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Best expert advice on growing dahlias

Pink/Purple Pompon Mix from Suttons

You can plant dahlia tubers or grow them from seed, but if you want to know how to grow dazzling dahlias, start with this collection of carefully curated content from the internet. Our comprehensive guide is filled with tips and tricks from those who know dahlias best – experienced garden bloggers and dahlia enthusiasts. Learn the basics from these experts and you’ll soon be growing award-winning dahlias in your own garden or allotment.

Contents

Best advice on growing dahlias from tubers or seed

Dahlia Seeds - Dwarf Cactus Mix from Suttons
To grow dahlias from seed, start with dwarf varieties like this Dahlia ‘Dwarf Cactus Mix’ 
Image: Dahlia Seeds – Dwarf Cactus Mix from Suttons

There’s not much Geoff Hoyle and his wife Heather from Stockport, Cheshire, aka Dahliaholic, don’t know about dahlias as their comprehensive dahlia video growing guide demonstrates. Filmed in their spectacular garden where they raise 150 dahlia varieties from tubers each year, they share their annual routine from March through to November as they turn their entire suburban plot into a dahlia paradise. Quite stunning!

In her excellent beginner’s guide to dahlias, Teabreak Gardener Katharine pots up her dahlia tubers and keeps them in the greenhouse until any danger of frost has gone. Before planting out, she suggests digging some compost and manure into the soil and feeding regularly with chicken manure during the growing season.

It’s best to plant dahlias in rich soil in a sunny spot in the garden according to Carol, The Sunday Gardener, who says that while dahlias will need a bit of time and attention, the results are worth it. Some top advice in her dahlia growing guide is to pinch out the growing tips once the plants are established to get more side shoots and more blooms.

Katy in the Garden has a very helpful, but cautionary, tale about tubers, explaining it’s important to lift and divide dahlia tubers regularly or they could become virtually unmanageable, like the messy example she wryly named “Medusa”. Not all is lost if you have neglected your tubers – follow her simple guide to dividing them for the first time.

Most people cultivate dahlias from tubers, but some varieties can be grown successfully from seed, as Geoff, The Biking Gardener, confirms in his article: Amazing annuals: Dahlias. He recommends limiting your seed growing to dwarf varieties and those with single or semi-double blooms – great for bees and butterflies. His secret is to treat them as annuals and sow in April when the light is good and they’ll germinate quickly.

Best advice on how to overwinter dahlia tubers

Dahlia tubers ‘Orange/Salmon Mix’ from Suttons
Dahlia tubers like this ‘Orange/Salmon Mix’ can be lifted and overwintered at the end of summer
Image: Dahlia tubers ‘Orange/Salmon Mix’ from Suttons

In her beautifully filmed and presented video on potting up dahlia tubers Katrina of Homegrown Garden explains how she lifts her dahlia tubers at the end of the flowering season and puts them in pots of spent compost to sleep over the winter in her basement. Her straightforward step-by-step guide shows you how to get them established again when they wake up in spring, and the results can be seen in a lovely photo of Katrina surrounded by pastel blooms in her dahlia border.

Do you usually dig up your dahlias at the end of the growing season? Alexandra at The Middle-sized Garden says it’s OK to leave dahlia tubers in the ground over winter. She cuts back the old foliage and stems, then protects the plant by covering it well with a big mound of compost or mulch.

Meanwhile Roger Brook, aka the No Dig Gardener, warns that although he happily leaves his dahlia tubers in his sandy soil all year round, they don’t like ground that’s soggy or very cold. And he counters his own claim that overwintered dahlias are healthier and less vulnerable to pests and diseases, by revealing that some of his own plants were invaded by black aphid – a problem he soon sorted, however. 

Best advice on combating dahlia pests

Portable slug and snail trap from Suttons
Lure slugs and snails away from young dahlias with a trap that’s not harmful to other wildlife
Image: Portable slug and snail trap from Suttons

There’s no doubt slugs and snails adore fresh young dahlia shoots and leaves to chomp on. In his guide to getting a great show by growing garden dahlias, Alan from Down to Earth suggests using pellets to control them until your dahlia plants are well established. Earwigs are also partial to nighttime snacking on dahlia petals, but Alan says you can lure them away by popping wood wool into a little flowerpot and perching it on a cane amongst the plants.

Self-confessed dahlia addict Dan, aka The Frustrated Gardener, raises 60 dahlia varieties on his allotment and still wants more! He prefers a natural approach to dahlia pest control and was fortunate to have a frog colony under the shed to gobble up any threatening slugs and snails, as well as a battalion of ladybirds who devoured the invading black flies.

Best advice on supporting dahlia plants

Dahlia ‘Park Princess’ from Suttons
Dahlia ‘Park Princess’ is an excellent choice for large containers if you add a stake for support
Image: Dahlia ‘Park Princess’ from Suttons

Garden designer Jack Wallington, who grows beautiful dahlias organically and peat-free in his garden and allotment in south London, has some excellent tips on how to support your dahlia plants in borders, pots and for cutting. We can’t argue with his philosophy that “when life throws you lockdowns, you’ve got to pick some dahlias.

Over at By Dahlia E, naturopath and wellness blogger Dahlia also happens to grow an abundance of dahlia plants! Her adoration for her namesake flowers is evident throughout her complete beginner’s guide to growing dahlias. She shares myriad tips for novices, including clear instructions on how to stake dahlia plants you’re growing in containers, ready to support the weight of the stunning blooms to come.

Best advice on growing dahlias for cutting… and eating

Dahlia ‘Eveline’ from Suttons
With pink-flushed petals and a dark pink eye, Dahlia ‘Eveline’ looks lovely in a bouquet
Image: Dahlia ‘Eveline’ from Suttons

If you’re growing your dahlias for cutting, you’ll be after good long stems and big, showy blooms. TV gardening expert David Domoney reveals in his concise but informative blog on how to grow dahlias that the way to ensure big flowers is to give all the plant’s energy to the principal bud. Taking off all but three to five flowering stems and any secondary flowering buds should allow the stars of the show to shine.

Interior designer and gardener Rebecca at My English Country Cottage calls them “darling dahlias” for their beauty and variety, and they are one of her top choices for glorious indoor flower displays. She grows her own dahlias for cut flowers and advises you to only pick blooms that are in full flower as buds don’t usually develop once cut from the plant. 

Dahlias aren’t just a pretty face, they are edible too, as Mr Plant Geek explains. Michael’s entertaining blog post, Let them eat dahlias, offers some fascinating evidence of French queen Marie Antoinette’s love for the early varieties brought to France from Mexico. He also recommends dahlia blooms as the ultimate decorative flower for a wedding cake.

Kirsty at Get Planting, who reminds us to water dahlias regularly in hot weather, is also an advocate for eating dahlia flowers, adding petals to salads or using blooms as pudding decorations.

Best dahlia varieties to grow

Dahlia ‘Café au Lait’ from Suttons
Dahlia ‘Café au Lait’ is a firm favourite amongst experienced dahlia growers
Image: Dahlia ‘Café au Lait’ from Suttons

Alexandra of The Middle-sized Garden interviewed dahlia expert and award winning gardener Steven Edney to produce her inspiring and thorough guide to choosing and growing dahlias. When pondering the best dahlias to grow, Steven says to consider whether you want to attract pollinators or produce striking cut flowers. Bees and other insects find simpler single or semi-double dahlias much easier to access for pollen, but the dense and showy pom-pom, cactus or dinner plate varieties look fabulous in a vase. Or you could simply select the dahlias you love the look of.

Sometimes a particular dahlia flower will capture your heart. For Bryony, of Bryony’s Allotment Garden, her favourite bloom is Café au Lait, an exquisite, dreamy, cream-coloured dinner plate of a flower. She actually grows a wide variety of dahlias and declares herself to be a proud member of the Instagram #dahliabrigade. Her joy shines through her words as she describes a freshly-picked bunch of dahlias as the “jewels of my garden” – and we can’t argue with that!     

Café au Lait gets another vote from Naomi, gardening journalist and author of Dahlias, beautiful varieties for home and garden (Pavilion, 2018). Sharing a gorgeous photo of a late September bloom, she describes this dahlia variety as “laggardly but charming, soft, ruffled.

For an abundance of strikingly rich red flowers and contrasting dark foliage try the anemone type dahlia Bishop of Llandaff, as recommended by tropical plant fans Mark and Gaz at Alternative Eden. It’s suitable for containers too.

The 3 Growbags – sisters Laura, Elaine and Caroline – have strong and differing views about the kind of dahlias they appreciate, as they reveal in their honest and entertaining blog post Dahlias: too dire to dare? While Laura eschews elaborate and showy dahlia blooms to opt for quieter and more subtle single varieties, Elaine’s dahlia growing attempts were thwarted by pests. Caroline, meanwhile, is a huge dahlia fan and the more brilliant and daring the better: “In December I get out the Christmas lights and in May I get out the dahlias.

Follow the wise words of the experts and you’ll have a stunning display of dazzling dahlias this summer – in the border, the allotment or even in a container on the patio. And if you’re a bit late to start from tubers or seeds, choosing a potted dahlia plant  will give you the quick results you’re after. Who could possibly resist?

Lead image: Pink/Purple Pompom Mix

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