Tips for growing dahlias
Dahlias haven’t always been in fashion but over recent years, their popularity with gardeners and garden lovers has grown – and quite right too! With their big, bold and colourful blooms, they are a fantastic addition to the garden, especially for a beautiful and bright display in the late summer and early autumn.
At Houghton Lodge Gardens, you will find several varieties of dahlias in the Walled Garden and the Long Border. From bright oranges, and crimson reds to deep purples and pale pinks – from a distance the beds look like a sea of bright pom poms floating on the breeze.
We’ve put our gardening heads together and created some tips for growing dahlias for stunning displays of dahlias in your gardens.
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What do dahlias need?
Dahlias do well in fertile, moist but well-draining soil. They like a sunny, sheltered site.
Taller varieties will need staking and supporting so that the heavy flowers don’t cause them to topple.
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How to get more flowers!
Deadheading – Dahlias just keep on blooming! Make sure to deadhead regularly, this gives the plant energy and space to promote new growth and will extend your plant’s display season.
Don’t just cut off the spent flower, this leaves a long stalk and won’t grow new flowers. Cut back to where the flower stem joins the new stem.
However, there’s a catch! It’s not always easy to tell what is a bud and what is a spent flower. If it is round it is a bud but if it is pointy (conical in shape) then it is a spent flower.
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Pinching out shoots
When the dahlias first start to grow make sure to pinch out the tips of the main shoots to the top pair of leaves. Leave to grow a little more and then remove all shoots but five sprouting from the tuber. This means you’ll get big strong growth and lots of flowers!
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Slug control.
Slugs aren’t a problem right now, (we are in the middle of a drought!), they are in hiding until the rain comes (and who can blame them?) But, when they do rear their slimy heads it is time to water the earth with nematodes!
See last month’s blog for more on nematodes.
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When to cut back.
I started gardening in Autumn and one of the first jobs I did was cutting all the dahlias down.
Once the first frost hits, it’s goodbye flowers. Dahlias have hollow stalks, so it is important to cut them right down because this then stops water from collecting in the stalks and rotting the tubers.
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What about storing over winter?
A question we often get asked is ‘can you leave dahlias in the ground over winter?’
Our Dahlias in the walled garden are very well established and have relatively dry beds, so we do leave ours in the ground over winter. We make sure they all get a good layer of well-rotted farmyard manure to keep them warm and feed the soil.
If your soil is on the wetter side, it is best to dig them up and store them in a cardboard box and a cool/dry place ready to be replanted in the new season.
Want to know more?
I’ve found a great page from Sarah Raven on dahlia care and tips for growing dahlias from seed. Follow this link.
Don’t forget that the gardens close on 30th September so come and visit us before we close for the season.
See you soon,
Cat, Under Gardener
Find Cat on Instagram for more plants and pictures @cat.kin_
