Growing Dahlias from Seed

You can propagate dahlias in a number of ways from tubers, cuttings or seeds. Seeds are a fun way to propagate dahlias as every flower will be a surprise. Just like tubers and cuttings a dahlia grown from seed will grow to full size and produce flowers and tubers that can be dug and divided at the end of the season.

The best time to start dahlias seeds is in Spring after all chance of frost has passed. For us in Nelson this isn’t until November. If you want to give your seeds a head start you can start them inside six weeks before you want to plant the seedlings in the ground.

It is common for people to pre-sprout the seeds in damp paper towels. Place the seeds on a damp paper towel inside a container (we use the plastic takeaway containers) and place somewhere warm, the top of our hotwater cupboard is the perfect spot for raising seed babies.

Remember to check on your dahlia seeds regularly. Dahlia seeds germinate between two and ten days but can take up to 22 days. When they sprout you will see a little white root growing out of the bottom of the dahlia seed, once this happens they will need light to grow.

Once the dahlia seeds have sprouted move them to a damp tray of high quality seed mix, we use Dalton’s Premium Seed Mix. Make sure the baby root and up to half the seed is covered with mix. At this stage they can go outside in a sheltered spot if there is no chance of frost. Otherwise you could grow them on in a greenhouse or use a plastic container to create a warm, humid environment. Do not put them in full sun or the seedlings will cook.

When the dahlia seedlings grow their first true leaves you can move them from the seedling tray into individual pots. Now is a good time to start hardening them off if you have been growing them inside.

Once the dahlia seedlings get to 7-10 cm tall they will be big enough to plant into the garden. Don’t forget to sprinkle them with slug bait when planting out or the slugs and snails will eat all your hard work.