Claus Dalby on how to create a wonderful display with dahlias in pots
Gardener, photographer and author Claus Dalby has a display of dahlias in pots that look like a glorious herbaceous border.
There must be several hundred pots massed together, with both dahlias and other plants. The display can be switched around when a flower goes ‘over’ or if the colour balance needs a boost.
Claus is famous on Instagram and he has a beautiful Claus Dalby YouTube channel, where he shares tips and inspiration from his garden. He is Danish, although the YouTube channel is in English. It’s about ‘gardening, hygge and Scandinavian lifestyle.’ He’s written 30 books on design and lifestyle in Danish, and his first book in English will be out next year.
The garden is near Aarhus in Denmark, which has a roughly similar climate to the UK and to USDA Zone 8. But, of course, one of the wonderful things about pots is that you can switch plants around or bring them inside easily if you need to. A pot-based garden is ideal if you want to grow plants that may be a little too tender for your climate.
A large garden sub-divided into smaller gardens
Claus’s garden is around an acre, but is divided up into 15 ‘rooms’. Each zone is a small garden in itself. So his ideas work for small, large and middle-sized gardens.
When he first moved in, it was mainly laid to lawn. Now there isn’t an inch of lawn left. There are lots of inspiring elements, such as hornbeam trees pruned ‘umbrella style’. But, above all, it’s Claus’s use of colour and pots that is so exceptional.
So I’ve asked Claus to show us how he creates his container gardens. The full interview and fabulous views of his garden are in this video on YouTube, but I’ve summarised the main points here.
Do dahlias grow well in pots?
They certainly do. Claus grows most of his dahlias in pots and the display is fabulous. He grows a wide range of varieties, sizes and colours.
Dahlia grower Sarah Raven suggests that you should choose the shorter dahlias for pots because they’re less likely to flop. But Claus puts a circular support onto the pot at the time of planting so he is able to grow the bigger dahlias in pots, too.
In fact, most plants will grow in pots, including trees. (See here for general tips on growing plants successfully in pots.)
How to plant dahlias in pots
Claus begins in April, which is early spring in Denmark. He first puts the dahlia tubers into standard plastic pots. The pots are not much bigger than the dahlia tubers, so they fit quite snugly. He then adds just a thin layer of soil on top. ‘I put just 1cm of soil on top of the plants,’ he says. ‘They seem to start to grow quicker.’
He keeps these pots of dahlias in a frost-free greenhouse.
After around 5 weeks, the early foliage of the dahlias has emerged. So he plants them into their permanent containers. Once again, he plants quite snugly. ‘I sometimes put three tubers into a large pot,’ he says. In smaller pots, he’ll just put one tuber.
At this stage, he’ll also fix the support for bigger dahlias into their pots.
Dahlias in pots need regular fertilisers and watering.
What to plant with dahlias in containers
Claus says that plant partnerships are very important. Most of his pots only have one variety of plant in them. But the whole display mixes a wide variety of plants in pots. It is a beautifully balanced riot of colour.
He plants annuals in pots, such as cleomes, as well as shrubs like ninebark and philadelphus. Any plant will grow in a pot, at least for a few years.
Repeat the varieties of plant in the grouping
Claus believes that repetition is very important when planning either a border or a grouping of pots. You will see the same lilies, begonias and dahlias repeated along the pot grouping.
His next tip for creating a dramatic colour grouping – plant some pots with contrasting lime green or ‘chartreuse’ foliage. It sets off the dark leaves and rich colours of the dahlia flowers. His favourites include Aralia cordata ‘Sun King’, Physocarpus ‘Nugget’ and Philadelphus ‘Aureus’.
The philadelphus and physocarpus can grow quite tall, but Claus cuts them down to 20-25cms in spring. New, bright green foliage springs back. You don’t get the flowers if you cut them back in spring. But Claus likes these plants for their foliage not their flowers.
Another way of adding that splash of citrus bright is to include a flower like orange begonias to the group.
Add height to the grouping of pots
The next tip is to add contrast with height. ‘Spikes are very important’ in the pot display, explains Claus. Plant some taller, upright plants in your grouping with the dahlias.
Many of the plants in Claus’s pots are ones we normally think of as border plants. For example, he has Cleome Violet Queen, Buddleias Purple, Angelica Gigas and Verbena bonariensis.
He also has lilies, which grow particularly well in pots. Many people keep their lilies in pots and wedge them into the border in time for a beautiful display, then whisk them out when they are over.
Contrast flower sizes
If you have large flower heads, such as dahlias, in a border or grouping of pots, Claus adds contrasting small flower heads. For example, verbena bonariensis, which is tall and airy, with tiny flower heads. In spring, he cuts the verbena bonariensis plants back to about 10cm, which makes them more bushy and less tall when they flower in summer.
What to do with dahlias in pots over winter
Claus takes all the dahlia tubers out of his pots for the winter. He cleans the soil off and wraps them in newspaper. ‘Then store them somewhere where the temperature doesn’t go below around 5C,’ he says. ‘It’s important that they don’t freeze.’
He re-uses the same tubers the following year, planting them out in plastic pots in early spring.
There’s more advice on looking after dahlias in winter here.
More about dahlias and pots
To find out more about growing dahlias, see our ‘what you need to know about growing dahlias’ post.
And for more ideas and inspiration on grouping pots, see 5 ways to use garden planters, plus potscaping tips. And, of course, because plants like dahlias are dormant in winter, here’s some inspiration on what to put in your pots in winter!
And it’s worth remembering that these evergreen pots look brilliant all year round.
However, all plants in pots need care to look their best. They are completely dependent on you! See this post to find out how to keep your pots looking their best.
Dahlias in pots and borders need regular dead-heading, so I keep a pair of snippers by the back door. I can just pop out when I have a moment and snip off any dead or dying flower heads. The more often you do this, the more flowers you get. So don’t leave dead-heading to a once-a-week-job in the garden.
I use Darlac snips, which were recommended by Frances Moskovits. I wrote about her borders in ‘How to Make a Garden Border Look Amazing’, which has been one of the Middlesized Garden’s most popular posts. The Darlac snips are available on the Middlesized Garden Amazon shop (please note that Amazon links are affiliate, see disclosure.)
But if you don’t want to do dead-heading, then find out how evergreen plants work brilliantly in pots to give you year-round interest.
Pin to remember dahlias in pots
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