How to grow dahlias from seed

Do it:

Feb, Mar, Apr

Takes just:

20 minutes

At its best:

Sep, Oct, Nov

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.

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)


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.


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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