If you don’t have one, you might wonder if you should be using a greenhouse. It is said that every vegetable gardener needs a greenhouse. But is this true?
Greenhouses have been used since the 17th century, so it would seem that they are a useful tool for any gardener. Because they have a variety of benefits, every keen vegetable gardener will sooner or later wonder if they need one. If you are one of them, wonder no more, we have the answer.
In this article, we will explain what greenhouses do and why we think that every vegetable gardener should be using a greenhouse.
What Does A Greenhouse Do?
Let’s start with the basics and have a closer look at the uses of a greenhouse. After all, how can you know if you should have one, if you don’t know what benefits it will bring you.
A greenhouse is a structure that consists of a metal or wood frame and glass or polycarbonate panels.
During the day, the sunlight shines through the panels and warms up the air inside. This air is then locked inside, so that it stays warm, even if the temperatures outside sink.
This provides your plants with two things. First, a warmer temperature that will help them to grow and, second, the sunlight they need to photosynthesise, i.e. produce food for themselves.
Generally, we differentiate between an unheated and a heated greenhouse.
Unheated Greenhouse
An unheated greenhouse only uses the power of the sun to provide warmth. This means, it will lose its heat overnight and when the sun is not shining.
As a result, they are also called cold greenhouses.
There are things that can be done to increase the heat retention in unheated greenhouses, without adding a heater.
By adding materials with a higher density, you can ensure that more heat is stored during the day and released overnight. These materials include water, brick or stone.
For example, you could build a low brick wall on which the greenhouse will sit. The bricks will warm up during the day and then slowly release the warmth when the temperatures sink.
Equally, a stone floor will have the same effect.
You could also put water tanks in your greenhouse, which will perform the same service as the bricks or stones.
However, even without the additional heat stores, these cold greenhouses still have a lot of benefits for vegetable gardeners. We will get to these a bit later though.
Heated Greenhouse
In contrast, a heated greenhouse has an artificial heat source, such as an electric heater. Ideally, on a thermostat, to keep the greenhouse at a constant temperature.
As a result, a heated greenhouse can be used all year round to create the perfect conditions for the plants you want to grow.
Now let’s have a look how you could be using a greenhouse to grow the vegetables you want more successfully.
The Benefits Of Using A Greenhouse For Vegetable Gardeners
As we have said, the purpose of a greenhouse is to create the right conditions for your plants. And by doing this, you can:
- extend your growing season – potentially grow fruit and vegetables all year round
- overwinter tender plants
- grow exotic plants that might not otherwise grow in the weather conditions of the UK – even tropical plants
- grow your vegetables from seed without having to fill up your sunny windowsills
- hardening plants to get them used to being outside
With a greenhouse you could be self-sufficient for your fruit and veg, as you could have homegrown produce all year round. If this isn’t a reason to be using a greenhouse, I don’t know what is, right?
Plants that are commonly grown in greenhouses are tomatoes, chillies, aubergines, cucumbers, courgettes, lemons, oranges, etc.
There will be different benefits to an unheated and heated greenhouse.
Benefits From An Unheated Greenhouse
If you decide to have a cold greenhouse, you can still use it to extend your growing season. You will be able to plant out your vegetables earlier, and they will be able to produce a crop for longer.
And a lot of summer crops, such as tomatoes and chillies, will benefit from being in an unheated greenhouse and provide a bigger yield.
If you have plants that are a bit tender, as in, they need some shelter from the worst of the British winter, then a cold greenhouse is great. You can even provide extra protection by covering the plants with horticultural fleece.
Hardening plants works like a treat in an unheated greenhouse. Because while the plants can get used to the outside climate, they are still protected from the worst weather.
If you are considering using a greenhouse, an unheated greenhouse has definitely a lot going for it.
Benefits From A Heated Greenhouse
If you add artificial heating to your greenhouse, there are a wide range of benefits. Apart from everything you can do with the unheated version, you can also grow fruit and vegetables all year round.
Because in the colder months, where the sun might not be as strong, your greenhouse will still be the right temperature for your plants.
You can also create the right growing conditions for plants that would never grow in our climate, even during summer. Using a greenhouse allows you to even grow tropical plants. Just look at the greenhouses in Kew Gardens, where they have a host of different climates and grow plants from all over the world.
With a heated greenhouse, you basically eliminate the seasons. Yes, in winter the days are shorter and therefore there is less sunlight, but your plants will still get enough to grow and produce crops.
What Is Important When Choosing A Greenhouse?
The decision to be using a greenhouse is only the first step, because then you have to choose the right greenhouse for you.
To make this choice easier, we have put together a little guide on how to choose a greenhouse.
1. What Do You Want To Use It For?
As we have seen above, a greenhouse has a lot of benefits and uses. Depending on what you want to use it for, your choice will be different.
Do you want to become self-sufficient and grow enough fruit and vegetables all year round to cater for your family? In that case, you will need a heated greenhouse of an adequate size.
If you want to prolong your growing season, but only plan to grow a few plants, a cold frame might suffice. These are much smaller than greenhouses and are not suitable to provide a frost fee environment all year. But they can still protect your plants from the cold weather, as long as it isn’t too cold.
Do you want to overwinter your tender plants, then a mini greenhouse might be enough.
Do you want to grow exotic plants, then you will need a heated greenhouse that can provide the right climate for these plants.
2. What Is Your Budget?
The budget is probably one of the most important considerations. You can get greenhouses for every budget, but the smaller the budget, the more basic greenhouse you can get.
And this is fine, as long as it is still fit for the purpose you want to use it.
The cheapest greenhouses will have an aluminium frame, ideally galvanised to make it rust-resistant. And polycarbonate panels, which are cheaper than glass. While the plastic panels won’t let as much light through as glass, it won’t break and is better at insulating the greenhouse. So, definitely a good option if you are on a budget.
If you can afford it, you might want to invest in a glass greenhouse, as it will look a bit nicer and let more sunlight through.
The most expensive greenhouses will have a cedar wood frame and toughened glass panels. These are seen as the best greenhouses, because they are safer and the wood will store heat and release it slowly. They will also need a lot of maintenance though.
And if you have a big budget, you can also look at greenhouses with special features, such as automatic ventilation, where the windows are opened automatically when the greenhouse reaches a certain temperature.
Or an integrated heating system, that will keep the greenhouse at the same temperature all year round.
If you want to provide extra heat storage, you can have a greenhouse that is half-walled. This is great for heat retention, but it does mean you can’t grow any plants on the ground.
Some greenhouses also come with a rainwater collection system, making it easy to water your plants in the greenhouse. Or it might come with an integrated potting bench where you can work on seeds or cuttings.
And size will also play a role in the price. The bigger the greenhouse, the more expensive it will be. We would recommend that you buy the biggest greenhouse that you can afford, to ensure you have the space to do what you want.
You should also take into account the installation and ground preparation. If you are not confident in putting up the greenhouse yourself, you will have to pay to get it installed. And you need to lay foundations before you can put it up. These additional costs need to be taken into account when deciding on your budget.
No matter the budget, there are some things that every greenhouse should have.
3. The Must-Haves For Every Greenhouse
If you are using a greenhouse, you should make sure it has some form of ventilation. Whether this is a door that can be left open, windows that can be opened or a roof vent.
This is important because you want to ensure that there is good air circulation in your greenhouse to keep your plants healthy. Warm, damp conditions could increase the risk of fungal diseases.
Of course, depending on the types of plants you want to grow, these might be the conditions you are after.
But ventilation is not only good for air circulation. Roof vents or windows can also help to cool down the greenhouse in summer. In hot weather, the temperature in a greenhouse will soar and this could damage your plants.
Automatic vents would be best, as these will open either at set times or when the greenhouse reaches a certain temperature. However, this will increase the costs.
So manual roof vents or windows and doors that can be opened are fine. Just remember to use them in hot weather.
Another must-have is shading. While you want your plants to get as much sunlight as possible, in the height of summer, it could get too much for some plants.
One way of providing shade is by having blinds that can be closed. You can also paint your panels, but blinds are more flexible.
4. Choose The Right Type
You can generally differentiate between freestanding greenhouses and lean-tos.
Freestanding ones need more space, as they are normally wider. They are designed so that the sun is let in on every side.
A lean to, is built onto a wall, which means it is narrower. This makes it great for smaller spaces.
While a lean to is more difficult to ventilate, it is much better at heat retention. Because the wall it is attached to will lock in the heat for longer and release it slowly.
Lean-to greenhouses are especially useful if they are mounted on a south-facing wall.
You do also have greenhouses that have more unusual shapes, such as dome or octagonal shape. These might look nice, and they are also easier to fit in weird spaces.
If you make sure you keep these things in mind, you will find the greenhouse for you. But you might want the benefits of using a greenhouse, but your budget is tighter, so you can’t afford the size you want. Well, there are alternatives.
Alternatives To Using A Greenhouse
If you would like to be using a greenhouse, but your budget is tight, or you don’t have space, don’t worry, there are alternatives.
Polytunnel
The most suitable alternative to a greenhouse is a polytunnel. This is a metal structure with a plastic sheet over it.
Both fulfil the same purpose, but there are differences. The main one is price. You can buy a good size polytunnel for much less than the same size greenhouse.
If you have the space, but not the budget, then a polytunnel might be the way for you to go.
A polytunnel can be used in the same way as a greenhouse, so you can prolong your growing season or grow more exotic plants.
You can get big walk-in polytunnels or smaller ones to cover your beds.
Cold Frame Or Mini Greenhouse
Another alternative is a cold frame or a mini greenhouse, as we have already mentioned above. A cold frame is a box with a glass lid. Sometimes the whole box is made of glass.
A mini greenhouse is also a box, but is normally higher and opens from the side. It can be made out of glass. But you can also get ones that have an aluminium frame and a plastic sheet. These are much cheaper, but still very useful.
Most gardeners use a cold frame or mini greenhouse with a greenhouse, but if you lack space or money, a cold frame or mini greenhouse can be a good alternative.
You can use both to harden off plants before you plant them out. But they also work well for growing summer crops such as tomatoes or aubergines.
As they provide shelter from the elements and additional warmth. Tomatoes or chillies in a cold frame or mini greenhouse will ripen faster than when grown outside.
Overwintering plants can also be done in a mini greenhouse or cold frames. However, you will want to add extra insulation to ensure your plants are safe from frost and draught.
As you have seen, every gardener should be using a greenhouse as it provides so many advantages. However, there are also alternatives available, if a greenhouse is just not an option for you.
