Gardening, George, Greenhouses, Grow Your Own

Greenhouses are a staple of English gardens and an aspiration for all serious home-growers. But how do greenhouses work and what benefits do they provide for your plants and vegetables?

How do greenhouses work

What is a greenhouse?

A greenhouse is an external structure for growing plants, primarily made of a transparent material like glass or polycarbonate panels. They’re used in professional agriculture for growing huge volumes of crops, as well as by enthusiasts in their own back gardens. Inside you get a stable, warm environment that makes cultivating fruit and vegetables much easier throughout the year.

How do greenhouses work?

Greenhouses work by letting in as much light as possible then trapping this as thermal energy. The transparent walls and roof of the greenhouse allow all the visible rays of sunlight to pass through. This light heats up the air and objects (like the plants and soil) inside the greenhouse. But the glass also acts as an insulator, so this heat is locked inside the structure, keeping the temperatures warm all through the day.

Greenhouses are great at moderating a stable temperature. Matter within the greenhouse like soil and water absorb the thermal energy from sunlight and release it slowly, so they keep the greenhouse warm even after the sun sets. If the greenhouse contains lots of soil, the iron content within this has high enough thermal mass to regulate the temperature in this way with gradual heating and cooling throughout the day. Since the greenhouse is a closed structure, there is no breeze to disperse the warm air.

So the temperature remains constant, generally much warmer than the cold snaps we face outside, and your plants stay happy. They get all the sunlight they need to grow healthily and are sheltered from any harsh weather.

What are greenhouses used for

What are greenhouses used for?

Greenhouses effectively allow you to cheat the weather. In Britain we often have unreliable seasons at best, with cold winters and short summers. With a greenhouse you can extend the growing season – for example by sowing seeds earlier and growing vegetables like French beans and cucumbers for most of the year. Outside they would get too cold, but in the greenhouse they are protected.

The warmer environment in the greenhouse also means you can grow plants maladapted to our climate. Exotic species, such as melons and sweet potatoes, can thrive under the hot glass and delicate plants that would normally die in the winter frosts can be kept safe.

What are the benefits of having a greenhouse?

  • You can extend the growing season.
  • You can keep crops safe from pests within the physical structure, and so minimise the use of chemical pesticides you need to spray on produce.
  • You will protect plants from excessive temperatures (both cold and hot) and extreme variations in weather.
  • A greenhouse offers protection from strong winds which can damage delicate plants.
  • Shelter from rain and snow allows you to manually regulate how much water each plant is getting. This can be made easier with irrigation systems.
  • Temperatures can also be regulated with ventilation systems like auto vents to open windows and let air in, or shading to reduce light getting in during the peak of summer.
  • You can grow plants that wouldn’t normally survive in your climate.

Benefits of a greenhouse

Tips for keeping plants healthy in a greenhouse

While your plants will be kept warm and protected from the elements, you need to make sure they still get all that they need. Since they won’t receive water naturally from rain, you must remember to water regularly or set up an irrigation system to do this for you. It’s also worth setting up greenhouse guttering and a waterbutt to harvest rain falling on the roof.

During the summer months, the greenhouse can sometimes get too hot, which isn’t healthy for everything growing. So be sure to open a window or door if it gets too stuffy. You can also use a ventilation system like louvre windows or automatic vent arms to manage this for you. If excessive sunlight is causing the greenhouse to heat up uncontrollably, then hanging or spraying temporary shading on the roof windows can alleviate this.

Your greenhouse will also need taking care of to make sure it’s at its best year after year. This includes things like an annual deep clean, sterilising pots and checking for damage. You can read more in our greenhouse maintenance guide. Also make sure that you keep on top of pest control in your greenhouse.

Lacewing greenhouse

Different types of greenhouse

Thankfully there’s not just one type of greenhouse to satisfy all gardeners. If you have space, then it’s worth getting the biggest freestanding one you can to maximise your growing area. But if space is limited then you can get a lean-to greenhouse attached to the side of your house, which offers the same robust frame and panels. For allotments and patio gardening, mini greenhouses and cold frames provide very compact space for crops, and can be portable too.

Read more about how to choose your greenhouse.

So we hope you now have a better understanding of how greenhouses work and why they’re such an invaluable treat for hobby gardeners and pros alike. If you’re interested in buying one for yourself, Primrose has a great range of high quality greenhouses available.

George at PrimroseGeorge works in the Primrose marketing team. As a lover of all things filmic, he also gets involved with our TV ads and web videos.

George’s idea of the perfect time in the garden is a long afternoon sitting in the shade with a good book. A cool breeze, peace and quiet… But of course, he’s usually disturbed by his energetic wire fox terrier, Poppy!

He writes about his misadventures in repotting plants and new discoveries about cat repellers.

See all of George’s posts.

George, Greenhouses, How To, Pest Advice, Pest Control, Slugs & Snails, Spiders

Greenhouse Pest Control

Greenhouses are wonderful tools for keen gardeners, offering a much needed space to tend to gardening projects outside of the usual summer season. But while protecting your plants from the elements, greenhouses can also be prone to sheltering pests and diseases that will ruin all your hard work. Armed with our top greenhouse pest control tips, you should be well equipped to give your plants the best protection possible.

1. Keep your greenhouse clean

As with any form of disease or pest prevention, cleanliness is the number one priority. As part of your general upkeep, it’s worth thoroughly emptying and cleaning out your greenhouse once a year. This involves washing down the windows and surfaces, hosing off the floors and cleansing all the pots. Doing this should give you a fresh, pest-free start for growing each year.

2. Inspect your plants

It’s vital to check over all your plants before they enter the greenhouse in order to prevent pests spreading inside. Just as flowers and crops love the warmth of a greenhouse so too do bugs, and they multiply in the heat. So give any new plants a thorough inspection for signs of insects or larvae on the leaves or stem before bringing them inside.

3. Disinfect your tools

Most gardeners will regularly use the same tools all round the garden, transporting them around the shed, flowerbeds, lawn, vegetable patch, compost heap and greenhouse. This means they can pick up pests from the soil outside and infest the plants inside the greenhouse. So to be extra careful, it’s worth giving your spades, trowels and other tools a good clean every now and again – a soak in soapy water should do fine.

4. Use insect catchers

Chances are, insects will always find a way into your greenhouse. Catch them where they fly, with simple greenhouse pest control products, like hanging fly papers and wasp traps, or using spider spray at the door.

5. Use netting

Obviously, greenhouses need good ventilation and it’s never worth sealing them up completely to stop incoming pests. But you can easily cut down on the number of large flying insects entering by hanging netting across open windows or other vent points.

6. Move pots outside in the heat

In the summer months, greenhouses can often become hot and dry throughout the daytime. Moving potted plants outdoors not only helps cool them down but also reduces the build up of spider mites on the plants. Spider mites increase rapidly in number in dry heat so it’s worth keeping the greenhouse ventilated and also using a mister to keep the humidity up. If you’re going out for the day a good trick is to dowse the floor with water, which will evaporate into the air throughout the rest of the day.

7. Use potting soil

Often regular soil from the garden will be packed full of creepy crawlies, insect eggs and other pests. So for the container plants in the greenhouse, it’s a good idea to pot them in shop-bought potting soil or compost. This should be sterilised free from any pests or diseases and well as being rich in nutrients to help the plants grow.

8. Rotate crops

If you plant directly into the ground inside your greenhouse, clearly you won’t have as much control over the spread of potential pests within that soil. A method of combatting this is crop rotation – each year vary what type of plant you are growing in that piece of ground. This tends to prevent the buildup of pests in the soil, as similar plants usually encourage the same types of pest.

9. Freeze the pests

This is an extreme measure that you could perform once a year if you believe your greenhouse is truly infested. During the winter, allow your greenhouse to enter a chilling period by opening up all the doors and windows for a day or two. The temperature will drop right down, killing off any pests inside, including their eggs and larvae. As long as it’s not cold for too long, the plants should survive this. Obviously, any tropical plants or those that require constant warmth should not be left out for this.

10. Use biological pest control

Many common greenhouse pests, such as vine weevil grubs, whitefly and spider mites can be fought with biological control. Each pest has a corresponding organism that you can introduce to the infested area and it will feed on the pest, keeping its population under control. If the pest is eliminated then the control dies out too due to lack of food source, so you don’t need to worry about them destroying the plants instead. Some of these biological controls are available to purchase.

Hopefully by putting these tips into practice, your greenhouse will remain pest-free and your plants will thrive. Let us know how you get on or if you have any greenhouse pest control advice of your own!

George at PrimroseGeorge works in the Primrose marketing team. As a lover of all things filmic, he also gets involved with our TV ads and web videos.

George’s idea of the perfect time in the garden is a long afternoon sitting in the shade with a good book. A cool breeze, peace and quiet… But of course, he’s usually disturbed by his energetic wire fox terrier, Poppy!

He writes about his misadventures in repotting plants and new discoveries about cat repellers.

See all of George’s posts.

Awnings, Barbecues, Bird Baths, Cat, Celebrations And Holidays, Decoration, Easter, Garden Furniture, Gardening, Greenhouses, Lighting, Marquees, Newsletter, Outdoor Heating, Planters, Sail Shades, Toad Hall Garden Centre, Water Features

Happy Easter from Primrose!

Whether you’re celebrating with family or just relaxing, we hope you’ll have a fantastic time this Easter holiday.

If you’re looking for a day out this Easter and are local to the Henley-on-Thames area, we’d love to see you stop by our new concession area at Toad Hall garden centre. We’ve also got a voucher for a free tea or coffee on us. Read more about it in our blogpost.

Still missing some essential items to make your garden look as beautiful as it deserves to be? Take a look at our popular categories below to get it delivered for next weekend which is looking to be a hot one!

Over 270 Greenhouses Over 2500 Plants Over 1100 Planters
Over 640 Awnings Over 135 Barbecues Over 1300 Garden Furniture items
Over 180 Shade Sails Over 200 Outdoor Heaters Over 900 Water Features
Over 160 Garden Lights Over 250 Garden Hand Tools Over 25 Marquees

Win a Cadac Gas BBQ worth £450!

wedding-meCat works in the marketing team and is responsible for online marketing, social media and the newsletter.

She spends most of her time reading about a variety of interesting facts, such as oddly named Canadian towns, obscure holidays and unusual gardening.

She mostly writes about Primrose news and current events.

See all of Cat’s posts.

Barbecues, Cat, Clocks, Garden Furniture, Garden Screening, Greenhouses, Sail Shades, Toad Hall Garden Centre

Primrose at Toad Hall garden centre

We are now in Toad Hall Garden Centre in Henley-on Thames!

We’re proud to announce the launch of our large concession area within the Toad Hall garden centre in Henley-on-Thames.

Come and find a selection of our products from garden furniture to barbecues, greenhouses to garden screening, shade sails to clocks. It’s perfect to see some of our most popular products before placing the order for convenient home delivery. 

Have a free tea or coffee on Primrose whilst you browse. Simply print the below voucher and take it with you. Voucher valid until 22nd April 2014.

Toad Hall coffee coupon

wedding-meCat works in the marketing team and is responsible for online marketing, social media and the newsletter.

She spends most of her time reading about a variety of interesting facts, such as oddly named Canadian towns, obscure holidays and unusual gardening.

She mostly writes about Primrose news and current events.

See all of Cat’s posts.

Share!