Growing Dahlias from Seed

Growing Dahlias from Seed

Growing dahlias from seed can feel a little mysterious. Most people are familiar with growing dahlias from tubers, but seed-grown dahlias offer a different and surprisingly joyful experience.

This year was my very first experience growing dahlias from seed, and the excitement and anticipation of waiting for them to sprout, and eventually flower, has been unforgettable. It’s been such a rewarding experience that I can safely say I’m well and truly hooked. I’m already planning which of my existing dahlias I’ll collect seed from this season, ready for winter when the next round goes into the ground.

Seed growing has its place, especially for gardeners who enjoy experimentation, patience, and the delight of surprise. This blog will walk you through what growing dahlias from seed really involves, when it makes sense, and how to approach it with realistic expectations. 

First, an Important Thing to Know

Dahlias grown from seed will not be true to type.

This means:

  • You won’t get an exact copy of the parent plant
  • Flower colour, size, and form will vary
  • Every seed-grown dahlia is genetically unique

This is not a downside; it’s simply the nature of dahlias. In fact, this is how new varieties are discovered. If you enjoy the idea of growing something completely one-of-a-kind, dahlias from seed can be very rewarding.

If your goal is to grow a specific named variety, tubers are the way to go. Seed growing is about curiosity rather than certainty.

Why Grow Dahlias from Seed?

There are a few good reasons why you should try growing from seed:

  • You enjoy experimentation and surprise
  • You want to grow a lot of plants affordably
  • You’re curious about breeding and variation
  • You don’t mind what the flowers look like only that they bloom

Seed grown dahlias are especially lovely in:

  • Cottage-style gardens
  • Cutting gardens
  • Mass plantings where variation adds charm

Where to Source Dahlia Seeds

If you are already growing Dahlias, then you have your very own source of seeds. If not, then there are quite a few Dahlia farmers in Australia who offer seeds for sale including us. Below are some other farms who offer seeds

When to Sow Dahlia Seeds (Australia)

Dahlias are frost tender, so timing matters.

In most parts of Australia:

  • Sow seeds in late winter to early spring
  • Start them indoors or in a protected space
  • Transplant after the risk of frost has passed

The aim is to give plants a good head start, so they have time to grow and flower before the heat of summer.

How to Sow Dahlia Seeds

What you’ll need:

  • Dahlia seeds
  • Seed-raising mix
  • Small pots or seed trays
  • Gentle watering can or spray bottle
  • Plant labels (this is if you want to keep track of each seedling)

Step-by-step:

  1. Fill trays or pots with seed-raising mix
  2. Sow seeds on the surface and lightly cover (about 5 mm)
  3. Water gently so seeds aren’t displaced
  4. Place in a warm, bright position (out of direct harsh sun)
  5. Keep soil lightly moist, not wet

Seeds usually germinate within 7–14 days.

Dahlia seeds after 14 days

Caring for Seedlings

Step-by-step:

Once seedlings appear:

  • Provide plenty of light to prevent plant growing long and lanky
  • Water when the surface dries slightly
  • Avoid overfeeding early on

When plants have 2 to 4 true leaves, they can be:

  • Potted up individually, or
  • Hardened off gradually before planting out

Take your time with this stage. Strong early growth sets plants up for the season. 

Seedlings potted up individually

Planting Out

For me, I take one more step before planting them in the garden. Unfortunately, we share our farm with a healthy community of Bandicoots, Wallabies, Bush Turkeys and Hares all of wish love to either eat or dig up Dahlias. I pot them up into bigger pots once they have 4 good leaves and leave them in the pots until they are about 20cm tall. Planting them out then gives them a better chance of survival against the critters.

When planting out your seedlings choose a position with:

  • Full sun (at least 6 hours)
  • Well-drained soil
  • Protection from strong winds if possible

Space plants well. Seed-grown dahlias can still grow quite large, and good airflow helps prevent disease. I generally plant my seedlings in the breeding patch 300mm apart as I want to be able to fit as many in as I can. If you are planting them in the garden for a display anything from 400mm to 600mm will give them plenty of space

Flowering: Expect Variation

This is where seed grown dahlias become exciting.

You may see:

  • Single flowers
  • Semi-double forms
  • Unexpected colours
  • Some plants better than others

Some may be ordinary. A few may be beautiful. Occasionally, one will stop you in your tracks.

That unpredictability is part of the charm.

Below are a couple of first year seedlings grown on our farm in 2025/26

   

Can You Save Tubers from Seed-Grown Dahlias?

Yes, and this is often the most rewarding part.

At the end of the season:

  • Lift tubers as you would any dahlia
  • Store them carefully over winter
  • Replant the following season

If you loved a particular plant, saving its tuber allows you to grow that exact dahlia again.

A Gentle Word of Encouragement

Growing dahlias from seed isn’t about perfection. It’s about curiosity, patience, and being open to what the garden gives you.

Some years the results will be modest. Other years, you may discover something unexpectedly special.

If you enjoy learning by doing, dahlias from seed are well worth a place in your garden.

If you’d prefer certainty, named varieties, or want to skip straight to reliable blooms, tuber-grown dahlias are a wonderful option. But if you enjoy the journey as much as the outcome, seed growing has its own quiet magic.

Maleny Dahlias

 

 

 


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