Growing Dahlias from Seed and overwintering tubers

One of our latest plant obsessions is the Dahlia, since growing them from seed and realising just how easy it is to get many years out of these lovely plants.

Perfect for pollinators, as cut flowers and for bold borders, we absolutely love the diversity of plants that can be grown from seed.

I first attempted these many years ago, with a tray of seed under my living room radiator. It was so successful it led me to grow them every year since and as you collect your own seed at the end of each summer, your collecting a huge batch of genetics for the following year!

Several years after saving seed from a bright yellow cactus Dahlia

Favourites can be carefully dug up and the tuberous roots can be divided to create new plants

An essential flower for any gardener who wants to encourage the bees! These flowers are bold and dramatic, attracting so many pollinators to the garden!

Overwintering Dahlia Tubers

We dig up the underground tubers when they finish flowering and bring them into a dry area. If you have space, you can put your tubers into dry sandy soil or sawdust and keep dry and frost free.

A patch of Tubers dug up, if you don’t, the rabbits might do it for you!

You can separate the bigger, mature tubers at this point to create a whole new plant for free!

We put ours into dry gritty soil in the polytunnel and keep them as dry as possible until the hot days arrive in Spring and we begin watering them in early March
March 24th we see new shoots appear
By 1st of April they’ve more or less all come through

We grow more Dahlias from seed every year!

For some comparison, here are some Dahlias we just started from seed in February, looking really strong and healthy, but without the chunky tubers full of nutrient, so they are much more vulnerable

When spring arrives and frost is clear we can put them back outside and enjoy their beautiful flowers for another season.

We left some of our dahlias in the polytunnel to see how they would cope and they grew incredibly quickly, and started flowering in April! I could dedicate a whole polytunnel to growing them…. I love them that much!

Dahlias can flower late into autumn, which makes up for the time waited for them to blossom

Sometimes, tubers left in the ground here, survive the Rabbits and less harsher winters and come back stronger than ever!

Tips and Advice

What we have learnt

Rabbits love Dahlia tubers!!! If you do decide to leave your plants in the ground over winter, you may benefit from covering them with something so they cannot be eaten! We are in a rural area and have a massive rabbit problem!

Tall Plants will benefit from support. Plant supports can be bought online or in garden shops and can be placed around the young plant to grow through and not fall over. You can even make one yourself from foraged branches.

Any soil that drains well. We don’t find these to be particularly fussy in terms of soil and have grown them in good and bad areas of the garden. I’ll often see Dahlia tubers unsold at the garden centre in summer, growing into healthy plants inside the plastic packaging with absolutely no soil or watering! Generally they like a rich soil with good drainage so as not to get waterlogged or they can rot. You can always give them an organic plant feed to give them a boost before flowering! Check out our page homemade fertilisers here.

Grow from seed! There are so many different varieties of Dahlia available to grow from seed and we would recommend it to anyone. We start some seed off early in February, indoors under lights and have really good results. They like to be warm and humid and once they pop through, will grow quite quickly. A simple windowsill propagator will do, or you can wait until the frost passes and grow straight outside.

They perform well in pots too. There are many varieties that grow shorter, strong stems perfect for growing in containers as they don’t need plant supports, and the flower heads aren’t so big they keel over. When it comes to collecting tubers, they are also much more accessible as there is no digging required!

Deadheading is beneficial if you want to encourage more blooms to follow. We cut a lot of our blooms for the vase which saves deadheading duties and brightens up the inside at the same time!

Save your own seed for random natural selections the following years! Once they have finished flowering, cut off flower head and pop it in a paper bag or envelope. Let the seed heads cure for a few weeks or until you want to sow them in Spring. Seeds need to stay cool and dark ideally.

Split your tubers to get more plants for free!

If you’d rather read about growing vegetables, see our page ‘The Edible Garden‘ to have a look inside the old greenhouse that is evolving into a permaculture garden.

Follow us on Instagram for more photos of our journey!

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