It’s hard to believe anything in such a gentle hobby could be contentious, but it turns out even gardening is filled with misinformation, myths and so-called ‘old wives’ tales.’ From utterly useless slug deterrents to garden design traps that are actually making your garden look worse, we’ve rounded up nine of the biggest gardening lies out there and broken them down with the help of horticultural experts to get to the truth.
Lie #1: Astro-turf is lower maintenance than lawn
According to research conducted by Aviva in 2024, 21 per cent of UK homeowners had already switched or planned to swap their natural lawn for artificial grass. People believe artificial grass is lower maintenance than a traditional lawn - after all, it doesn’t need watering or mowing, it won’t go brown in a dry summer and it won’t need reseeding as it can’t die off.
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However, with the call to reduce our plastic consumption as much as possible, it seems strange that people would opt to coat their gardens in it. To add to its obvious environmental impact, it’s also not as low maintenance as you might think. “Astroturf requires sweeping or even vacuuming,” says Kate Bradbury, a writer and author specialising in wildlife gardening. “It needs replacing every few years as it degrades. Plus, you can't stand on it in hot weather, as it traps the sun's heat, so is completely impractical with hotter, drier summers,” she adds.
Another maintenance consideration is the additional cleaning if you have pets using the garden as a bathroom. The plastic turf requires much deeper cleaning to stop it from smelling and discolouring when animals are involved.
Additionally, it may not even prevent the ‘problems’ you were hoping to solve by installing fake grass. “Nature finds a way,” says RHS Horticultural Advisor Nick Turrell. “I’ve seen moss and weeds growing on the top of astro turf, because dust and detritus will settle in amongst the grass and then plants will grow on the top.”
Although it may provide instant impact, plastic turf is not a forever solution. A well-established lawn provides much better longevity and is better for the wildlife in your garden too. If grass seed won’t work for you, consider alternatives like a chamomile lawn or embrace some moss.
Lie #2: Add crocks to pots to improve drainage
Crocks are pieces of broken terracotta pot placed over the holes in the bottom of a planting pot. Traditionally, gardeners would always add crocks to the bottom of their pots. However, contrary to popular belief, this is not to improve drainage, but simply to stop the compost from falling out of the bottom and making a mess.
“It used to be the way that everybody did things,” says Nick. “Actually it’s not completely necessary. The only thing you need to do is put something on the hole to stop water and compost draining straight out. It can be cardboard or whatever you like.”
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There is also a misconception that you need many crocks at the bottom of the pot. “You don’t need a whole layer,” adds Nick. “Just one over that hole and that’s all it is. Otherwise, it can create air gaps which roots don’t like. So, at the RHS, we don’t do that anymore.” Such a simple trick, but as it turns out, nothing to do with improving drainage for the plant.
Lie #3: Copper, eggshells and coffee deter slugs
As the gardening industry moves away from pesticides, people have been looking for organic ways to deter slugs from eating their plants. Everything from coffee to eggshells has been touted as a slug repellent. Copper bands around the rim of pots deterring slugs has been a particularly persistent claim. However, Nick says this is “anecdotal, not something that has been scientifically proven”.
“I don’t think there is any science to back that up,” he adds. “I’ve seen slugs happily going over copper bands, looking at me with two fingers up almost.” As these bands aren’t harmful in any way to plants, then there is no reason that people can’t use them if they believe they work. “If some people swear by it then that’s terrific,” he says. “But I wouldn’t rely on it to protect your hostas.”
Instead of relying on quick fixes, plant extra in your garden and accept that some might become sacrificial plants.
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Lie #4: Watering when it’s sunny burns the leaves
Gardeners are often advised not to water when it’s sunny. Some people believe that this is because water on the plants magnifies sunlight and can burn the leaves.
“There is no real evidence to support the idea that watering in full sun can burn leaves,” says Nick. “However, it’s not a bad idea that people don’t water in midday sun because it’s an inefficient way to water – 40 per cent will evaporate in those conditions. So, it’s just good for people not to water at that time of day but nothing to do with scorching leaves,” he adds.
“First thing in the morning when it’s still cool is more efficient,” he says. “Water is now a very precious commodity and watering when its cooler allows water to penetrate down into the soil.”
Lie #5: Big borders make your garden look smaller
This is a classic myth that persists, and many beginner gardeners fall into the trap of thinking that narrow borders around a large lawn will make the space feel larger. However, the opposite is true.
Big planting beds will make your garden look much bigger than it is, by providing lots of interest and drawing the eye around the space. In small gardens, curved borders are particularly effective at making the space feel luxurious and big enough to explore.
Dutch design master Piet Oudolf is famed for creating large sweeping borders in spaces including RHS Garden Wisley and The High Line in New York. It’s safe to say that these planting beds have never made a garden feel small. Similarly, at Great Dixter, the Long Border overflows with planting, covering parts of the path in summer, to excellent effect.
Though most of us will be working on a much smaller scale, it is worth taking inspiration from these gardening greats and handing over more of our gardens to planting beds.
Lie #6: Weeds are harmful
The battle between weeds and gardeners has been long fought. Recently, attitudes have begun to shift away from killing these plants, but old habits die hard. If you ask Google, ‘Are weeds harmful to plants,’ the AI overview it provides will categorically tell you that, yes, they are.
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“I can’t think of a reason why weeds would be considered harmful,” says RHS Horticultural Advisor Nick Turrell. “They were all around long before cultivated plants were so they will have a place in the ecosystem.”
Reasons cited by Google that weeds are harmful include the plants competing for resources, providing shelter and being hosts for pests and diseases and physical damage such as smothering.
“Obviously things like Japanese knotweed can be a nuisance to humans,” adds Nick. “But I wouldn’t say it’s considered harmful.”
Kate Bradbury agrees. “The value of plants traditionally thought of as 'weeds' is finally being realised. Many provide excellent nectar and pollen opportunities for insects, while most also act as foodplants for caterpillars. Let them flourish at the back of your borders if you don't want them to be a centrepiece of your garden but do make space for them.”
It would be much more harmful to your garden to use herbicides to kill weeds than to embrace them as plants that are a part of your space.
Lie #7: Slugs and pests are the enemy
Much of traditional gardening teaching was about how to ‘deal with’ various pests in the garden. From slug pellets to bug-killing sprays, pesticides have been a stalwart of many gardening routines over the years.
However, times are changing and we all need to reframe our relationship with these creatures, which play an important role in the garden. “Seeing pests as the enemy is a very old-fashioned approach,” says Kate. “No garden wildlife is an 'enemy'; all are part of a working ecosystem and have their role in the garden.”
By killing insects, you are affecting the lifecycle of many other animals in your garden, from birds to frogs to hedgehogs. Planting a diversity of plants and accepting that some of them will be lost to slug damage or aphid infestation is a much more sustainable approach.
Most slugs don’t even eat garden plants, so when you set out to kill the creature eating your hostas you may well end up killing a whole host of slugs that were also enriching your soil and breaking down dead plant material. As plant ecologist Ken Thompson adds: “Slugs and other so-called pests are all part of the garden ecosystem, and any attempt to control them without damaging the rest of the ecosystem is doomed to failure.”
Lie #8: Peonies need ants to bloom
It was once thought among some gardeners that peonies needed ants to help open the flower buds. “I don’t think so,” says Nick. “I’ve seen plenty of peonies thriving without the ants.”
So how did this myth start? It is most likely caused by ants often being found on peonies before they bloom in search of nectar in the flower bud. “I don't know any evidence specifically linking peonies with ants,” says Ken. “Ants will steal nectar from flowers, and 'farm' aphids for their honeydew. They probably do both on peonies, but no more than on anything else.”
Gardeners must have observed that their peonies were often covered in ants and surmised that this helps them to bloom. But there is no evidence for this claim, and peonies seem to bloom perfectly well in the absence of ants too.
To grow peonies for perfect blooms, don’t focus on ants but instead be sure to choose a bright spot in the garden to plant them, and stake tall varieties when they reach about 15cm so that they don’t flop in wet weather.
Lie #9: Houseplants can prevent mould
The internet and social media are awash with claims that houseplants can help beat condensation and mould by reducing humidity in the air. Most of the articles online – if they cite any evidence at all – claim that houseplants can absorb moisture in the air through their leaves.
Sarah Gerrard-Jones, AKA The Plant Rescuer, told us: “I can categorically state that houseplants do not remove mould or condensation from a room. How do I know? Because I have hundreds of houseplants, condensation, and some mould in one of my rooms. I hope that tells you all you need to know about this myth.
“At the root of this being factually incorrect is science. Plants transpire – ie, they release water vapour into the air from tiny mouth-like holes on their leaves. They don't suck moisture or mould spores out of the air.”
Guy Barter, chief horticulturalist at the RHS, echoed Sarah’s comment. "Some internet sources suggest that plants absorb water thorough their leaves. This, I’m afraid, is fanciful. It would save a lot of watering were it true."
He points out that houseplants, if anything, could contribute to humidity. "Houseplants emit water vapour during transpiration, an unavoidable part of photosynthesis, necessary for the plant’s existence. This will contribute in a very small way to condensation in houses."
So unfortunately, houseplants won’t provide a quick solution to any mould problems you have in your home this winter. It is recommended to use a dehumidifier instead if the problem is particularly bad.
