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Keeping Your Greenhouse Pest-Free: Top Tips for a Healthy Garden

Growing in a greenhouse this summer but worried about pests? Pests such as whiteflies and aphids can cause havoc to your seedlings and vegetable crops.

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Growing in a greenhouse this summer but worried about pests? Pests such as whiteflies and aphids can cause havoc to your seedlings and vegetable crops. The warm, humid environment that encourages plants to grow is also a paradise for many nuisance critters. Pests can quickly take over your greenhouse, damaging your plants and leaving you with a low yield at the end of the season or even dying species.

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Luckily, it’s easy to control pests. All it takes is a little monitoring and action, and your greenhouse will be bug-free in no time. Read on for Rhino Greenhouse Direct’s top ways to identify and rectify problems.

How to Identify Common Greenhouse Pests

One good thing is that, if you have pests, you can spot them easily. If you notice foliage beginning to wilt or discolour or a honey-type residue left on your plants, these could be sure signs that you have a pest problem.

Here are the main greenhouse pests and how you can identify them…

  • Red spider mites – while these small mites are almost invisible to the naked eye, they leave behind a fine webbing over your plants. You can also look on the underside of the plant’s leaves for small white eggs laid by spider mites.
  • Whitefly – These will be easy to spot as they usually multiply quickly and stick together. They look small, white and triangular and will be spotted on your plant’s foliage. If you have an infestation, you might notice that your plants are wilting.
  • Aphids – These small green creatures need to be stopped quickly – if left untreated, an aphid infestation can quickly multiply, and they’ll zap your plants of essential nutrients. Look out for leaves curling inwards and a sticky sap – that soon turns black – being left behind.
  • Fungus gnats – Another fast-multiplying pest, fungus gnats can take over a greenhouse in as little as a week. You’ll spot these small flies hovering above the soil. If you suspect you might have them, simply disturb the soil and see if they fly upwards.

How to Prevent Pest Infestations

Obviously, the preferred action is to prevent an infestation before it happens. There are several ways to make sure these tiny nuisances don’t take over your greenhouse.

Here are some ways that you can prevent a pest infestation…

  • Keep your greenhouse clean – A clean greenhouse will deter infestations from starting up. You should do a deep clean once a year – preferably more – wiping down all tools and surfaces with warm water and insecticidal soap. Throughout the year, keep the space free of plant debris.
  • Invest in shop-bought compost – Not only will this give your plants all of the essential nutrients they need, but it’s also sure to be free of pests. If you use compost from your garden, you can’t be sure what pests you’re bringing in to flourish within the greenhouse environment.
  • Create traps – You’ll find pest traps at any DIY shop that you can easily set yourself to deter small bugs from making your greenhouse home. These include sticky fly paper and slug pellets.
  • Create boundaries – Use plant netting and net screens to stop pests from entering your greenhouse and landing on your plants.
  • Keep it cool – It might sound detrimental to the purpose of a greenhouse, but pests flourish in the hottest months of the year. By wetting the floor of your greenhouse and letting the water evaporate, you can cool the temperature, deterring some pests from multiplying. It’s important not to let pools of water sit as this can attract more bugs.
  • Ventilate regularly – As well as controlling the temperature, you’ll want to ventilate your greenhouse well. This helps control the levels of humidity, which could see pests thrive. Leave a window open for a couple of days but ensure it is secure with netting to prevent bugs from

How to Control Pests Naturally

When it comes to controlling pests, there are natural methods you can take up. These won’t harm helpful pollinators that are simply going about their work in your greenhouse without leaving a trace.

Here are some natural methods of pest control…

  • Companion planting – This is when you plant two species close to each other to attract helpful bugs. Plants such as marigolds, mints and tagetes will attract good beetles like ladybugs and lacewings. These eat aphids and whiteflies, preventing infestation.
  • Use a neem spray – Neem is taken from the seed of the neem fruit tree and can help to stop pests from developing by disrupting their hormonal systems. Simply spray on the leaves of your plant as a natural insecticide. Note: neem is toxic to pets so ensure they stay out of the greenhouse while the substance dries.
Spring plants in flower


How to Monitor and Respond to Pest Infestations

As many pests, such as aphids and whiteflies, can multiply very quickly, it’s important to monitor your greenhouse. You should act at the first sign of a pest problem before it leads to an infestation, which could lower your yield or even kill your plants.

Here are a few ways to monitor for pests…

  • Check your leaves – If you have a pest problem, your foliage will likely suffer first. Look out for signs such as wilting, discoloured or curling leaves.
  • Look for residue – Some pests, such as aphids, leave behind a sticky residue. You’ll notice this on the top of your plants’ leaves, and it could be white, black or transparent.
  • Check for eggs – It’s worth looking for eggs left by pests regularly. These will usually be laid on the underside of the leaves, close to the stem, and will be easily visible.
  • Monitor the soil – Pests such as gnats live close to the soil. To check for these, simply give the soil a dig, if you have a gnat problem, you’ll see them disperse.

If you notice any of these signs, act quickly. For eggs, you can simply wipe them away with a clean cloth. Hang sticky traps for flies and gnats and try a natural pesticidal spray for aphids. You should also monitor your greenhouse’s climate, ventilating it regularly and cooling it down during the peak months of summer.

Keeping your greenhouse free of pests is vital if you want to see your plants grow healthy and strong. If you’re growing veggies, you can ensure a large yield by stopping pests from thriving in your greenhouse, too.

Remember, if you think you have a pest problem, act quickly. During the hotter months, in particular, pests can soon get out of control. With a little time and attention, you can keep your space free of nuisances and reap the rewards of your hard work.

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