Seven common garden-design mistakes, and how to avoid making them

Telegraph

15-02-2025

When Pollyanna Wilkinson made the career switch to garden design eight years ago, she realised there was a lot more to creating a successful garden than simply being greenfingered. 'Training in garden design was such an eye-opener for me. It was the reveal behind the curtain,' says the 39-year-old. 'I'd done gardening, but I had no idea about any of the simple design tricks we were taught.'
Wilkinson had previously worked in marketing but was craving a more creative path that would work with having a young family. She has since forged a career as a garden designer with her own studio based in Surrey. As well as over 400,000 followers on Instagram, she has a clutch of RHS medals, including two coveted People's Choice awards from RHS Chelsea Flower Show 2022 and RHS Hampton Court Flower show 2019. Part of the joy for her is working on fabulous designs for clients, but she also enjoys bringing garden design to a wider audience via her popular Instagram tutorials, 'so everyone can have a go'.
Her new book, How To Design A Garden, was written out of a desire to demystify some of the simple tricks she uses every day. 'They are so easily preventable,' she says. 'I don't want to do myself out of a job, but everyone really can have a beautiful garden.'
Here are seven mistakes she spots most frequently, and her advice for what to do instead.
1. Planting the boundaries
Narrow borders along fences are a cardinal sin, says Wilkinson. 'I totally understand why people do it. They're usually trying to keep maximum lawn space for kids or dogs, but I think what we've learnt as a studio is that even if your garden is quite compact, it's far better to hand more of it over to planting. You can't necessarily have a football pitch in a small urban garden; it's better to own that.'
From a garden design point of view, allowing space for more generous planting makes everything feel far more intentional. Wilkinson suggests playing with shape: 'Borders don't have to be straight lines down the side.'
If a client's garden is a classic rectangle with a patio by the house, she will always bring plants along the patio in between the paving and the lawn; that way, 'When you're inside looking out you're looking at plants before you're looking at the lawn. Lawn is a void, as is paving. Bringing plants in is such a simple trick that completely changes the dynamic of the garden by adding mass.'
She advocates for borders that are at least 1.5 to 2 metres: 'That's when you can start to get layers of plants. If you've only got 70cm, for example, you're only going to get one row of things, which is really not going to give you depth.'
Making the shed a focal point
'This is an absolute classic,' says Wilkinson. 'Most people have their kitchen sink under a window, overlooking the garden. But so often, you're looking out at a shed.'
Popping a shed at the end of the garden means the eye travels straight down to it. 'And they are rarely that beautiful,' points out Wilkinson.
As a solution, she always tries to tuck the shed to the side of the house if there's space. If there isn't, she will put the shed at the end of the garden and turn it 90 degrees, so the door is not facing the house. 'It means it's taking up less depth, and then we'll put a hedge in front of it.' Wilkinson loves evergreen yew and Portuguese laurel, which provide coverage in all seasons.
'Having a hedge allows you to use the last two metres of your garden as a utility space,' she adds. 'You can place your compost there, or anything ugly you want to hide away.' In front of the hedge she will plant a border: 'So now you've got this lovely focus point at the end of the garden.'
3. Not painting your fences dark
Painting sheds and fences dark was one of the first tricks Wilkinson learnt: 'And it blew my mind. I didn't see how it could work.'
It works, she says, because pale fences draw the eye, whereas darker fences blend into the background more easily. 'The point is to plant in front of it, so you won't even notice it. It's like a mount on a picture.' She will add wires to a black fence, for instance, so that climbers can grow up it. 'The goal is that you don't even notice that you've got a fence by the end of it.'
Wilkinson loves climbing hydrangea for shadier spots. And for the sun, she loves star jasmine. 'I love the scent it pumps out in May and June, and the evergreen leaves. It can be a bit sulky, but once it gets going it's great.'
Painting fences black – Railings by Farrow & Ball, which is a very dark blue black, is a favourite shade of hers – is also a cost-efficient way of unifying mismatched fences (although, she caveats, 'If it's not your fence, you do need permission to paint it').
Wilkinson also points out that dark fences are best in urban or suburban spaces: 'In the countryside we try to avoid fences altogether and have more hedging.'
4. Too much paving
If you love entertaining and have a large family or group of friends, the temptation is to think you need a large patio. 'The big mistake is that you end up with a great big sea right outside the house that runs the entire width of the house and looks like a furniture showroom,' says Wilkinson. In our desire for versatility, we can end up creating very hard spaces, 'Which is the opposite of what a garden should be.'
She encourages clients to divide paving into different 'rooms': a dining area, for example, will be wrapped in a border of plants so that it feels like a room and the plants act as a wall. 'We mix up the materials on the floor as well,' she says. 'We wouldn't just do an enormous sea of large-format paving; we try to delineate using a smaller format as well.'
If you already have a large patio you could try lifting some of it, or bring in large planting troughs to divide it up: 'Anything that brings in some verticality,' says Wilkinson. 'We will often bring in oversize pots with trees. That can feel a bit scary, but we're trying to bring in height.'
Another no-no is to pave all the way up to the fence: 'We always put planting between paving and a fence,' says Wilkinson.
5. Not paying attention to the light in your garden
It is a mistake that we've probably all made at some point: planting plants regardless of your conditions. Wilkinson says that a common mistake is to place plants such as lavender in the shade: 'Those Italian plants that I know a lot of the UK love, like olive trees and lavenders, get put in north-facing gardens, and then we wonder why they look really sad.'
She adds: 'I think a lot of us get very excited about sun planting, but shade planting is a bit more subdued and tends to be more greens and whites. It can be easy to ignore the fact you have shade and deep shade and put in roses and peonies, plants you love but that aren't suitable for those light conditions.'
Even so, Wilkinson professes to love a north-facing garden: 'It means you can sit in the shade and eat,' she says. 'And you can still have beautiful shade planting. People love hydrangeas, and they are plants that do pretty well in part shade, as do beautiful soft grasses such as Hakonechloa macra.'
6. Thinking too short-term
This is something Wilkinson knows about from her own experience as a parent; the tendency to design your garden around kids that grow up quickly.
'We will often get asked for climbing pits, sand pits and trampolines quite near the house in view, because obviously when your kids are small you want to watch them bounce on the trampoline – but it's very short term,' she says.
Wilkinson's children are now nine and 10. 'I don't need to supervise them all the time and I'd rather not stare at the trampoline,' she says.
Similarly, she encourages her clients to think about how they will use their garden over the next decade or even longer.
'If you've got a two-year-old, then fine. But if it is a forever home, then we always say: 'When they grow out of the climbing frame, what will be there?' Building gardens is expensive, so we want to do it once and do it right.'
7. Haphazard planting
Before she trained as a garden designer, Wilkinson would go to the garden centre and buy one thing that was in flower and looked good. Now, she says, 'It's really rare that we'd put one of something in a garden.'
Her studio is known for its repeated clusters of perennials. 'A lot of perennials are actually quite narrow and it would look nuts if one was sitting on its own,' she says. However, clustering and repetition are two things that unless you've been taught, you don't do, she says.
She advises trying to be restrained on your shopping list. 'It's a bit like going to the supermarket hungry. When you go to the garden centre you need that list. It feels over the top to go and buy 15 Salvia 'Caradonna' but that's sort of how many you need for it. Then you introduce them into the garden and repeat them.
'I don't want to be a killjoy, because gardening is so much about a love of plants,' she adds, 'but if you want it to be designed and thought-through then it's better to sit down and make a list to make sure you've got plants for each season. And if you say, 'I'm just going to have 15 plants that I cluster and repeat around', it looks so much more considered.'