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How to grow dahlias from seed

You will need

  • 10cm pot or seed tray
  • Multipurpose compost
  • Dahlia seeds
  • Plant label and pencil
  • Clear polythene bag and rubber band (for pot) or propagator lid (for seed tray)
Do it: February - mid-April
At its best: late August - early October
Takes just: 20 minutes


Sown now in the greenhouse, dahlia seeds will produce young plants ready to plant outdoors in late May to flower this year. Seed companies sell a range of quick-growing bedding dahlias that are suitable for growing this way. You can also use this method for sowing seeds saved from your own dahlia plants at the end of the previous season.

How to do it


Fill a pot or seed tray with moist seed compost and lightly firm the surface. Gently push your dahlia seeds into the compost. Don't forget to label your seeds. Cover pots with an inflated clear polythene bag, held in place with a rubber band. If sown in seed trays, cover with a propagator lid. 


Seedlings will germinate within a couple of weeks. Once the 'true' leaves have grown, seedlings are ready to transplant into individual pots. Hold plants by their leaves and gently tease them out of the soil. 


Gently transplant seedlings in 10cm pots of multipurpose compost, firm and and water well. In mid-May, harden off plants by standing them outdoors during the day and bringing them in at night. Plant them in their final positions once all risk of frost has passed.

Our tip

Allow a few dahlia flowers to set seed for collection at the end of September. Save them in an envelope over winter to sow in February. You'll get a wonderful mixture of different flower shapes and colours from the resulting plants.

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Talkback: How to grow dahlias from seed
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marghinds 24/11/2011 at 15:27


kaycurtis 24/11/2011 at 15:27

love seeing all the new things from gardeners world, shame some of us haven't got enough room in our gardens to try every thing out, at the moment I am still struggling to get things under control after the winter and my garden is smothered in ground elder as my neighbours think it's ground cover and leave it to romp all over the place. my peonies are comming up nicely though even though they have to put up with heavy clay,

kaycurtis 24/11/2011 at 15:27

enjoy all these little tit bits of information.

jogriff 24/11/2011 at 15:27

In this current financial climate I am having to cut back on heating the greenhouse, am now just keeping it to 'frost-free'. Will this impact on when I can start sowing my annuals, eg. lobelia, and any other perennial variety seeds?

selina 24/11/2011 at 15:27

Hi i don't have a green house can i keep them in the house. I do have covered shelves outside that has been usefull in the summer, is it still to cold to use that?

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