The Importance of Proper Greenhouse Ventilation

greenhouse ventilation open window

Proper greenhouse ventilation is essential for your plants’ wellbeing

Gardening enthusiast and exotic plant lover Clive Harris of DIY Garden shares his knowledge on why greenhouse ventilation is so important.

Many novice gardeners are afraid of greenhouses, considering them high-maintenance mediums for demanding plants. However, modern advances have made greenhouse cultivation a cinch compared to previously, meaning you can now harvest your home-grown spoils with minimal cost, time and effort.

Temperatures inside a hothouse can rise more than 15% higher than outside, creating the ideal environment for producing exotic species that generally grow in hotter climates. This extra heat also provides the perfect conditions for nurturing your seedlings during winter, giving them a head start for the coming season.

Why Is Greenhouse Ventilation So Important?

Ventilate your greenhouse so that plants don’t bake in the summer heat!

Imagine being locked inside a hot car with the windows up on a sweltering summer day. Without ventilation, this is what your plants and vegetables are exposed to. Even the most tropical species will suffer in extreme heat, risking dehydration, leaf scorch and sun-flag. Any temperature over 27°C has the potential to damage your crops.

Ventilation has several benefits. As well as offering greater control over the internal temperature and humidity, it also increases airflow which is crucial for effective photosynthesis and pollination.

There are two types of ventilation systems – passive and powered. Passive or natural systems are the most common type found in small greenhouses. They use a series of ridge and sidewall vents which help to draw cool air in and dissipate the heat. In high summer, the greenhouse door can be opened to give extra ventilation and airflow.

Traditional powered mechanical ventilation systems involve the use of exhaust and circulation fans to maintain an ideal atmosphere inside the greenhouse.

However, I’m a huge fan of automatic ventilation systems as they use solar energy to automatically open the vents. No electrically required, and 100% environmentally friendly!

 Maintaining Optimal Greenhouse Conditions

Proper shading will help lower the temperature in the summer

Greenhouses are prone to overheating between spring and autumn, so keeping a close eye on the environment is vital for the survival of your harvest. Constant plant patrol sounds tedious, especially during summer months, so it’s just as well that technology has made it infinitely easier for the modern horticulturist.

Back in the good old days, a gardener would need to traipse back and forth many times a day in hot weather to check and adjust the temperature in their greenhouse. Thankfully, the advent of portable weather stations means the temperature can now be monitored remotely via smartphone.

Opening and closing the vents is another chore that has become effortless. Solar powered and heat sensitive vent openers are now available which automatically release once the temperature reaches a certain point.

Adequate shading will help to keep your plants cool in the scorching summer heat. Fit blinds to the exterior or interior of your hothouse to avoid overheating. A cheaper option to blinds is shade netting which works on a similar principle. For a quick and easy solution, shading paint can be applied to the exterior of the panes to prevent heat penetrating the glass. This can then be washed off once the weather becomes cooler.

During the hottest months, it is crucial to sustain humidity within the greenhouse. This can be done by damping down the interior regularly.

Contemporary greenhouse gardening has become straightforward and stress-free, meaning there’s no longer any reason to avoid those shiny glass panes. You’ll be on your way to prizewinning hothouse flowers in no time!


Find out more about growing under glass at our dedicated greenhouses hub page.

Surprising Household Products That Benefit Your Garden

Reduce, reuse, recycle- it’s a phrase that has been drummed into everyone in the last decade. Repurposing in the garden is a hot trend at the moment, and saving money isn’t the only benefit. Your garden is an ecological haven, so it makes sense to use natural products wherever possible, keeping harsh chemical fertilizers and pesticides to a minimum (something also worth bearing in mind if you have little hands helping out).

Clive Harris, a keen gardener from Essex shares his best tips for keeping your garden environmentally friendly, as well as saving you time, money and a trip to the local garden centre. You can see his personal gardening blog here –

Most households use an organic waste bin nowadays, and if you’re super savvy, you will have your own composting bin, but there are a few food waste products that yield better results when used directly in your garden.

composting waste

Banana Peel
Banana peel is an excellent source of potassium, phosphorous and magnesium, making it an ideal fertilizer. Chopped peel can be added directly to your garden for a nutritional boost. Soaking banana peel in water for at least 48 hours will give a fertilizing solution that can be sprayed directly on to plants and flowers. To give your perennials the ultimate start in life, line your bed trenches with whole banana skins before planting. This works exceptionally well for roses too!

Made of calcium carbonate, eggshells are a great way of providing calcium to your soil and plants. They need to be rinsed and dried before being added to your garden, otherwise you might find them attracting unwanted attention from passing animals and pests. They should be crushed or ground before mixing into the soil. It can take months for eggshells to break down enough to be absorbed by plant roots, so the best time to spread them in your beds is autumn and early spring.

Coffee Grounds
Used coffee grounds are rich in nitrogen, meaning they are terrific for enriching the soil in your flower beds. Unwashed, they are acidic and will help to balance the PH of your soil. However, if using coffee grounds around vegetation that doesn’t tolerate acid very well (such as tomato plants etc), rinsing them first will neutralize the acidity. Coffee grounds can be added directly to the soil in your garden, making it a quick and easy fertilizing option.

Tackle Those Pesky Predators

There are 2 types of pests that pose a threat your garden- wildlife such as insects or prowling animals, and plant diseases caused by bacteria, fungi and viruses. Shop bought pesticides and animal deterrents are a quick fix, but can be harsh and need to be used with extreme caution, especially in gardens where children and domestic animals are passing through. However, there are some safer, gentler options that can be used to the same effect as commercial garden products to ensure that your plants remain healthy and thriving.


Plant fungus giving you a headache? Aspirin is fantastic at preventing fungal diseases such as mildew and black spot. Simply crush an aspirin tablet and dissolve in a gallon of water. Use the solution to spray your plants every few weeks to guarantee they stay mould free.

Surprisingly, regular old shampoo makes a great insecticide. Mix 2.5 tablespoons of shampoo with 2.5 tablespoons of cooking oil and add to a gallon of water. Use the solution to spray on pests such as aphids. Plant leaves should be rinsed a few hours after application to prevent damage. This also works well using dishwashing liquid instead of shampoo.

Mix even parts of milk and water and spray on tomato plants to prevent dry end rot. Putting crushed eggshells into the planting hole will have the same effect.

As it turns out, us humans aren’t the only one who fancy a cold one in the garden during summer! Slugs and snails are highly attracted to the frothy goodness of beer, making it the perfect distraction to drag them away from your vegetables and flowers. Half-fill an empty jam jar with lager and dig a trench so that the lip of the jar is flush with the ground. The pests will gravitate to the jar and die a happy death.

Playing your dodgy old 90’s pop tracks at full blast will definitely keep flying predators at bay. However, if you’re finally ready to relinquish them, old cds are a more effective deterrent when used as a type of scarecrow to keep larger pesky birds away from your seeds and vegetables. String a few cds together and hang near your beds at a position where they will catch direct sunlight to keep pigeons and other scavengers away. This trick also works great as a cat deterrent.

cd scarecrow

Plastic Bottles
Plastic bottles half filled with water will stop cats digging up and soiling your flower beds. The water in the bottles casts a reflection that frightens the felines away.

From eggshells to aspirin, and even old Spice Girls cds, it is astonishing to see how household products and by-products can benefit your garden in a multitude of ways, saving you money while helping the environment at the same time. There’s no better place to start your recycling kick than in the garden!

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