Hello hello, and welcome from a distinctly cooler South Cotswolds! We hit 3.6°C overnight on Wednesday here on the flower farm, which has me slightly edgy about when our first frost will arrive. Thankfully, the forecast is bouncing back to around 11°C overnight, a week’s respite before winter creeps closer.
I’m not quite ready to stop cutting yet and there’s still so much cataloguing to do. This is when I really get to observe the dahlias: Are they still healthy? Which ones are showing weakness? How are the new variety trials performing?
I take copious notes and photos as part of our ongoing dahlia variety trials here at The Tetbury Flower Company.
The Magic of Saving Dahlia Seed
As the autumn light softens, your dahlias will begin to change character. Flowers that once opened in perfect symmetry now fade, petals curling inward before falling away. In their place, you’ll see a small green pod forming — that’s the seed head, and inside are hundreds of potential new plants.
Collecting dahlia seed is one of the most magical late-season jobs — and it’s having a real moment. Instagram is full of growers discovering the joy of growing dahlias from seed. Every seedling is a surprise: some wild, some wobbly, and occasionally, something extraordinary.
1. How Dahlias Make Seed
Dahlias are insect-pollinated, meaning bees carry pollen from one bloom to another. Once pollination occurs, petals wither and drop, and the seed head swells and ripens in their place.
Not every flower produces seed.
Tightly packed ball and pompon types often set little seed because their pollen parts are hidden deep inside. Open-centred types (singles, anemones, collarettes, and some waterlilies) are best for beginners.
If you’re keen to collect seed from ball or pompon dahlias, mark those that have clearly been pollinated so you can track them later.
Cornel Brons ball dahlia pollinated vs not pollinated:
2. Cross-Pollination: What You’ll Get
Because bees are free agents, genetics are a jumble. A bee might visit deep red Arabian Night, then your blush Sweet Natalie, and the resulting seedling could be plum, mauve, or an unexpected gem.
Below is a first year seedling out of our own Cotswold Salmon dahlia which has got a bit of love over on my Instagram page
If you want control, you can hand-pollinate: remove petals, dust pollen from one parent onto another, and cover the bloom with a gauze bag to prevent further visits. I do this for specific crosses between certain waterlily types.
For most of us though, half the fun is letting the bees surprise us.
3. When and How to Harvest Dahlia Seed Heads
By this stage of the season, heavy dew and cooler nights make it hard to find a fully dry seed head here in the UK. If left on the plant, seed heads often rot before they ripen, especially in damp climates. Below a rotted seed head vs a great seed head:
But don’t worry, you can harvest earlier. Look for seed heads that are fully conical, not round like buds. Cut the stem around 4 inches long.
Here’s my tried-and-tested method (over 10 years of good yields!):
- Place cut stems in a bud vase or jam jar of water on a warm windowsill.
- Leave until the water evaporates — about two weeks.
- When the stems are brittle and brown, snip off the seed heads.
- Store in an open container (like a takeaway box) with no lid, so air can circulate.
Patience pays off - do let them dry fully before extracting the seeds.
4. How to Extract Dahlia Seeds
When the heads are crisp and dry, crumble them gently between your fingers over a tray or sheet of paper. Amongst the chaff, you’ll find little dark, flat seeds, they look a bit like tiny arrowheads or the cross section of an avocado:
Pick out the plumpest, darkest seeds - these are most likely to germinate.
Pro tip: store your seeds in gauze bags like the ones I get off Amazon, clearly labelled by mother plant.
You will not remember in spring which was which, trust me!
5. Growing Dahlias from Your Own Seed
In February or March, sow your saved seed indoors just like annuals:
- Use fine seed compost
- Cover lightly with vermiculite
- Keep at 18–20°C for 7–14 days
Once seedlings have two true leaves, prick them out into individual pots. By late spring, you’ll have strong young plants ready to harden off and plant outdoors.
Below is my dahlia seedling bed from last year, planted out in June 2024.
Each one will be unique; some tall, some compact, all utterly yours.
If you find a gem, save the tuber or take cuttings next year. That’s how every named dahlia variety began: one special seedling worth keeping.
6. Naming Your Own Dahlia
If one of your seedlings stops you in your tracks, you can absolutely name it! That’s how most dahlias in the world began.
But remember: you don’t “own” the name or the plant unless you register it formally. In the UK, plant names aren’t protected unless you apply for Plant Breeder’s Rights (PBR) — a complex and expensive process, mostly used by large-scale breeders.
For most of us, it’s enough just to grow, share, and enjoy.
Common Questions About Dahlia Seed Saving
Can I grow seed from any dahlia?
Yes, but tight ball or pompon types may not produce much viable seed.
Will seedlings look like the parent?
Almost never. Each seedling is genetically unique, like siblings in a family.
Can I still take cuttings or keep tubers?
Absolutely. Seed collecting complements those methods, not replaces them.
Can I share my seed?
Yes, but be sure to label it as “mixed parentage” and don’t sell it under a named variety.
Recommended Reading about Taking Seed from Dahlias
When I first started, I knew nothing — until I found Kristine Albrecht’s brilliant book “Dahlia Breeding for the Farmer-Florist” (Santa Cruz Dahlias). You can find it on Amazon. It is a must-read if you’re interested in dahlia hybridisation.
If All This Sounds Like Too Much Effort…
…then take heart! We’re doing the hard work for you.
We’re currently ramping up our seed collection here at The Tetbury Flower Company, gathering seed from our favourite varieties to create beautiful mixed dahlia seed packs — including ball, decorative, and waterlily forms.
They’ll be available in our online shop around Christmas, perfect for sowing in early spring or gifting to the dahlia-lover in your life.
Happy seed saving!
Rachel
The Tetbury Flower Company – South Cotswolds Dahlia Specialists
