looking head can still have some moisture in them.
- Store in a labeled paper envelope in a cool, dark, dry place. A cool room, an unheated closet, or a garage (in a climate without extreme cold) all work well. Avoid plastic bags, which can trap moisture.
You can be as detailed or casual about labeling your dahlias as you want.
I typically include the name of the parent plant and the year the seeds were harvested. My best flowers were from Cornel Bronze in 2024. I shortened this to CB24.
I didn’t save seeds from those plants, but if I had, I’d probably name them CB24g1 (Cornel Bronze 2024 generation 1).
I haven’t found any generation 1 dahlias that were worth saving seeds from, and since I still plant tubers for named varieties, I just harvest fresh seed from them each year to grow out.
Dahlia seeds stored this way should remain viable for 2–3 years, though germination rates will be highest in the first season.
How long do seeds last? Learn more about seed viability and how to properly store seeds for years in this post.
Breeding New Dahlia Varieties
Dahlias are exciting to grow from seed because the results can be so diverse. Color, shape, and size may be similar to the parent plant, but isn’t guaranteed.
This makes it more difficult to get a certain color or shape just by growing dahlia seeds at home.
Dahlia breeders like Kristine Albrecht, Paul Bloomquist, and Ted and Margaret Kennedy have produced amazing dahlia varieties through years of meticulous cross-breeding and trialing.
I have barely scratched the surface of dahlia breeding and am in awe of the work these professionals do.
My tip for you if you’re just casually saving seeds is to plant similar forms (ball, waterlily, etc.) together and save the seeds just from your favorites. Or vice versa with your favorite color.
Learning to hand pollinate dahlias can get you even closer to the color or shape you desire.
If you want to learn more about this topic, I’d suggest reading Dahlia Breeding for the Farmer-Florist and the Home Gardener by Kristine Albrecht.
It covers the same info in this post in much more depth, plus pollination strategies and dahlia genetics.
Final Thoughts
Each year my most floriferous dahlias were almost always the ones I grew from seed.
I am amazed by how different, unique, and beautiful my seed-grown dahlias are every time I grow them. I feel a sense of pride planting dahlia seeds that I’ve saved from a previous year.
Growing dahlias from seed adds to my understanding of dahlias—how they grow, what they like, what they can tolerate, and how productive and beautiful they can be when they are happy.
If you’ve been growing dahlias for a while and haven’t tried saving seeds yet, this is the year to start.
Who knows? A little time spent harvesting this year’s seeds could turn into next year’s favorite flowers.