How to Grow Dahlia from Seeds

Have you spotted the flamboyant dahlia flowers and thought to yourself, “I’ve got to get these”?

Well, dahlia seeds are not that difficult to come by. You can get yours for planting from your local nursery or even pick from your collection.

Producing dahlias from seed will save you a whole lot of bucks compared to buying tubers. This is because you’d have to buy like 10+ tubers just to get a small nursery going.

On the sunny side, dahlia flowers give quite a bright array of color, size, and form. They are also easy to grow and reproduce.

Though when dealing with seeds, you’ll have to practice a bit more patience. This is because dahlia seeds may need a few seasons before they bloom.

So, what more is there when learning how to plant dahlia seeds? Let’s find out.

What are dahlias?

Dahlia flowers are a type of annual flower that boasts both ambiance and variety. Scientifically, they are also known as Dahlia variabilis.

Today, I am going to show you how to grow your dahlias from seed.

Growing dahlias from seeds can prove fun and enlightening if you have enough patience. Traditionally, however, dahlia flowers get reproduced through tubers.

Worth noting is that a lot of dahlia flowers are popularly grown for show purposes.

Show varieties normally get raised from tuber cuttings as opposed to planting seeds. This is because show gardeners argue that dahlias raised from seeds don’t reach show standards.

You can easily find dahlias to plant from seed catalogs and nurseries.


Originally, the dahlia comes from Colombia, Mexico, and Guatemala. In these respective countries, you can find them growing in the high plain regions.

The high plains have well-drained soils that receive rainfall for the better part of the year. This way, the dahlias get enough moisture to ensure successful, vibrant, and natural growth.

Well, it was first thought that the dahlias were sub-tropical plants. Recent observations however have shown that they can also grow in very cool conditions.

Early cultivation of dahlias started with the early settlers after getting discovered in the 16th century by British botanists. They started by first introducing three hybrid species from Mexico.

The Coltness Gem was the first successfully bedded dahlia way back in 1922. And up to this day, you can still find a blend of colors existing under the same name.


Dahlia flowers come in numerous varieties. All these varieties also come with their unique petal and color design.

And if you spend enough time around them, you’ll observe that different species have different sizes. Although, the big size and life radiating from their attractive flowers remain constant in all of them.

But, enough about all that…

Let us see how the dahlia holds up in the profile summary I prepared below:

  • Light requirement:   Full sun
  • Total germination days:     3 to 5 days
  • Germination temperatures: 65 – 70 degrees Fahrenheit
  • Expected plant height:   40 to 60 inches
  • Required planting space: 9 to 12 inches apart
  • Harvest:       Just before the blooms completely open

How do dahlia seeds look like?

Dahlia seeds develop inside a seed pod.

Once the pods become ripe, they later dry out and you can find seeds inside if you open them.

Generally, dahlia seeds come with a thin, long physical appearance. For approximation, they can measure up to ½ inches in length. They also have predominantly black color for all the dahlia variety.

Most of the time, many home gardeners don’t store and collect dahlia seeds from their gardens. This is because tubers give a more consistent result when propagated.

Growing dahlias from seeds vs tubers

Planting Dahlia tubers is a much faster and more dependable method of growing. Planting seeds, on the other hand, takes quite longer but offers a great way to extend your dahlia crop.

Nevertheless, growing dahlia seeds is not difficult. If you follow the set guidelines, you will still find success and a band of colorful blooms.

Worth noting again is that dahlia tubers, like most bulbs, contain the crops’ DNA and organic information. That is why propagation from tuber cuttings results in a duplicate copy of the parent plant.

On the contrary, propagation from seeds most of the time results in a slightly altered variation of the parent plant. That is why show breeders and collectors don’t fancy starting their crop from dahlia seeds. – Usually, it is just one big uncertain gamble.

As a result, you might too find yourself collecting tubers from your favorite breeds to replant in the following years. This is oblivious to the fact that dahlias plants produce a ton of seeds when it’s time for harvesting.

Tip: It may serve your best interest to keep some of the dahlia seeds that you’ll harvest. In some instances, these seeds may give rise to a more superior breed than the parent crop. Wouldn’t that be just super?

When should you plant your dahlia seeds?

After you have decided to go with the seeds, I’d advise that you first start growing indoors. This should all happen about 6 to 8 weeks before your area’s last frost date.

If you don’t know your region’s last frost dates, you can quickly look it up in the US Hardiness Zone Finder.

Planting after a frost provides the right environment for your dahlia seeds to grow. It will also give them enough time to get ready for transplanting to other exterior spaces.

In addition, it will also give them ample time to bloom just as the summer months kick in.

I should mention too that it will take between 100 to 200 days for your dahlia seeds to start producing flowers.

How to grow dahlia from seeds

I am now going to show you how to grow dahlia flowers from seeds. I am also going to highlight a few diverse methods that you can use. Just pick whatever gets your groove.

Now, when planting at home, dahlias seeds require relatively high temperatures during germination. You should then follow this with frost protection up until it is time to do transplanting.

Not to burst your bubble – but you may spend a whole season before you spot flowers from seeded dahlias.

In addition, the first year of growth will result in slender tubers that are not worth harvesting. After this first growth, it may take the seeded dahlia another 1 or 2 years before they develop healthy production nodes.


1. Collecting seeds

You have to start by first harvesting ripe seed pods. These pods contain a lot of dahlia seeds.

To harvest, wait until when the pods turn light green and the plant has dropped all the ray petals.

The seeds at this time will have a black, gray, or dark brown color.

2. Preparing the seeds

First off, you have to let the seed pods dry off before extracting the seeds. After removal, also allow the seeds to dry before storing them.

When early spring comes, plant the dahlia seeds in a starting mixture (soilless, mind you) in flats.

3. Soil and spacing

During planting, you have to space your seeds 1 inch apart. Then, make a light covering of the seeds using the same soilless mixture.

Afterward, add moisture to the mixture then move the flats over to a warmer location. The ideal temperature should be, at least, 70 degrees Fahrenheit.

If the plant gets this, the seeds will germinate after 7 – 12 days from the day of sowing.

4. Potting and transplanting

Potting should only happen after the dahlia seedlings have grown big enough that their leaves touch.

Ensure that you plant the seedlings individually in containers that are at least 3 inches wide.

After hardening, you must make sure that your area has passed all the dangers of frost before transplanting.

On the other hand, you may also plant your seedlings outside one week before the last frost date. That is an alternative method of hardening.

However, take notice that this method may make your dahlias fail to bloom in time if you live in the northern climates. In the cold temperatures after the summer, move your dahlias indoors or inside a greenhouse to avoid weather damage.

Tip: You have to harden the seedlings first before transplanting them outdoors. To harden your dahlia seedlings, take them outside during the days to receive the natural sun. Then when night comes, return them inside the house.

5. Growth

As I hinted above, your dahlia crops won’t develop a worthwhile tuber in their first year of growth.

All in all…

To conserve dahlia tubers, you must take them indoors and leave them to go dormant. This will protect the plants’ tubers and root systems from getting damaged by the extreme cold temperatures.

When the next planting season comes, again ensure that you’ve hardened them before replanting outdoors.

Doing this will give you big, elegant dahlia plants with many alluring flowers.

It is from the flowers that you’ll get dahlia seeds that you may use in the subsequent growing season.

Other methods for planting dahlia seeds

Apart from the above procedure, you can also use the following methods to germinate dahlia seeds.

1. Using paper towels

To do this:

  1. Take a piece of wet paper towel and place a flat of dahlia seeds on it. Afterward, cover the same seeds using another paper towel.
  2. Insert the paper towels with the seeds inside a zip lock bag.
  3. Place the zip lock on top of your fridge and leave for 3 to 5 days. The refrigerator provides warmth for the seeds’ germination.
  4. After you notice germination, you can then plant the young seedlings in a tray.
  5. Afterward, put the tray beneath a grow light to provide consistent light and warmth.

2. Using seed trays

To do this:

  1. Feel your seed trays using a soilless mixture (the seed-starting kind).
  2. Poke tiny holes in every single seed cell and plant one dahlia seed in each one of them.
  3. Thoroughly water the tray and use an acrylic dome (clear) to cover it.
  4. You can then place your tray under a grow light or on top of a heat mat. Doing this also provides the seeds with enough warmth for proper germination.

Producing tubers from dahlia seeds

Your dahlia crops will produce tubers at the end of every successful season. The only setback, as mentioned earlier, is that first growth tubers may not be as desirable.

Simply put, often they are not worth the trouble of storing or collecting.

But when your dahlias start producing viable tubers, it will be nothing short of smiles all the way. Part of the reason is that dahlia tubers give rise to crops identical to the parents as I had said earlier.

Come to think of it…

You might want to sort through your seeded dahlia plants also to see which varieties you may want to keep. This way, you’ll have another avenue of getting new breeds that you can name and add to your dahlia collection.

Other varieties available

Well, dahlia varieties come in different heights ranging between 10 to 24 inches. They also come with single or double flowers. What’s more, did you know that some varieties even have collaret flowers!?

Take the Coltness Mixture for example. It grows up to heights of 24 inches and has a clear, radiant, single flower growth that comes in diverse colors.

The Sunburst is another alternative with similar characteristics to the Coltness Mixture. It also reaches heights of 24 inches. The only distinguishable trait over the Coltness Mixture is that it has bigger flowers. In addition, it also has a much wider range of brilliant, light-toned colors.

Finally, the last variety that I’d like to highlight is the Mignon. This dahlia breed only grows to a total height of 12 inches (a dwarf compared to the other two mentioned). The Mignon produces a single flower mixture that comes in many colors. It may start blooming at a height of about 6 inches and also delivers very attractive flowers in the end.


Growing dahlia seeds does not require a lot of brawns. It is always more of a waiting game with this charming, multi-faced flower.

Provided you plant the seeds in a well-drained mixture, you will have nothing to worry about.  Just ensure that they receive enough light and warmth and you’ll have healthy germination.

Worth remembering is that you will have to wait for almost 2 seasons to get viable tubers for propagation. But still, do not forget the chance that you may have getting new, better breeds from seed planting.

I hope this information has helped you learn how to plant dahlia seeds. So, do you now feel like you’re up for the challenge?

Try your hand and let me know your experiences in the Comments Section below!


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