COMMON PLANTING DESIGN MISTAKES
Most planting mistakes aren't about picking crap plants. They're about picking plants on a whim, not carefully considered for the border they're going into for the next ten years.
The garden centre is the worst place to plan a border. Everything's in flower, everything looks incredible sat together on the trolley, and none of that tells you what the bed looks like in November, or in year three when the thing you bought as a nice little shrub has tripled in size and is taking over the show.
Which is the entire point of a proper planting design — thinking about the border in every season, not just the one it was bought in.
1. Buying for one season
A border that's banging in June and bare for the other eleven months, because nothing was chosen for structure or winter interest.
2. Ignoring mature size
Plants get bought at the size they are in the pot, not the size they'll be in five years, and everything ends up overcrowded and fighting for light, with the strongest growers eventually bullying everything else out.
3. Picking for colour before conditions
A plant that wants full sun and good drainage will sulk, or die, in damp shade, no matter how much you liked the colour of the flower on the label.
4. Too much variety, not enough repetition
The other one worth naming: too much variety, not enough repetition. A border with one of everything reads as noise, not a design — fewer species, repeated properly through the space, almost always looks calmer and more intentional than a one-of-each shopping trolley. It's counterintuitive, because it feels like more variety should mean more interesting, but the eye reads repetition as order and a scattergun of single plants as clutter.
5. Not accounting for how light and seasons change things
Worth mentioning too: not accounting for how a garden actually changes hour to hour, not just season to season. A border planned entirely from a photo taken at midday in June won't account for how the light shifts, or how a spot that's baking hot in summer might be a frost pocket in winter — which quietly kills off plants that were never wrong for the garden, just wrong for that particular patch of it.
6. Ignoring maintenance
There's also a maintenance side to this that gets overlooked. Some planting schemes look wonderful in a photograph and need constant staking, dividing or cutting back to stay that way — which is fine if that's a job you enjoy, and a slow-motion disaster if it isn't. Choosing plants that suit the amount of upkeep you'll actually give them matters as much as choosing ones that suit the soil.
7. Not planning for what's happening underground
And one that's easy to miss entirely: not planning for what happens underground. Roots from an established tree or a boundary hedge can quietly compete with anything planted nearby for water and nutrients, which is why a border that thrived when it went in can start to struggle a few years later for no obvious reason above ground. It's worth walking a new border at different times of day, and thinking honestly about what's nearby below the surface, before committing to a planting plan that assumes the whole bed has equal access to water and light.
There's a simpler version of most of this that's worth remembering when you're standing in the garden centre with a trolley: ask what a plant is doing for you in November, not just in June. If the honest answer is "nothing," it's not necessarily a bad plant, it just needs pairing with something that carries the space once it's finished its moment. A border built entirely from summer stars, with nothing evergreen or structural holding it together, will always have a long stretch of the year where there's simply nothing to look at.
None of this is really about taste. It's about designing for the conditions and the whole year, not the plant you fell for on a sunny Saturday.