Tag Archives: Dahlias

Advice for August about Dahlias

How to grow Dahlias

If you want late summer colour choose dahlias. Enjoy different flower forms, from bouncy looking pompons to exotic waterlily styles, and a kaleidoscope of colours to fit every palette.
Dahlias are stalwarts, working hard in borders, pots or as a cut flower crop. Although they flower from June to late October, they are well known for the August / September period. I think they bridge the gap between blowsy summer planting and robust autumn colours. They bring zing to a border so I use a variety of them to introduce a bit of drama in different planting combinations.

Dahlia 'Sunny Boy' showing August colour in the walled garden.

Dahlia ‘Sunny Boy’ showing August colour in the walled garden.

Maintenance is easy. Dahlias enjoy the sun and like a rich, easy draining soil. They have tubers, like potatoes, so feed them well as you will be feeding for next year too. Slugs love them, so you will need to protect them. If you choose tall varieties stake well and early as stems snap easily in the wind.

Consider foliage colour, which varies from light greens to deep purple, giving opportunities to under-plant with exciting combinations. For example, we’ve married orange (pictured) on bright green stems with purples and golds from verbena and heleniums for a blaze of colour.
Grow dahlias from seed, plant tubers or take cuttings in late spring. A packet of seeds will give you dahlias for years.

They die right back at the first frost and you’ll lose them over winter in wet ground or sub-zero temperatures. It’s a good idea to lift them in late autumn after the first frost when the stems flop. You can risk leaving them in the ground with a good mulch to protect them – as long as you are confident of predicting a dry winter that’s not too cold. And if you can do that, come and see me for a job as the garden weather forecaster!

Nick Haworth, Head Gardener