Clumber Gardener: Dahlias bring great colour to your garden

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The dahlias in the herbaceous, Long Range and cut flower borders in Clumber’s Walled Kitchen Garden are at their best in August.

We’re growing around 30 varieties, ranging from established favourites like ‘Bishop of Llandaff’ to modern introductions.

They enjoy the sun and shelter of the garden and we combine them with late flowering perennials, such as sunflowers and crocosmias, and plant them where the early flowering tulips and wallflowers have been removed after they’ve flowered.

Dahlias with decorative foliage are in vogue at the moment, and rightly so. I’ve sung the praises of the ‘Bishop’ series of dahlias in these pages before.

They have dark leaves and come in a variety of colours. Varieties with deep bronze and purple foliage look good even when they aren’t flowering.

We’re growing ‘Star Wars’ for the first time (worth growing for the name alone). Its leaves are a dark bronze, not quite as dark as Darth Vader’s cloak, and the blooms are bright orange and yellow.

Plants grow about 30cm/12ins tall, so it is a good one for the front of the border. Regular dark leaved favourites in our borders are ‘David Howard’ (orange flowers) and ‘Fire Mountain’ (red flowers).

Newcomers are the orange flowered ‘Moon Fire’ and the pale pink ‘Twynings After Eight’.

You can buy dahlias in spring and in summer. Rooted cuttings can be bought mail order from a dahlia specialist in early spring.

This will give you the widest choice of varieties, but you will need a greenhouse to pot up plants and grow them on before you plant them out in the garden.

The other option is to buy tubers from garden centres. These can either be potted up and grown on under glass, as with the rooted cuttings, or planted in the place they are to grow in early to mid May.

Any growth emerging above ground will be tender and could be damaged by frost, so it will need protecting against late frosts.

The easiest method is to buy container grown plants from a garden centre in early summer.

The only disadvantage to this is that plants will need regular watering if the weather remains hot and dry through the summer.

Taller growing varieties may need supporting and faded flowers should be removed to encourage a succession of new blooms.

In addition to making great garden plants, dahlias are good as cut flowers. A star this summer has been the mauve and white flowered ‘Tommo‘.

We try to cut blooms first thing in the morning, before the sun has become too fierce and put them in water in a cool dark place straight away. This helps prolong their display life.

This summer we are experimenting by leaving our pot grown dahlias in their pots and planting directly into the soil. The idea is that this restriction will cause the plants to form firm plump tubers which will store better over the winter. We will keep you updated on how well it works.