Dahlias are a gardener’s absolute favourite for so many reasons – their great variety, show-flower blooms with rich, sensual colours, a wide range of textures and the fact that they bloom in late summer to keep your garden a magnificent spectacle when most other plants have faded make this remarkable plant a sight to behold.
Dahlias also range in height from about 30cm to over 1 meter, adding much to the structure and depth of planting areas, and making them an ideal as border plants as well as larger backdrops for planted sections.
When to plant Dahlias
Dahlias are not fans of frosty, very cold conditions and are therefore best planted outdoors in early Spring. If you’d like to get an early start though, you can plant the tubers in pots about four weeks before the start of Spring, so around late March or early April.
Place the pots in a sunny position to encourage early sprouting and once the danger of frost has passed you can transplant them gently into their Spring position.
Where to plant Dahlias
Dahlias grow most happily in sunny, well-drained areas as they are firm fans of the sun. Because of their wide variety of heights, colours and densities, you can plant the tubers in a number of locations in your garden to bring the best effect in conjunction with other plants.
How to plant Dahlia Tubers
Dahlia tubers should be planted about 10-15cm deep, and in well-composted and well-drained soil. Prepare the holes well by digging them to a depth of about 20cm and backfilling with suitable compost to encourage early sprouting.
For best visual effect you can plant dahlia tubers between 30-50cm apart depending on variety, and stake taller plants before they get too tall to ensure they don’t droop or fall over.
Keep your Dahlias blooming from June right through until the first Winter frosts by feeding them regularly with high phosphorus fertilisers in a 10-30-20 ratio. You should also protect the plants from pests and disease such as snails and mildew by using suitable sprays.
At the end of the growing season, you can dig your Dahlia tubers up gently and store them for replanting the following Spring. Cut off all but about 15cm of top growth before doing so, and allow them to dry before storing them in a ventilated box or basket filled with slightly moist sand or vermiculite, and in a cool, dry place.
Keep your dahlia tubers moist throughout the Winter and cut away any sign of rot, and replant as soon as the last frosts have come and gone.
Top tips for spectacular Dahlias
- To create bushier plants on the taller varieties, you should pinch off the top growth of the shoots above the third set of leaves while the plants are still young
- Fertilise the plants monthly with a water-soluble product to keep them blooming regularly
- Mulch the ground around the plants to retain moisture and water regularly
- Cut the blooms regularly to encourage ongoing growth and plant density
- Dahlias will also grow in pots and make beautiful features for doorways and more, although potted plants may not grow as big as those planted in open soil.