Garden Structures

How To Grow Vegetables In A Greenhouse All Year Round

bell pepper plants growing in a greenhouse
Written by Chris Briggs

Growing your own vegetables comes with plenty of benefits – they’re more nutritious, free of pesticides, they help you to save money and are better for the environment. Owning a greenhouse enables you to easily grow vegetables throughout the year.

If you want to grow vegetables in your greenhouse all year long, then you need to know how to deal with the unique challenges that each season brings.

In this guide, we’ll be covering every aspect of growing vegetables throughout the year, including the best types of vegetables to grow depending on the season and how to maintain your greenhouse at different times of the year.

Let’s start by looking at the different types of greenhouses you can grow vegetables in.

Types of Greenhouses

Standard greenhouse

A standard, glass greenhouse is an ideal place to grow vegetables since they’re designed to maintain a stable temperature regardless of the weather conditions. Having a greenhouse enables you to protect your plants from the harsh weather during winter, while still giving you the option to move them to your garden during the spring and summer.

A woman exiting a standard glass greenhouse with plants in hand
A standard glass greenhouse – ideal for growing vegetables

The downside to a standard greenhouse is that they can be very costly to build, and you will need quite a bit of space in your garden to accommodate one.  

Cold frame greenhouse

A cold frame greenhouse uses solar energy to create a stable climate for growing vegetables. Cold frame greenhouses are significantly cooler than a traditional greenhouse, while still enabling you to protect your vegetables from wind and frost.

Polytunnel

A polytunnel consists of a steel frame that’s covered with polythene in order to create a protective environment for growing plants and vegetables. Sunlight can still get through to the plants, but the cover is strong enough to provide protection from the elements.

The advantage of polytunnels compared to traditional greenhouses is they’re much cheaper and significantly easier to set up. Most people would be able to set up a polytunnel without too much trouble and you can buy kits that come with everything you need included.

Growing Tips

Growing vegetables successfully means knowing the best time to plant, how to care for your plants as they’re growing and what steps to take in order to make your greenhouse an ideal environment.

close up of a tomato hanging from a vine
Tomatoes are a very popular vegetable grown by greenhouse owners  

Starting off seeds

When you first plant seeds, it’s not a bad idea to grow them indoors using a propagator. This is particularly true when you’re sowing during winter. You can sow them and keep them indoors in containers until they germinate and then move them to your greenhouse as they get bigger.

Best Time To Sow

The best time to sow will depend on the type of vegetables you’re growing. Below are the best types of vegetables to grow for each season.

Winter

Vegetables that are frost-tolerant and can thrive in lower temperatures are best sown during the winter months. Vegetables that would be suitable for sowing in winter are lettuce, cabbage, spinach and broccoli.

You can plant these vegetables either directly outdoors, roughly a month before the last frost is expected; or you can grow them earlier in your greenhouse or polytunnel.

Spring

Spring would be an ideal time to sow plants that cannot survive frost damage and need more exposure to sunlight to thrive. Cucumbers are an obvious example. You can sow these types of vegetables either indoors or if you prefer, in your greenhouse, and then move them outdoors once summer begins.

Summer

When summer comes around, it’s a good idea to move the plants you’ve been growing in your greenhouse during winter and spring outdoors. This will allow them to benefit from direct exposure to sunlight and rainwater, while also giving you more room to grow new plants.

The best type of plants to grow during summer would be those that thrive in higher temperatures, such as tomatoes and peppers.

Autumn

Autumn is an ideal time to start growing new vegetables, particularly ones that are tolerant to the cold. Vegetables such as radishes, kale, garlic, beetroot, broccoli and cauliflower are all suitable for growing at this time of the year.

Providing you look after them properly, they should be ready to eat in time for Christmas.

When to move plants outdoors

Many growers will start growing their vegetables either indoors or in their greenhouse during the autumn or winter. This makes sense, since you can protect them from extreme cold and frost while they’re getting established.

Once the spring comes around, you have the option to move your plants outdoors. A lot of growers prefer to wait until the summer, however, since it gives plants more exposure to the sun.

a cabbage growing outdoors
A cabbage growing outdoors – Moving plants outdoors in the summer is something many growers do

Pollination

Just like any other type of plant, vegetables require pollination to grow properly. Growing vegetables in a greenhouse means this can be an issue, since natural pollinators like bees and butterflies won’t be able to get to them.

There are a couple of ways around this problem. Firstly, you can simply pollinate the plants yourself by shaking them. For example, if you’re growing tomatoes, then you can shake the supporting frame gently in order to spread the pollen.

The alternative to shaking your plants is using ladybirds. Having ladybirds in your greenhouse is a great way to pollinate your plants while also bringing some life and character to it.

You can buy young ladybirds online or from certain garden centres. Once you’ve introduced them to your greenhouse, they’ll live for one to two years and will multiply, so you don’t have to purchase more.

Not only are ladybirds excellent for pollinating your plants, but they also help with pest control. They will get rid of problem insects such as aphids, so you don’t need to worry about using pesticides.    

Greenhouse Maintenance

A big part of growing vegetables successfully is taking the right steps to maintain your greenhouse as the weather changes throughout the year. Summer and winter obviously provide very different conditions and as a result, you’ll need to take the right steps to ensure your vegetables are provided with optimal growing conditions.

Below are the greenhouse maintenance steps you should take during summer and winter.

During summer

Although summer is an ideal time for growing vegetables, you still need to ensure you keep on top of your plants if you want them to thrive. Good ventilation is vital during the hot summer months. You can provide this by purchasing a vent kit, or just by keeping the door open.

Another thing that’s incredibly important to do is to make sure that your greenhouse is clean. It’s very easy for dirt to accumulate on the wall and ceiling panels that will stop light from getting through and affect the growth of your plants. This being the case, you should make sure that all the panelling is free of dirt by cleaning it thoroughly.

During winter

Maintaining your greenhouse properly during the winter months is vitally important. If there are holes in your greenhouse that need repairing, then your vegetables could easily be killed by frost damage if you don’t fix them.

In addition to making sure there are no tears or breaks in the structure of your greenhouse, you should also ensure that the temperature doesn’t drop too low, particularly if you’re growing vegetables that aren’t tolerant to the cold. It’s not a bad idea to use a thermostat so you can ensure a reasonable minimum temperature in the greenhouse at night.

The Benefits of Growing Your Own Vegetables

Below are some of the main benefits of growing your own vegetables –

Save money

Growing your own vegetables is a great way to save money, since you won’t have to buy them from a supermarket. The costs involved with growing vegetables is minimal.

You will of course need to buy the seeds initially, but after this there is very little cost involved. You might choose to use fertiliser to help your plants grow, but after you’ve sown the seeds, it’s mostly a case of letting nature take its course.

Better for your health

Another big benefit of growing your own vegetables is that they’re generally going to be better for your health. You can get good quality, organic vegetables in supermarkets these days, but when you grow your own, you know that no pesticides or other types of chemicals have been used on them.

Better tasting

A lot of growers find that their own vegetables taste significantly better than those you’d buy from a supermarket. Of course, the taste and quality of vegetables you can buy does vary a lot depending on where you get them and how they’re grown. That being said – there’s definitely something to the fact that home-grown vegetables taste better.

Sense of accomplishment

Putting aside the practical benefits for a minute – growing your own vegetables comes with a great sense of accomplishment. Watching them grow from tiny seeds to thriving plants that you can feed your family with is a unique experience and buying them from a supermarket just doesn’t compare.

Things to Consider When Buying a Greenhouse

Having a greenhouse is a must if you want to grow your own vegetables. If you don’t have one, then below are some of the main things you need to consider –

Size

Size is always going to be an important consideration when getting a greenhouse. The truth is that you can still grow vegetables successfully, even with a smaller greenhouse, so if you have little space to work with, this shouldn’t be an issue.

Cost

Cost is another important thing to think about. The cost of greenhouses can vary a lot depending on their size, the materials used and where you buy from. If you have a certain type of greenhouse in mind, then you should always shop around to get the best price. Thankfully, the internet makes this very easy to do.

Type of greenhouse

We covered the different types of greenhouses at the beginning of this guide. Although a traditional greenhouse is ideal, if you don’t have the space or simply cannot afford one, then a polytunnel would also work well.

Type of panels

The type of panels a greenhouse has is extremely important as it will determine how much light the plants inside get. Greenhouse panels can be other opaque, semi-opaque or clear. Clear panels will let the most sunlight through and are ideal if you plan to grow vegetables in your greenhouse directly from seed.

Glass is the most obvious type of clear panel, but you can also get polycarbonate panels too.

Opaque panels will still let enough sunlight in for plants to thrive, just not as much as clear panels. Opaque panels can be better for growing plants to maturity in a lot of cases.

If you want a compromise, then semi-opaque panels would be a good choice. You can either cover your greenhouse with semi-opaque panels or use a mixture of clear and opaque panels to get a similar effect. You can have opaque panels on the roof and clear panels on the sides. This way your plants will get a good amount of sunlight as the sun is going down in the evening but won’t be overly exposed during the day.

Insulation

UK winters are typically quite harsh, so good insulation is important. To ensure a greenhouse is well insulated it’s a good idea to use multi-walled polycarbonate panels. This will ensure a stable temperature while still letting a good amount of light in.

Good insulation isn’t just important for keeping the inside of the greenhouse warm, but it can also stand up to high winds. Wind damage is a real risk if you only use a single layer of covering, so it’s always recommended that you use 2-3 layers for full protection.

About the author

Chris Briggs

Chris loves the outdoors and exploring nature. He is a freelance writer and has written extensively on subjects including travel, DIY and gardening.

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