Today, there are tons of greenhouses ready to buy and set up for any taste. Alternatively, you can build one if you want to.
However, for a beginner it is quite confusing which materials to choose, how big the greenhouse should be and where to site it. Or what shape the greenhouse should be?
Don’t worry! I am here to answer all these questions! Here are 14 tips on how to choose a greenhouse in a store or build it yourself.
Step #1. Do you want to buy or build a greenhouse?
If you have a strong DIY spirit and are quite good with the construction I would strongly recommend building a greenhouse yourself.
You can take a look at the “How to build a greenhouse guide” to have an idea of what it takes to build a greenhouse.
Why should I buy a greenhouse?
However, if you are a busy gardener and just want to get the planting going ASAP there are plenty of greenhouse kits on the market.
These usually come in the boxes and you need to set them up but lots of companies offer a service to help you to do that.
A Palram Nature Series Hybrid Hobby Greenhouse is a good first greenhouse buy. I am talking about the pros and cons of this greenhouse model in this review.
Step #2. Space for greenhouse. Assess your property carefully!
It is not only about choosing a territory with a plenty of space so you can buy the largest greenhouse. Instead, try to maximize the available space.
You can do it by getting a lean-to greenhouse (read more in the types of greenhouse structures section). Assess your property carefully.
Make sure that the land is quite flat and is covered from the strong winds. Another thing to consider is the connection to the utilities.
Ask yourself if you are planning on heating a greenhouse? Do you need a watering system?
To help you decide with the answers on these questions please read the next section about the growing goals.
How wide should a greenhouse be?
Most of the hobby greenhouses are 8-10 feet wide but can vary from anything from 12 to 20 feet wide. Most of the commercial options are ranging from 20 to 40 feet wide and up.
Step #3. How much can you grow in a greenhouse?
Decide on your growing goal first. This is probably the most important decision which you have to make before starting growing in a greenhouse.
It determines the type of the structure, its size and materials it is made of resulting in its overall cost.
So, if you are an amateur gardener who is trying to grow something for the first time, go for a mini greenhouse or make a small one yourself from the cheap materials (PVC pipe + polyethylene film).
On the other side, if you are fully committed to the growing in a greenhouse for many years choose the most durable materials.
Also, it does make more sense to get the biggest greenhouse so you won’t need to worry about space when growing different types of plants.
Step #4. Greenhouse Location and Orientation.
Where to site my greenhouse?
The key is to choose the site with the most sunlight which is also covered from the winds. Take into consideration the shadings. It’s better to rely on the special covers rather than trees or nearby constructions.
Don’t put your greenhouse under the trees. WHY?
- The falling leaves can cover the glass and decrease the light transmission;
- The leaves rot and dirt the glazing;
- The shading provokes the growth of green algae;
- The falling branches damage the greenhouse;
- The sticky honeydew secreted by the insects inhabiting the trees can make any greenhouse glazing sticky and dirty which is also very hard to clean up;
- The tree roots can interfere into the beds with plants.
Now, think of the cleaning and repairs. Yes, you will have to do them once in a while! Ideally, allow approximately 2 ft of the nearby space for these reasons.
How much sunlight does my greenhouse need a day?
- 6 hour of sunlight a day for any type of the greenhouse structure
What is the best orientation for a greenhouse?
Now, it is very important to choose the orientation for your greenhouse. You are right by thinking that it should be facing south.
However, the earth is rotating around its orbit. So, the best orientation for a greenhouse is when a structure with the long side of the construction faces east to west and is exposed to the maximum sunlight throughout the day.
Moreover, this accelerates the heating up of the greenhouse after chilled nights. Also, during winter the sun sits lower in the sky.
This means that your greenhouse will get less sunlight than it could in summer, being in the same location.
Step #5. What is the cost of greenhouse?
You need to think what is your budget. Sometimes DIY projects might be more expensive rather than buying a greenhouse kit.
On average, the cost for a greenhouse construction is around 25$ per square foot. Take into considerations your time, cost of the materials and a salary you need to pay workers (if needed).
Alternatively, the starting price for a greenhouse kit is 60$ for around 5 feet wide made of steel frame and PVC cover. A 6 feet wide polycarbonate greenhouse kit with aluminum frame costs around 300$.
Step #6. Greenhouse Installation.
Many of the greenhouse kits come in the box and you need to assemble it yourself. It might take from 5 to 6 hours.
Depending on the complexity of the structure equipment might not be required but you have to always make sure it is clearly stated in the instructions before ordering.
Is it easy to install a greenhouse?
Most of the kits are easy to set up if you organize all of the parts in order of construction and using a socket wrench is sufficient.
We are half way there! Well done!
So, after you decided on the location, space and costs you need to choose the shape of a structure, type of framing material and type of glazing material as well as the size of your greenhouse.
Then I am going to guide you through the environmental controls which can be controlled in a different manner.
Step #7. Find the right type of the greenhouse structure.
The shape of your greenhouse is as important as the material it is made of. I have a list of criteria which help in choosing the right greenhouse structure. These criteria are affordability, running costs, light transmission and how practical it is.
Before we start looking at the different structures you need to know that greenhouse can be attached to an existing building or stand on its own in the garden.
Attached greenhouses are typically found in the lean-to, even-span and uneven-span shapes as they work the best with the building’s wall it is connected to.
What are the Benefits of a Lean-to Attached Greenhouse?
This is probably the most convenient type of the greenhouse. You might ask me why. Okay, imagine that you can walk out of your front door and enter straight into the greenhouse.
Also, being attached to the wall of the house decreases the price of the construction and makes it easier to build it yourself.
Another benefit of the lean-to type is that it is located closer to the water, electricity and heat utilities.
The even-span and uneven-span structures carry the same functionality as attached and freestanding structures. As you already know the attached structure is close to the water and electricity facilities and is cost effective to build.
So, let’s talk about the Freestanding Structures.
Span-Roof or also known as Even-Span Greenhouse Shape
An even-span model is probably the most common structure for a greenhouse. It looks like a small house and is quite easy to build.
Moreover, it is believed to be the most reliable because the snow can come of it easily in comparison to the Gothic arch structure. However, it is debatable.
Snow stays on the greenhouse because the ice is forming on the surface of the greenhouse when the temperature is changing as well as moisture is forming.
So, the ice is forming on a greenhouse of any structure and I would consider it as an advantage to go for an a-frame.
Uneven-span Greenhouse Shape
It is very similar to the even-span type but the rafters are not equal meaning that the space inside will be limited. It is a good option for someone who lives in the hilled area. You can also save some money on building materials.
Gothic Arch Greenhouse Shape
Well, as you probably can tell by the name it is in a form of the arch. In term of the price, these tend to be more popular rather than ‘house’ shaped greenhouses.
Also, Gothic arch structure wins over a-frame in light transmission because vertical sides of the later poor in light transmission and it get through mainly through the roof. The Gothic arch transmits the light through the whole surface of the greenhouse.
A-frame Greenhouse Shape
The A-Frame shape is probably the easiest model to build and the cheapest to buy. To set up this construction you need to install everything in sections from the ground. Then you combine the roof and side walls together to get that triangular or an A shape.
Hoop-house Greenhouse Shape
It is a simple construction with lots of space for plant beds, flower pods station and hanging herbs.
Post-and-Rafter Greenhouse Shape
This is probably the most durable type of the greenhouse which is quite simple to build or to set up.
Cold frame and Hotbed Greenhouse Shapes
These two are the simplest structures often called mini-greenhouse. Both cold frame and hotbed in simple words is a box put on top of the plant beds to keep them warm during the winter. The difference is in the hotbed being heated.
To find more information about the differences in the type of the greenhouse structures, please go to the ‘What are the Different Types of Greenhouse Structures’ article.
Step #8. Choose Greenhouse Frame Material.
It is very important to choose a greenhouse or to build one with a good frame as it provides the support for the whole structure. The most common types of materials for the frame are wood, aluminum, galvanized steel and PVC.
What is the best type of framing material for greenhouse?
If you are a lover of a traditional greenhouse, you have to consider getting a greenhouse with wooden frame. The best types of woods are rot-resistant such as redwood but it might be quite expensive.
Aluminum frame is a good option as it doesn’t rust and lasts long. It can also be painted according to your design.
Galvanized steel is the strongest material for the frame and is really durable because of the hop-dip galvanization. However, it is a quite heavy to work with and it does not retain the heat inside the greenhouse.
The last option is a PVC pipe which is super light and easy to mold, you can easily use it for DIY greenhouse projects. The durability is not that high in a long term but it is definitely the cheapest option of them all. For more details on pros and cons of each frame material go to this article.
Step #9. Choose the framing material in combination with the greenhouse glazing.
I find it easier to think of the frame and glazing as a combo due to the aesthetics and durability reasons.
For example, a heavy glass requires a stable frame made of a durable material like wood which looks aesthetically pleasant as well.
Types of greenhouse glazing materials:
Now the most popular choices are glass or polycarbonate covers. I am going to briefly guide you through the pros and cons of each of the glazing type.
Traditional Glass Glazing Greenhouse
Traditionally, greenhouse is a construction made of wooden frames and a glass as covering material. This option of the glazing for a greenhouse is fairly cheap and easy to set up.
However, it is hard to clean as the dirt accumulates in the joints where the glass panels meet.
Also, the major disadvantage of the traditional glass is in breaking down into large dangerous shards which can hurt people around. That is why many people (including myself) tend to use a safety glass glazing.
Safety Glass Glazing Greenhouse
So, in comparison to a traditional glass which breaks down into dangerous massive sharp pieces of glass an impacted safety glass will break into harmless small pieces.
It is quite easy to clean because it usually comes into long panels. This is a good option for glass lovers but if you are tempted to try out something new then you have to check out a polycarbonate glazing, you won’t regret it!
There are lots of glass treatments to make it stronger. I am going through the pros and cons of each of them in the ‘What is the best glass glazing for a greenhouse’ article.
The plastic materials, such as polythene, which is now widely used to build greenhouse, became very popular. Therefore, the term polyhouse became commonly used between gardeners.
Plastic Film Greenhouse Glazing
There are two types of plastic films used for greenhouses. PVC which stands for polyvinyl chloride and polyethylene.
Plastic film usually last for a season as it degrades under the impact of UV lights, so choose a UV treated option to last at least for 2 seasons.
Here is a good example of the PVC covered greenhouse and this one is a good buy if you prefer a PE cover instead.
Polycarbonate Greenhouse Glazing
Since people started to use polycarbonate sheets for greenhouse the quality of the construction has risen.
Polycarbonate is much cheaper and lighter in comparison to traditional glass.
Also, it does let through a sufficient amount of UV lights needed for the plants and is as durable as glass.
Due to its molecular structure, polycarbonate is a really strong material and doesn’t break as easily as glass.
Moreover, it is heat resistant and does retain the heat in a greenhouse reaching higher temperature (3-4˚C more than in a glass greenhouse).
Again, everything is due to its structure which is double glazed. If you live in the area where late spring or early autumn frosts are a usual thing, polycarbonate covering is for you!
Tip: when buying or building a greenhouse take a look at the thickness of the polycarbonate. The thicker it is the longer it lasts.
If you live in a really hot region, it does make sense to get matte polycarbonate sheets. They scatter UV lights and save plants from burning.
Check out this polycarbonate greenhouse option.
Apart from the polyethylene and polycarbonate glazing there are other options of plastics available on the market.
The range starts from the fiberglass, acrylic and vinyl plastics and finishes with a quite new innovation – Solexx.
This is a good option available on online for an affordable price.
To find more information about the advantages and disadvantage of the different glazing options read the ‘What is the best glazing material for a greenhouse’ article.
Now, when you have decided which construction to get, no matter the shape, the ventilation is a key feature of any greenhouse.
Step #10. Greenhouse Ventilation.
Apart from the fact that a good greenhouse should retain the heat, it also has to maintain a sufficient airflow to release the hot air.
Without proper ventilation the greenhouse can quickly overheat and your plants will die. So, taking into consideration the vents whilst choosing a greenhouse is definitely worth your time.
There MUST BE two essential places for ventilation: roof vents and side vents or louver vents.
The first one allows the hot air out of the top of the construction whilst the second sucks in the cool fresh air.
Also, it is more convenient to get automatic vent opener which opens roof vents gradually as the temperature in the greenhouse warms up.
Step #11. What size greenhouse do I need?
You can find a greenhouse in different widths and lengths. As it was already mentioned before if you want to grow a little amount of your own veg go for small greenhouses like cold frames, hot beds or window mounted options.
What is the best size for a greenhouse?
If you are aiming to grow throughout the year different varieties of plants you need at least a 6ft x 8ft sized greenhouse (6ft wide and 8ft long). This will enable you to organize the shelves inside and hang the plants.
Step #12. Greenhouse Environmental control systems.
Apart from the classification based on the shape of the greenhouse, there are differences in the types due to the environmental controls. In other words, greenhouses can be low, medium and high cost.
Low cost greenhouse
As the names suggests this type doesn’t have any controls.
Medium Cost Greenhouse
This type of the construction carries some extent of environmental control
High Cost Greenhouse
You can probably assume that it is a fully controlled option.
So, what are environmental control systems? These are computer technologies which automatically control the temperature, humidity and light intensity inside the greenhouse. You can adjust them according to your needs.
Step #13. What clarity plastic is the best for a greenhouse?
There are three types of the plastic covers: clear (transparent), translucent and opaque.
Some of the manufacturers make covers with diffusion, semi-diffusion and without diffusion.
As you already know a clear cover lets through full, direct sunlight. This heats up the soil, therefore increases seeds germination and is perfect to grow starters.
The translucent plastic passes some light into the greenhouse and it doesn’t go directly through the plastic. The direction of the sunlight changes multiple times and scatters when is delivered inside the greenhouse.
Opaque plastic distributes the light in different angles to reach the plants. Therefore, the light is spread evenly which is ideal for a balanced foliage growth rather than uneven growing to capture the available light.
Many manufacturers make plastic panels diffused in order to avoid the formation of the hot spots. One of the examples is Solexx.
Another good option is semi-diffusion, usually with the roof being completely transparent and diffused sides of the greenhouse.
Step #14. What color of plastic to choose for greenhouse: green, white or clear?
Sometimes, when you are planning to buy a greenhouse you might find in a description what the cover of the greenhouse is green.
So, why is green plastic used for greenhouses? Is it better that clear? Well, from what I have found a green plastic is used mainly for the aesthetic reasons, to make your garden more attractive.
What does it mean for plants? The green color reflects back the portions of green waves and passes through the rest of the colors. This is not affecting your plants.
Moreover, one of the advantages is that it reduces the light intensity, so your greenhouse will not overheat. Here is an example of the green greenhouse.
Now, let’s talk about the white color. The white cover is in other words an opaque cover which was already discussed in a previous section.
I hope this guide helps you to choose a greenhouse you were always dreaming about! Also, if you have your owns tips on what to check when choosing one please let me know in the comments section below.
Happy growing!
