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Having a polytunnel is already a good preventative measure for larger pests such as birds or rabbits, as a polytunnel will prove too difficult to get in and so will stop them in their tracks, but there are smaller pests that will find their way in. If you’re keeping the big pests out of your polytunnel, the next step is making sure that the environment inside the structure isn’t overly inviting for smaller critters.

One of the best ways to keep them away is simply to keep your polytunnel clean and well-maintained. Clean out any old leaves and weeds as these will attract pests and can hold diseases that are harmful to any crops you may be growing. Whilst polytunnels are a great way to store any of your gardening equipment, it is important to remember to clear out any old pots, trays and sacks of compost to prevent the build-up of bacteria and homes for pests to gather virtually undetected.

Slugs and Snails

The most common pests that you will have to deal with attacking your crops are snails and slugs and unfortunately are considered to be the most persistent. A single slug can demolish a row of seedlings in a night if left to their own devices, so this is the pest that you need to be the most vigilant with. To begin with, slugs and snails are attracted to damp conditions so where possible try to water your plants in the mornings rather than the evening in order to dissuade these pests from eating your crops. Follow this up by going on a slug clearance session in the evening to dispose of any attempting to get to your crops.

One of the most popular deterrents for these pests are ‘beer traps’: These are incredibly easy to make yourself. All you’ll need is a glass or plastic carton and bury it into the ground so that half of it is sticking out and then pour beer into the container. Place these around the plants that are most at risk and the slugs and snails will be attracted to the beer, climb into the containers rather than towards your plants and once in there they can’t get out.

Another alternative is to sprinkle dry crushed eggshells around your at-risk plants as slugs and snails will always avoid crawling over dry ground.

Aphids and Whitefly

Aphids and whiteflies focus on young plants, weakening them so that they die easily when fully grown. These are the type of pests that might tempt you to use chemical deterrents but if treated quickly enough when they first arrive then the damage can be reduced drastically. Ladybirds and lacewings are natural predators of aphids but are also very useful for pollinating your plants. Leave a couple of vents and doorways ajar and these predators will find their own way into your polytunnels to rid you of these tiny pests. A single ladybird can eat up to five thousand aphids in its lifetime, so they really are invaluable natural defences for your crops.

Companion planting is also useful when it comes to curbing the damage done by aphids and whiteflies. Planting French marigolds around your at-risk plants will deter aphids from latching onto them due to the strong scent coming from the marigolds. If you use these methods early enough after spotting the pests then there’s no need to resort to harsh chemical alternatives.

Brassica Pests

Any gardener who has experience growing brassicas can tell you how susceptible they are to pest infestation; from root flies to birds and butterflies so it is important to plan around this before planting them. As with any pest, preventative techniques are always better than trying to rectify the problem after it has taken hold.

Northern Polytunnels sell a range of fruit and veg cages that are available in a number of widths and lengths to suit any requirements. These cages consist of the same high-strength galvanised steel tubes that we are known for with our polytunnels and are 30% stronger than other suppliers on the market. The cages are fitted with strong polypropylene netting to keep out the birds and rabbits with cable ties so that they are easy to remove in the winter months.

We also offer the option of adding anti-butterfly netting to our fruit cages to help protect your brassicas from pests. For more information about our fruit and veg cages please send us an email to or give us a call on 01282 873120.

If you have any pest control methods that have worked for you, please feel free to share them with our gardening community on FacebookTwitter or Instagram.