Saving the National Dahlia Collection

The National Dahlia Collection has a new home and a new custodian. I’ve been to find out more.

Now I’m a bit of a dahlia addict – my single tuber has somehow increased to around 30 varieties over the past four years – but it requires a certain kind of addiction to take on a collection of thousands of plants.

“I’m absolutely besotted with dahlias,” admits Louise Danks as she tries to explain what led her to rescue the National Dahlia Collection.

It had been near Penzance but a switch in the business that owned the site meant that last year it was looking for a new home. (You can read about my visit to the previous site here.)

“I thought somebody should do something and then I thought I should do something,” says Louise, who had worked with the collection for many years, including taking it to the Chelsea Flower Show.

That ‘something’ involved moving 5,000 crates of mother stock and dahlias over the winter and then planting the tubers this year at a site near Cambourne, also in Cornwall.

The new home is at the Kehelland Trust, a charity that runs a horticultural centre for adults with learning and physical disabilities.

“It just felt like an amazing fit, and the guys at Kehelland are just as dahlia mad as I am so it’s amazing.”

Such is the popularity of the collection, Louise had what she describes as ‘a small army of volunteers’ to help move the dahlias, plant them and keep up with the deadheading.

“The collection is so loved and that was part of the driver of saving it,” she says. “There were lots and lots of people that were desperate to find out what was happening to it.”

Even so, with the dahlias in crates in a polytunnel while she searched for a new home for them, the task did seem overwhelming: “Everyone kept saying ‘What you are you going to do when they start growing?’ and I’d just burst into tears. I just felt so strongly that we had to save it, all kind of reason and planning kind of went out of the window.”

Walking around the field filled with blooms of every shape, colour and size, it seems the stress was well worth it. Already both the species and cultivars have been awarded National Collection status and there were lots of visitors, helping with the deadheading or just enjoying the spectacle.

Louise, who teaches horticulture at the nearby Duchy College, has 1,700 different cultivars and 22 species dahlias and the range is enormous from huge dinner plate flowers to dainty single blooms.

D. merckii has delicate foliage and mauve flowers that would suit a cottage garden style planting. In contrast, D. ‘Happy Single Flame’ is ideal for a border of fiery tones.

Louise isn’t planning to lift the dahlias but will give them a thick layer of mulch and leave them in the ground, possible because the sandy soil is well-drained and Cornwall has mild winters.

If you do need to lift tubers, she advises labelling them clearly and storing them somewhere frost-free and dry in something like loose, dry compost. It’s important to check them regularly to ensure they’re not dessicating or rotting.

She grows her own dahlias in pots – “I’ve got lots of little low Cornish walls so with slugs I don’t stand a chance with any in the ground.” Come winter, she just leaves the dahlias in the containers and moves the whole thing into a shed.

The National Collection’s stock plants are grown in trays and these are treated with nematodes in spring to combat slugs.

Once the dahlias start growing, the advice is simple: “Deadhead, like crazy, and water and feed when they’re in active growth. They’re really hungry and really thirsty.”

Knowing what is a spent flower and what’s a bud is easy – buds are button-shaped and dead heads are pointed. Louise cuts back to a leaf and will keep deadheading until later this month when she will allow seedheads to develop – there’s a bed of seedlings that are being grown on in case they produce something special.

At the moment, the collection is open twice a week and isn’t selling plants or tubers, something Louise plans to start in the future, concentrating on the unusual dahlias.

“There are plants in this collection that nobody else grows. We’ve got some really old varieties in here that you can’t buy in wholesale from Holland.”

And for anyone who says they don’t like dahlias, she has one simple message: “They just haven’t seen enough of them.”

The National Dahlia Collection is open on Wednesdays from 5-7.30 and from 10-4 on Saturdays. More information here.

Top picture: Dahlia ‘Frank Hornsea’

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