different ways to propagate dahlias, growing from seed, cutting or tubers

DAHLIA PROPAGATION

Dahlias are very popular and beautiful perennial plants that come in a stunning range of colours and shapes, but there can sometimes be confusion about the best way to propagate them, so lets dive into the different ways to grow and propagate dahlias.

DAHLIA TUBERS

The first time you grow dahlias it may be from a single dahlia tuber. These tubers are clones of the parent plants and are dug up in a clump over winter, divided into single tubers by the farmer and sent out as a single tuber in the spring ready for you to plant. As they are grown from a tuber they will be an exact clone of the parent plant, so you know exactly what the flower will look like when it blooms if you buy a named cultivar. You can read more on division on my blog about dividing dahlias (to be published soon, I am adding more photos).

DAHLIA CUTTINGS

Cutting rooted after 12 days on heat table under misters, ready to be potted up.

Roots are now established enough to pot up into bigger pots and give the cutting a chance to put on growth.

You can also take cuttings of dahlias that will also give you an exact clone of the parent plant, cuttings can be taken throughout the season, but for best results, cuttings are usually taken in spring, carefully snip or pull a shoot away from the tuber or clump of tubers, remove the excess foliage leaving the top leaves and place into moist, warm potting mix or other medium and mist regularly, after about 10 to 14 days you cutting should have developed its own root system and you can then pot it up into a bigger pot before planting outside.

Everybody has a different ways of taking cuttings depending on their set up and experience, I myself use a heated tables to keep roots warm (around 22C), in my polytunnels, with misters over head, you may have your own way to keep the cuttings warm, like a small heat mat indoors with lights or possibly if in a warm climate they may need shade cloth to keep them cooler, as you do not want to cook them or them to dry out, you just want them to be warm and moist. I don’t even use a rooting hormone anymore, I find if conditions are correct (not too warm not too cold), they root at the same speed with or without cloning agents like honey or Clonex.

Once they grow roots, then pot them up into large pots with potting mix, remember cuttings grow quickly so make sure you give them enough room to grow their root system and don’t over water the new roots as they can rot, but remember to keep them misted and don’t let them dry out too much, its a delicate balance and may take time to get right.

Once you cuttings are established and big enough so that they wont be eaten by slugs or snails, and in your climate it is passed a risk of frost you can slowly harden off your cuttings and plant out your new plants into their growing position in the garden. they will form tubers if given enough time to grow over the season, if you take very late cuttings in Autumn you may need to keep them safe and warm over winter before they can be planted out the following season

The same cutting 3 days later!

Look how much the roots have grown in just three days after being potted up and been given the space to grow.

If you take cuttings and keep them in pots over winter you will find they make pot tubers, which is really just a mini clump. I find pot tubers to be incredibly vigorous and very productive when they are planted out into the field. They may look small but pot tubers are mighty I love growing them and find them to be easier to grow than just a single tuber.

Each one of these dahlia seedlings is a brand new cultivar

Seed grown dahlias germinate at different time, singles, collarettes and anemones I find germinate the fastest, some even within 24 hours but I have grown seeds in trays that have germinated under the exact same conditions 6 weeks after the first seeds in the same tray germinated. So the trick is to not give up on seeds too fast, keep them warm not hot and misted not soaking wet.

GROWING DAHLIAS FROM SEED

Growing dahlias from seed is probably the funnest way to grow dahlias in my opinion, because every single seed is a surprise and you do not know what it will look like until the bloom.

Dahlias from seed are unpredictable and can vary greatly from the parent plant, but can sometime have similar traits of the parent plant, this is why it is important to grow seed that you know comes from quality dahlias, undesirable traits like bad stems, low petal count or short plants can be passed down through to the seed from the parent plants and you want the best possible outcome out of your dahlia seedling. For this reason it is best to either save seed from quality cut flower dahlias or purchase seed from quality cut flower farms to give you the best chance of quality seedlings. That being said I still get undesirable traits like a bloom with a low petal count from my dahlia seedlings, I simply remove those plants once they flower.

The surprise as each new seedling opens is so much fun, will they be the new big in demand dahlia? Growing from seed is how you produce new dahlia cultivars, the seedlings will not be the same as the parent plant, however they could inherit some qualities of the parent plant like colour or form or could produce an entirely new interesting shape and colour. Dahlias from seed will produce tubers in the first year if grown at the correct time of year, the tuber clumps then either divided into single tubers and you can grow more of them the following season to assess the quality of the plant. New varieties are usually grown for at least 3 seasons to test stability and quality of the blooms and stems etc., before they are named and then released to the public. Dahlia seeds are incredibly labour intensive to save, it is a very long and fiddly process, each seed I sell has been grown, selected, saved, dried, sorted and checked for viability by myself.

Pictured here is just a small selection of the dahlia seedlings I have grown from seed from my own farm.

Each one is an entirely new cultivar that I will grow on and if after a few years I am happy with them, then I will eventually name them with my prefix ‘WILD’ and release them to the public.

In summery If you like a particular cultivar for its colour and shape then buy that named dahlia as a tuber or a cutting, because then you know exactly what it will look like, if however you want to create your own new cultivars then growing from seed is a fun and additive way to grow dahlias. Happy growing Sam.