How To Choose the Best Glazing For Your Greenhouse?

It’s not just about knowing the best greenhouse glazing systems. There’s a bunch of other factors that you also have to consider before settling on one. If you don’t, you’re going to work backwards trying to grow successfully.
I know the journey there can be daunting, but don’t feel overwhelmed. It doesn’t have to be. Let’s break down your options and figure out the best glazing for your greenhouse.
Why Glazing Matters
We have to talk about why glazing is so important. Yes, it will keep the rain off your plants, but that’s the bare minimum. Glazing will affect light transmission, heat retention, durability, and even your energy bills. It can -and I can’t stress this enough- make or break your greenhouse experience. That’s why you need to take the time to choose wisely because it will pay off in the long run.
Factors to Consider
Light Transmission
Sunlight is the #1 factor to consider when picking a glazing material for your greenhouse. Plants are like solar-powered machines, and they need plenty of light to thrive. Here’s how the different glazing compare:
- Glass: Allows up to 90% of sunlight, and are considered the gold standard
- Polycarbonate: Close second offering about 83-90% light transmission, especially twin-wall varieties
- Fiberglass: Allows 75-85%, but tends to yellow with age
- Polyethylene film: The least effective. It offers about 80-90% initially, but can degrade over time
If you’re growing light-hungry plants or live in a cloudy area, you need to go with glass.
Heat Retention
Your plants will require a stable temperature to stay alive. So if you stay in areas with colder climates, or want to extend your growing season, you need to prioritize this factor in your decision. Some materials are better insulators than others:
- Twin-wall polycarbonate: Excellent insulation
- Fiberglass: Very good heat retention
- Glass: Moderate insulation, suitable for mild climates
- Polyethylene film: Poor insulator unless using double layers
Durability and Longevity
Your greenhouse needs to be able to withstand various weather conditions. You can’t keep replacing the glazing; it’s such a pain to your back and/or wallet.
- Polycarbonate: Incredibly durable and ideal for areas prone to hail
- Glass: Can last decades with proper care but might shatter under certain conditions
- Fiberglass: Moderately durable, but can become brittle and yellow over time
- Polyethylene film: Least durable and needs replacement every few years
If you’re in it for the long haul and don’t mind the upfront cost, durable materials might be worth the investment.
Cost
This is for our tight-budget buddies.
- Polyethylene film: Most affordable option
- Fiberglass: Moderately priced
- Polycarbonate: Higher initial cost, cost-effective in the long run
- Glass: Generally the most expensive
Remember, though, that cheaper materials might need more frequent replacement, so consider the long-term costs too.
Weight and Installation
If you’re a cheapskate and will try to save money on anything, including something as straightforward as installing a greenhouse glazing, then you need to prioritize the weight and ease of installation of the material.
- Polyethylene film: Lightest and easiest to install, no expertise needed
- Polycarbonate: Relatively light and manageable
- Fiberglass: Moderate weight, rigid panels can be tricky to install
- Glass: Heaviest and most challenging to install
Aesthetics
Going into gardening as a hobby or a business, then looks are probably one of the many things that are important to you.
- Glass: Classic, timeless appearance
- Polycarbonate: Modern and sleek
- Fiberglass: Can look a bit industrial
- Polyethylene film: Functional, but not winning any beauty contests
Making Your Decision
Now that you know all the factors you need to consider, how do you actually decide? Start by writing a list of the factors in order of priority. Which ones matter the most to you? Do you care that much about aesthetics? Is gardening a hobby to you so you’re not hell bent on harvesting a ton of produce? Perhaps you’re on a tight budget? Looking to maybe start long term gardening?
Think about all those questions and consider your answers. There, you’ll find a criss cross match and get your final answer.
Wrapping Up
In summary:
- Get yourself a glass glazing if you’re a serious gardener with a decent budget, living in a cloudy climate, and/or care about aesthetics for the gram. A glass glazing will look really good on Instagram.
- Choose polycarbonate if you’re a year-round grower in a variable climate and wants a good balance of light, insulation, and durability. Especially if you don’t mind a modern look and DIY installation.
- Opt for fiberglass if you’re a budget-conscious gardener who still wants decent durability, lives in a mild climate, and is ok with mid insulation.
- Go for polyethylene film if you’re a seasonal gardener, on a tight budget, in a temperate climate, and/or like to change your setup frequently.