5 ways to banish garden pests without chemicals – approved by an expert

The garden pests you encounter can vary from year to year, depending on the weather. A damp spring is heaven for slugs and snails, while a warm summer can see insect pests such as blackfly covering our plants.

There’s no need to reach for a pesticide bottle, as chemical sprays can also kill the predators that help keep pests under control. Instead, there are plenty of practical ways to protect your plants, from putting up physical barriers to letting natural predators do the work for you.

Below, we explain some simple ways to protect your plants and keep common pests under control, with practical advice from the experts at Which? Gardening.

1. Know your friends

Many garden pests have a nemesis that will eat them. Unfortunately, many of us don’t recognise these natural predators and can end up killing them alongside the bugs we actually want to get rid of.

Common ones to look out for include ladybird larvae and hoverfly larvae, both of which do a fantastic job of eating aphids and other small pests (Also see: How to get rid of aphids). Avoid using pesticides, as these can unintentionally kill these helpful insects too.

Ladybird larvae look very different from the familiar red adult ladybirds, so they're easy to mistake for pests. They're usually dark grey or black with orange markings and have long, segmented bodies. Hoverfly larvae are less distinctive and look a little like small green or brown caterpillars.

If you spot either on a plant covered in aphids, leave them to it. Giving these natural predators a chance to get to work can help keep pest numbers under control without you having to intervene.

If you're spending time checking plants and tackling pests at ground level, see our guide to the best garden kneelers.

2. Cover up

A simple way to keep veg pest-free is to grow it under fine insect-proof mesh, such as Enviromesh. This creates a physical barrier that stops unwanted visitors from reaching your crops – it's particularly useful for veg that's regularly targeted by flying pests. The key is to get the mesh in place early, before insects have a chance to lay their eggs.

Put the mesh on as soon as you plant your veg and keep it in place until harvest. For taller crops, you can lay it over hoops to give plants plenty of room to grow. Make sure you secure the edges carefully, as even a small gap can give determined pests a way in.

Check the mesh occasionally for holes or tears and make sure growing plants haven't pushed up the edges. Use large stones or bricks to keep it securely in place, rather than pushing pegs through the mesh, which could cause it to rip.

If you're interested in growing your own veg but don't know where to start, read our guide to the easiest vegetables to grow for beginners.

3. Buy in some help

Biological control is an effective way of using the power of natural predators to control pests. It’s sold online by specialist suppliers, such as Dragonfli and Green Gardener.

Depending on the problem you're dealing with, you can buy microscopic nematodes, predatory mites or other beneficial creatures that target specific pests without harming your plants.

Timing is important, as you're dealing with living organisms that need the right conditions to work effectively. Specialist suppliers can advise on the best time to use them, including the temperature and conditions they need.

It's worth identifying the pest before ordering anything, rather than buying a biological control and hoping for the best. Follow the supplier's instructions carefully too, particularly when it comes to storage and application.

Depending on the type, biological controls can be mixed with water and applied to the soil using a watering can, or are supplied in sachets. They can be used to tackle common pests including slugs, mealybugs and spider mites.

If you need a new one, see our guide to the best watering cans to find out which impressed in our tests.

4. Take away their hiding places

Many pests shelter in our gardens, emerging when conditions suit them. Slugs in particular love the cool, damp conditions created by wooden bed edges, so consider removing these if they’ve started to rot.

It's worth checking other likely hiding spots too. Look underneath pots, containers and pieces of wood, particularly if you're seeing lots of slug or snail damage but can't work out where they're coming from.

Snails often shelter in pots and plant trays, as well as in tucked-away spots such as between the leaves of phormiums. Regularly checking these areas means you can remove them before they make a meal of nearby plants. If they're proving especially troublesome in your garden, see our guide on how to get rid of slugs and snails.

Many pests also overwinter in greenhouses, so a thorough clean-up in autumn can help prevent problems the following year. Clear away dead leaves and old plant material, clean pots and trays and give the greenhouse a good tidy to remove places where pests can shelter until temperatures rise again.

Not sure what's attacking your plants? You can ask our gardening experts for advice tailored to your garden.

5. Don’t be fooled by social media

You’ll often see posts recommending neem oil to control garden pests, but it isn’t authorised for use as a pesticide in the UK because of concerns about its effects on human health.

Neem oil shouldn’t be sold for use as a pesticide in the UK, and neither should pesticide products containing its active ingredient, azadirachtin. It is legal to use in parts of the USA, which is one reason you may see it recommended online.

This is a good example of why you should be cautious with gardening advice on social media. Tips shared by gardeners overseas won't necessarily reflect which pesticide products are authorised for use in the UK.

For smaller pest problems, a simple approach may be all that's needed. If you have a small infestation of aphids, for example, physically removing them can be quicker than reaching for a treatment. Check the undersides of leaves and new shoots, where they're often clustered together.

Not every pest is a problem

'Don't panic if you spot the occasional pest. A completely pest-free garden isn't realistic, plus leaving some insects around gives natural predators a food source. The aim is to stop pest numbers getting high enough to cause serious damage to your plants.

'Check your plants regularly so you can spot problems early, but remember that a few chewed leaves or a small cluster of aphids aren't necessarily cause for concern. Give predators such as ladybirds, hoverflies and birds a chance to tackle them first, and only step in if pests start getting out of hand.'

Ceri Thomas, Which? Gardening editor

Which? Best Buy gardening gloves

For pests that are easy to remove by hand, a good pair of gardening gloves can make the job a little less unpleasant. You can squash small infestations of aphids or pick off slugs and snails on a damp evening, when they’re likely to be most active.

We’ve tested gardening gloves for comfort, durability and protection while carrying out common gardening tasks.

Of the gardening gloves we've tested, these are among the best:

Which? members can log in to view our Best Buy gardening gloves. If you're not a member, join Which? to get instant access.

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