Dahlias are much-loved blooms that burst into colour in summer and autumn. They are perfect for pots and garden beds and make beautiful cut flowers for the home. If you love filling your garden with colourful blooms, then learn how to grow dahlias from seed and enjoy a rich display of bright blooms all summer.
Dahlias were first discovered in Mexico in the 1600s and were named after the Swedish botanist, Anders Dahl. The first tubers were sent to Europe by Spanish settlers in Mexico. Since then, horticulturists have grown over 30 species and 20,000 cultivars of dahlias that produce various shaped blooms from fun pom poms and balls to species with the same characteristics as daisies, cacti and waterlilies.
How to grow dahlias from seed
It’s best to sow dahlia seeds in spring after the danger of frost has passed. In tropical or subtropical areas, you can start in late winter. Dahlia’s love the sun and grow best in rich, moist and well-drained soil, so pick a spot that receives sun for most of the day, and before sowing your dahlia seeds, enrich the soil with rich compost. If you have clay-like soil, it’s best to grow dahlias in raised garden beds or pots.
When sowing dahlia seeds, sprinkle them over the top of the soil and then lightly cover with additional soil. Gently water the seeds and continue to water them lightly ensuring the soil is always damp but not soaking wet. The seeds should germinate within 7 to 10 days.
Once seedlings are established, fertilise them with a low nitrogen fertiliser. Continue to fertilise them every 3 to 4 weeks and deep water them 3-4 times per week for approximately 60 minutes by sprinkler to ensure the water reaches its deep roots. Blooms will appear approximately 90 days after planting. If your dahlias aren’t producing blooms, they probably require more fertiliser and water. To strengthen dahlia stems for cutting flowers, pinch or cut the centre shoot to promote shorter, bushier growth with longer stems.
Seeds germinate: 7 to 10 days
Soil type: Well-drained soil
Sunlight: Full sun
Flowers emerge: 90 days after planting
Want to grow dahlias in your garden or send someone a Gift of Seeds? Shop dahlia seeds here.