A Guide to Growing Dahlias

Sowing Dahlia Seeds

Dahlia seeds can be sown from early to mid-spring and can be planted out after the last frost. To be exact, the best month to plant dahlia seeds is April to achieve colourful blooms in time for summer. Follow these steps below to achieve successful seed germination.

1. 1. Fill a modular tray or pot with compost until around 1cm of space is left at the top.
2. 2. Place seeds into the compost.
3. 3. Sprinkle a thin layer of compost over the seeds.
4. 4. Water through and place in a warm dry place to germinate.

Growing Dahlias from Tubers

Growing Dahlias from tubers is a less time-consuming process and produces blooms quicker. You can buy tubers from garden centres and shops or even save your own if you have previously grown dahlias.

Gather a pot for each individual tuber and place tubers onto a layer of compost. Ensure the tuber goes into the pot with the new growth facing upwards. Cover with compost and water in well to encourage new growth. Then place the pots in a frost-free place like a greenhouse or windowsill. Hopefully, by the middle of spring, you will have a large amount of new growth ready for them to be planted out.

If you are planting your tubers out after the last frost or transplanting them from pots, they can be planted directly into the ground. If the plants have been kept indoors, harden them off to ensure they survive outside. You can do this by leaving your plants outside during the day and bringing them indoors at night for around a week, otherwise known as hardening off the plants.

Once hardened off dig a hole into the ground or bed big enough to fit the tubers in, but at the same depth as the pot. Dahlias like having space around them to gather nutrients so ensure to plant them between 50-60cm apart. Water in well so they can adjust to their surroundings.

Dahlia Plant Care

 Many varieties of Dahlia will require support to be built to help hold the flowers in place as the weight of the flower heads can lead to them bending or snapping. Supports can be made using twigs or canes, in a grid-like formation.

To encourage constant blooms, deadhead dahlias when the petals begin to drop or when there are no petals left on the flower. This promotes new growth and consistent blooms throughout summer. You can also pinch dahlia plants to encourage larger amounts of flowers and bushier growth.

Dahlias also make great-cut flowers due to their sturdy stems. If you’re wanting to make some beautiful bouquets dahlias will be a great addition to your garden. Simply cut the stem where it meets the rest of the plant and arrange it to your delight.

How to Save Tubers

 Saving dahlia tubers allows you to store your favourite flowers ready to plant out for the following year.

As the dahlias begin to die off cut the top of the plants off ensuring not to cut the plant too low (around an inch from the surface). Then lift the tubers out of the ground with a fork and place them into a pot or box. Once out of the ground make sure to store the tubers in a cool, dry, and dark place to discourage the plant from producing new growth. Also, make sure that the tubers are kept in a frost-free place to avoid damage.

Problems When Growing Dahlias

 A common issue when growing dahlias from tubers or seeds is slug damage. Young dahlia plants are extremely susceptible to slugs, which can cause the plant to die. To avoid this, you can try natural slug control methods or use a slug repellent such as feed and protect to alter the taste of the plant, so it no longer appeals to slugs.

A problem with older dahlia plants and flowers is aphids, as they feed off the plants taking the nutrients dahlias need to survive. A great way to deter aphids is by encouraging ladybirds into your garden as they feed on them. You can do this by creating bug hotels or purchasing ladybird larvae.

To deter aphids another method is to regularly mist the plant with water, as this discourages them from laying their eggs on the plant.