An easy, joyful way to discover your own unicorn varieties.
Growing dahlias from seed is one of the most exciting parts of flower growing — a blend of science, surprise, and pure magic. Unlike tuber-grown dahlias, which produce identical plants year after year, dahlias grown from seed are genetically unique. Every single seed holds the potential for a brand-new variety. You may grow a workhorse. You may grow a unicorn. And that is the beauty of it.
Below is a simple, reliable guide to help you successfully start dahlias from seed, whether you’re brand new to growing or adding seedlings to expand your patch.
Why Grow Dahlias From Seed?
Dahlias from seed offer benefits you can’t get from tubers:
-
Affordability: An easy way to expand your garden or field without investing in high-priced tubers.
-
Genetic diversity: Every seedling is a new variety. You might find something exceptional.
-
Early blooms: Seed-grown dahlias often flower earlier than those started from tubers.
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Better adaptation: Seedlings tend to be vigorous and resilient, adapting beautifully to your soil and climate.
- If you’ve been hunting elusive, expensive unicorn dahlias — growing from seed is how you create your own.
When to Start Seeds
Start your dahlia seeds 6–8 weeks before your last frost date.
For most growers in the U.S., that means:
-
Late February through April, depending on your zone.
You can also direct sow after danger of frost has passed, but indoor seed starting gives stronger, more predictable results.
What You’ll Need
- Seed-starting trays or small pots
- High-quality seed-starting mix
- A humidity dome (optional but helpful)
- Grow lights or a bright window
- Labels (you’ll want to keep track as they grow!)
- Dahlia seeds (40 or 100 count available through Ribier Gardens)
How to Start Dahlia Seeds Indoors
1. Fill Your Trays
Use a fine-textured seed-starting mix — light, airy, and moisture-retentive. Avoid heavy potting soil.
2. Sow Your Seeds Shallowly
Place each seed on the surface and gently press it into the soil.
Cover lightly with ⅛" of soil — dahlias need light to germinate.
3. Water Gently
Moisten the soil with a mist or bottom water to avoid displacing seeds.
Keep the soil consistently damp (never soggy).
4. Provide Warmth
Dahlia seeds germinate best at 70–75°F.
With consistent warmth, expect sprouts in 5–10 days.
5. Move Them Into Light
Once sprouted, seedlings need 12–14 hours of bright light daily.
Grow lights placed a few inches above the foliage prevent leggy growth.
6. Pot Up When Needed
When seedlings develop their second set of true leaves, transplant them into 3–4" pots.
This gives the roots space to develop and makes them easier to harden off later.
Hardening Off
About 7–10 days before planting out, begin hardening off:
- Day 1–2: Shade or dappled light for a few hours
- Day 3–5: A bit more sun, a bit more time
- Day 6–10: Full sun, wind exposure, cool evenings
Never skip this step — it sets them up for strong garden performance.
Planting Dahlias Outdoors
Plant seedlings outside once all danger of frost has passed and soil has warmed.
Spacing:
12–18 inches apart, depending on your style of growing.
Soil:
Rich, well-drained, and amended with compost if available.
Ribier Gardens follows no-till, biologically alive soil practices — dahlias thrive in that kind of living system.
Depth:
Plant them at the same depth they were in their pots.
After a few weeks in the field or garden, seedlings will establish quickly and begin forming small tubers underground — which you can lift and save in the fall.
Watering & Care
- Keep evenly moist while young; deep, less frequent watering once established.
- Pinch the growing tip at 10–12" tall for bushier plants and more blooms.
- Provide support (stakes or netting) if you expect tall varieties.
- Fertilize lightly — too much nitrogen leads to lush foliage and fewer blooms.
Bloom Time & What to Expect
Seed-grown dahlias typically bloom 75–90 days from transplanting — often sooner than tuber-grown plants.
And here’s the best part:
You won’t know what you have until it blooms.
Expect:
- Surprises
- Unique color palettes
- New forms
- Flowers you could name
- Some you’ll keep, some you’ll compost
- And possibly… the next Café au Lait-level beauty
That’s the joy and the adventure of growing from seed.
Saving Tubers From Seedlings
At the end of the season, each seed-grown plant will have formed its own tuber clump.
- Cut the plant back after frost
- Let the tubers cure for a few days
- Store them just like any other dahlia tuber
You now have a brand-new variety to grow for years — one you grew yourself from a single seed.
Final Thoughts
Growing dahlias from seed is accessible, rewarding, and full of possibility. Whether you're adding inexpensive volume to your garden or hunting for your own unicorn, these seedlings are where magic happens.
If you’re ready to try, you can find Ribier’s 40-seed and 100-seed packets in the shop — and we can’t wait to see what you discover.
How to Grow Dahlias From Seed
An easy, joyful way to discover your own unicorn varieties.
Growing dahlias from seed is one of the most exciting parts of flower growing — a blend of science, surprise, and pure magic. Unlike tuber-grown dahlias, which produce identical plants year after year, dahlias grown from seed are genetically unique. Every single seed holds the potential for a brand-new variety. You may grow a workhorse. You may grow a unicorn. And that is the beauty of it.
Below is a simple, reliable guide to help you successfully start dahlias from seed, whether you’re brand new to growing or adding seedlings to expand your patch.
Why Grow Dahlias From Seed?
Dahlias from seed offer benefits you can’t get from tubers:
When to Start Seeds
Start your dahlia seeds 6–8 weeks before your last frost date.
For most growers in the U.S., that means:
You can also direct sow after danger of frost has passed, but indoor seed starting gives stronger, more predictable results.
What You’ll Need
How to Start Dahlia Seeds Indoors
1. Fill Your Trays
Use a fine-textured seed-starting mix — light, airy, and moisture-retentive. Avoid heavy potting soil.
2. Sow Your Seeds Shallowly
Place each seed on the surface and gently press it into the soil.
Cover lightly with ⅛" of soil — dahlias need light to germinate.
3. Water Gently
Moisten the soil with a mist or bottom water to avoid displacing seeds.
Keep the soil consistently damp (never soggy).
4. Provide Warmth
Dahlia seeds germinate best at 70–75°F.
With consistent warmth, expect sprouts in 5–10 days.
5. Move Them Into Light
Once sprouted, seedlings need 12–14 hours of bright light daily.
Grow lights placed a few inches above the foliage prevent leggy growth.
6. Pot Up When Needed
When seedlings develop their second set of true leaves, transplant them into 3–4" pots.
This gives the roots space to develop and makes them easier to harden off later.
Hardening Off
About 7–10 days before planting out, begin hardening off:
Never skip this step — it sets them up for strong garden performance.
Planting Dahlias Outdoors
Plant seedlings outside once all danger of frost has passed and soil has warmed.
Spacing:
12–18 inches apart, depending on your style of growing.
Soil:
Rich, well-drained, and amended with compost if available.
Ribier Gardens follows no-till, biologically alive soil practices — dahlias thrive in that kind of living system.
Depth:
Plant them at the same depth they were in their pots.
After a few weeks in the field or garden, seedlings will establish quickly and begin forming small tubers underground — which you can lift and save in the fall.
Watering & Care
Bloom Time & What to Expect
Seed-grown dahlias typically bloom 75–90 days from transplanting — often sooner than tuber-grown plants.
And here’s the best part:
You won’t know what you have until it blooms.
Expect:
That’s the joy and the adventure of growing from seed.
Saving Tubers From Seedlings
At the end of the season, each seed-grown plant will have formed its own tuber clump.
You now have a brand-new variety to grow for years — one you grew yourself from a single seed.
Final Thoughts
Growing dahlias from seed is accessible, rewarding, and full of possibility. Whether you're adding inexpensive volume to your garden or hunting for your own unicorn, these seedlings are where magic happens.
If you’re ready to try, you can find Ribier’s 40-seed and 100-seed packets in the shop — and we can’t wait to see what you discover.