From the border to the vase: Fascinating Dahlias

By Veronica 

Mexico’s national flower has made its way into our gardens and has become a must-have.

It is so versatile with so many shapes and colours available, it simply suits every garden style, adding late summer colour.

Plant some bold-coloured ones, in red or pinks for the japanese garden. They will replace beautifully azaleas and rhododendrons for the late season. Try the most exquisite fringed flowers or dark –leaved ones in an exotic scheme; they are real natural curiosities. Or pack the beds with pastel shades, ideal for a romantic soul in a cottage-like setting.

Either way, you’ll find these beauties very rewarding and floriferous once you follow some simple steps to make the most of them.

When to plant:

From March, plant the tubers in pots or trays with the cut old stem upwards. This is the best time to get unusual varieties at the best price. Make sure the tubers (the roots) are still fleshy rather than wrinkled for best results.

Use good, free-draining, compost. You will need to keep them moist but not wet so avoid heavy clay. In May, when the risk of frost has passed, plant them out. Again, if your soil is heavy, mix in some grit for added drainage.

In the summer, potted ones are available. Although, you won’t have access to the same range, if you are a beginner gardener or you lack of space, it is an easy way to start and get instant colour.

When planting in their final position, allow enough space for them to grow (60cm is good or a pot of at least 40cm in diameter).

Growing Requirements

As explained, Dahlias need well-drained compost and a spot in full, sheltered from cold winds. After all, they are central-american native plants.

Feed every 2 weeks with a fertilizer rich in potash such as Tomato food as this will promote flowering.

Dead-heading (if you don’t use most of the flowers for floral arrangements!) is an important part of the maintenance. As for seasonal bedding, it prolongs flowering. Use sharp scissors or secateurs and cut the whole flowering stem rather than right under the spent flower.

Overwintering your dahlias

The best practice to keep your Dahlias from one year to another is to lift the tubers once the first frost as cut them back (the foliage goes black). Cut the foliage about 10cm above the ground and lift the tubers with a digging fork. Remove as much soil as possible around the roots and place these in a frost free and dry place for the cold season.

You may try to leave the tubers in the ground for the winter if you live by the cost and the risk of frost is minimal. In that case, cover the area with straw. If the soil gets too wet, the tuber will rot. Be aware also of nocturnal visitors, dahlia tubers are edible and mice often go at it!

Planting Combinations:

Cottage Garden Style: Gypsophylla (baby’s breath), Lychnis (Ragged-robin) and ornamental grasses. The contrast between the large-flowered dahlias and the airy smaller flowers works beautifully and guarantees a good supply for gorgeous bouquets.

Lychnis ‘Petit Henri’ ©Windyridge Garden Centre

Exotic: Canna Lilies for vibrant colours with the flowers as well as the foliage.


Canna ‘Cannova’ ©Windyridge Garden Centre

Prairie Style: Grow the single flowered varieties with the tall Verbena for a pollinator-friendly option.

Verbena ‘Santos ©Windyridge Garden Centre

To conclude, even though these are not fully hardy and need a little bit of care, these extravagant beauties are real show-stoppers and will turn any garden or balcony into a colour paradise from July to October.

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