Glass greenhouses are not only beautiful and timeless, they also let in the maximum amount of natural light, which is crucial for plant photosynthesis. But with so many options on the market, it can be hard to know where to start your search.
First, glass greenhouses come in all kinds of different sizes, shapes, and styles to fit your preferred aesthetic. More importantly, however, you’ll want to pay close attention to the following features: glass type, insulation value, and frame durability. Depending on whether you live in a colder climate and want to garden through the winter months or live in a milder climate and want a greenhouse for year-round gardening, different materials will suit your needs better than others.
As experts in all things greenhouses, we’ve created this guide to help you understand not only when a glass greenhouse is the best option for you, but also what features are right for your needs and climate. To make things even easier for you, we’ve determined the overall best glass greenhouse kits that we know you’ll love.
What are the advantages of a glass greenhouse design?
One of the most important aspects of a greenhouse is its ability to transmit light to the plants inside. In this area, glass greenhouses are superior to polycarbonate greenhouses; due to the clarity of glass, nearly 100% of natural light is transmitted (89-91%)! This better light transmission is particularly useful if your greenhouse is partially shaded during the day or if you plan to grow in the winter months when the days are shorter and there isn’t much light to be transmitted in the first place.
Compared to polycarbonate, greenhouse glass (also known as horticultural glass) is more durable and does not scratch easily, meaning that it will retain its clear appearance for years to come. When properly installed, high-quality glass glazing can last a lifetime.
As far as sustainability goes, glass is made from silica, a non-toxic, natural resource. This means it is less likely to cause pollution if left in the environment. However, it is worth mentioning that glass does have a larger initial carbon footprint than materials such as aluminum, mainly because of the high temperatures needed to melt down silica.
What are the disadvantages of a glass greenhouse design?
One of the biggest disadvantages of a glass greenhouse is the cost: new glass panes cost more upfront than polycarbonate greenhouse glazing, there’s simply no way around it. On the flip side, polycarbonate panels have to be replaced more often due to the inevitable discoloration and deterioration over time, which could make glass more economical in the long run.
Additionally, glass is quite heavy, making for a more difficult installation process as well as increased shipping costs.
Although a glass-paneled greenhouse is quite the investment, its durability and aesthetic value are factors that make it an excellent choice.
A note on shipping glass panels
Although glass is tough, it is not unbreakable, and proper precautions need to be taken by the supplier when shipping glass panels for your greenhouse. In most cases, glass panels are shipped firmly inside wooden crates or on pallets to prevent movement and sudden breakage. When your greenhouse arrives, it’s important to check all glass panels for any signs of cracks or breakage so you can communicate any mishaps and request replacement panels if needed.
Because glass is much heavier than plastic, the cost of shipping will likely be higher, which is something to bear in mind when purchasing a glass greenhouse.
What glass type is the best choice for a greenhouse?
Choosing between polycarbonate and glass is not the only choice you have to make when it comes to greenhouse glazing. There are a few different types of glass that are used in greenhouse design, and it’s important to be familiar with the key differences so you can pick the right glass type for your environment and aesthetic preferences.
There are three main types of horticultural glass: annealed glass, tempered glass, and laminated glass. We’ll go over these three types of glass, as well as whether it’s better to get single or double glass for insulation purposes.
Annealed glass (aka “standard glass” or “float glass”)
Don’t be deterred by the name; annealed glass is just a fancy term for ordinary glass, which can also be referred to as “float glass.” During manufacturing, annealed glass is cooled slowly to relieve internal stress, resulting in glass that is durable and resistant to breakage.
If it breaks, however, it does so in large shards that can be dangerous. As a result, we don’t recommend annealed glass for high-impact or load-bearing areas of the greenhouse, including the roof, door, or windows. However, it may be used for the walls of a greenhouse with relatively little risk, allowing you to save costs.
Tempered glass (aka “safety glass” or “toughened glass”)
Tempered glass is annealed glass that has been heat-treated for extra durability. Essentially, the glass undergoes rapid heating and rapid cooling, resulting in tension up to four times stronger than regular annealed glass.
Also commonly referred to as “safety glass,” tempered glass is designed to shatter into many small, harmless pieces when it breaks. As a result, tempered glass is the preferred choice for glass greenhouse kits. However, one downside is that it is more expensive than annealed glass.
Laminated glass
Lastly, a less common option for greenhouses is laminated glass. Unlike either annealed or tempered glass, laminated glass stays in place even if it breaks. That’s because it is made of two sheets of glass bonded together with a polymer interlayer. In the case of breakage, the polymer layer holds the glass together. In fact, your car windshield is made of laminated glass.
Laminated glass is an excellent option for greenhouses and should not be overlooked. If rocks, hail, or even a tree branch were to hit a pane of laminated glass, it would break without shattering, thereby keeping your greenhouse protected from the elements until you’re able to replace the panel.
If you need tinted glass to reduce heat, laminated glass might be what you’re looking for as well. Tint or no tint; insulation and UV protection are additional benefits of laminated glass.
Single-pane glass vs. double-pane glass
Once you’ve decided between annealed, tempered, and laminated glass, there’s one more thing to consider: getting single- or double-pane glass. There are advantages and disadvantages to both.
First, let’s talk about insulation. Insulation is commonly measured by something known as R-value, which is essentially how much resistance a material has to heat flow. A higher R-value means more resistance, which is equal to higher insulation.
The R-value of most single-pane glass is around 0.95, compared to an R-value of 2 for double-pane glass. What this means is that double-pane glass is better at insulation. But that does not necessarily mean that you have to get double-pane glass for your greenhouse.
Let’s take a closer look at the differences between the two:
Single-pane glass
As evidenced by the R-value, single-pane glass has a relatively low insulation value, lower even than most polycarbonate greenhouses. However, it is less expensive than double-pane glass, has better light transmission, and has a crystal clear appearance.
If aesthetics are your primary focus, single-pane glass may be the right choice for you. Additionally, your greenhouse may not need more if you live in a mild or warm climate, where single-pane glass might actually be better at preventing your greenhouse from overheating in the summer months.
Double-pane glass
With a higher R-value, double-pane glass offers superior insulation to single-pane glass. This makes it a good choice for those trying to grow in cold climates. Additionally, the added insulation is crucial if you’re planning on providing supplemental heat or cooling in your greenhouse, as it will prevent unnecessary heat loss.
On the flip side, double-pane glass is more expensive, and it transmits slightly less natural light. However, lower light transmission is rarely an issue for greenhouse-grown plants. climates.
Best Glass Greenhouses – Our Top Picks
If you’re ready to purchase the glass greenhouse kit of your dreams, you should pick one with the highest quality. You want a greenhouse with a sturdy frame and glazing that provides the right level of insulation for your climate. While there are many good options out there, we’ve determined the best greenhouses available on the market today:
Best overall glass greenhouse kit: Livingten Insulated Glass Greenhouse
For the average greenhouse gardener, a greenhouse kit is the way to go. Not only is it typically cheaper to buy a greenhouse kit than to DIY one, but they often come with a warranty in case of malfunction.
That said, our favorite overall glass greenhouse kit is the Livingten Insulated Glass Greenhouse. It is built to withstand any type of bad weather and the 22-mm double-pane glass panels with an R-value of 2.3 ensure that your plants stay warm even when temperatures outside drop. Plus, this greenhouse design is breathtaking, making it more than just a space for your plants; it’s a first-class quality greenhouse environment fit for entertaining and relaxing! There are three different models to choose from, ranging from 11ft x 14ft to 11ft x 20ft in size.
Features of the Livingten Insulated Glass Greenhouse include:
- A full-length LED light bar for ambient light
- “Cold-wall” barriers within the aluminum frame for extra insulation
- 22mm double-pane glass panels (4mm glass, 16mm air pocket, 4mm glass)
- Two double sliding doors, one in the gable end and one in the sidewall
- Four roof vents with automatic openers
- Two pop-out side windows
- Three sets of roll-up shade curtains
- Rainwater gutter system
- R-value: 2.3
- 20-year warranty
Runner-up for best glass greenhouse kit: Janssens Royal Victorian Greenhouse
Another glass greenhouse kit we often recommend to our customers is the Janssens Royal Victorian Greenhouse. While this greenhouse features less insulation (the R-value with glass is 1.2), it is a beautiful, classic English greenhouse that should not be overlooked.
The strong aluminum frame is elegant yet durable, and the glass windows paired with the steep roof truly make it look like the classic Victorian glass greenhouses we’re familiar with. Built to last and endure harsh conditions such as high winds, this greenhouse is the perfect place for all of your growing needs. The base greenhouse kit comes with a single door, but hinged double doors can be added at an additional cost. There are four different sizes to choose from.
Features of the Janssens Royal Victorian greenhouse include:
- Thick, strong aluminum frame
- 4mm tempered glass sidewalls
- Rubber seals between the frame and glazing for added insulation
- R-value: 1.2 (glass)
- 6in high foundation frame
- Louvered windows with clear Lexan covers for winter (number of windows depends on size of the greenhouse)
- Single or double sliding doors depending on size of the greenhouse
- Rain gutters with downspouts
- Roof ridge decor
- Misting system
- 15-year limited warranty
- Optional with Premium Kit: Full-length narrow top shelf, inside shade cloths (full length with pull ribbons), long seed tray
- Optional reinforcement kit to further increase stability for extreme winds and high psf snow loads
Best custom glass greenhouses: BC greenhouses
If neither of the above glass greenhouse kits are right for you, it’s possible that you may be better off with a custom greenhouse to better suit your needs! In that case, we highly recommend choosing BC greenhouses; they have over 4,000 greenhouse models to choose from – all of which are built to last with high-quality materials.
Some of the things you can customize include:
- Size, shape, color, and design of the greenhouse
- Type of glazing
- Attached vs. unattached
- Number of doors, windows, and roof vents
- Made in the USA
- Additional features such as fans, misting systems, and more
