Growing Dahlias From Seed

Growing Dahlias From Seed

Most people will grow dahlias from tubers, but did you know that you can save a lot of money by growing them from seed? let me sh

Growing Dahlias From Seed

Growing dahlias from seed is a much cheaper way to grow stunning dahlias. If you struggle with slugs on emerging dahlia tubers then growing them from seed is a great alternative.

If you want to start building up a Dahlia collection then grow them from seed, you will save lots of money by not buying a load of tubers! You will also gain a lot of experience in growing dahlias without risking an expensive tuber.

There is a good reason that Dahlias are not normally grown from seed however, this is that they don’t grow true to seed. What this means is that a Dahlia grown from seed won’t be the same as the plant the seed came of.

Because of this, it is more of a lucky dip when growing dahlias from seed and why the seed packet will often be sold as mixed, with many different possible colours.

If you want an exact Dahlia, say a cafe au lait, then you will need to get a tuber. These specialist dahlias are grown from cuttings and are a clone of the parent plant.

Dahlia Cafe Au Lait
Dahlia Cafe Au Lait

How To Grow Dahlias From Seed

Use a root trainer if you have one or a module tray if not. In the pictures, you will notice that I multi-sowed my dahlias. I don’t recommend doing this and would instead say to single sow them.

This is because they germinated really well and being multi-sown meant I needed to split a lot of seedlings which I wouldn’t have had to do if I had sown them one seed per module.

When To Plant Dahlia Seeds

Dahlia seeds should be planted from February through to April but the earlier the better.

One thing to mention here is that if you want to get the most out of your dahlias, especially in their first year, then the earlier you can sow them the better. This means you will need some indoor space to get them started early, whether that be a greenhouse, polytunnel or sunny windowsill.

You want to sow dahlia seeds in February or March if possible, this means you will be keeping them inside for quite a while as they won’t be planted out until May, so make sure you have room.


Once you have some seedlings with true leaves, the second larger set that develops, then they can be planted out into larger pots.

If starting your dahlias in early spring then this is something that you will have to do. it will be too early to plant them out into the garden, but way too long for them to be left in a seed tray.

When To Plant Out Dahlia Seedlings

Plant your young Dahlias into the garden or into a pot once the risk of frost has passed, usually around May.

Dahlia Seedlings In A Root Trainer
Dahlia Seedlings In A Root Trainer

The main threat to dahlia seedlings will be slugs, we all know slugs love dahlias and a seedling can easily be completely destroyed overnight.

One of the best ways you can protect your dahlias is by simply growing them on in a protected spot until they are larger plants. Plant collars are also a really good idea and can keep the slugs off.

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08/08/2022 10:32 am GMT
Those Same Dahlia Seedlings Now
Those Same Dahlia Seedlings Now (July)

Above we can see my Dahlias grown from seed now established in the garden. This photo was taken in the middle of July.

Notice how there is still no sign of flowers, this is because these were late sowing, sown in May. They are going to flower in the late summer or autumn.

This is why I advise you to start your dahlia seedlings as early as possible so that you can enjoy them for longer over the summer.

Do Dahlias Grown From Seed Develop Tubers?

Yes, they do develop tubers. They will be a little small at first but will grow into much larger tubers after a couple of years.

You can lift and store them just as you would with bought tubers, or try and leave them in the ground if you are a bit of a risk taker!