You know what they say: nothing is ever greater than the sum of its parts... And greenhouses are no exception
For something you want to last as long as possible – while also providing efficient growing conditions, protection, and costs for your growing operation or hobby – thinking about the materials that go into the final product is no joke. At a glance, these structures may seem easy to grasp on a material level. It’s just plastic, metal, and some wood, right? In a sense, yes. But when you get into the details, it’s much more complicated than that.
Inversely to some, they may also seem like enormous and anxiety-inducing building projects to tackle. But don’t let yourself get intimidated that easily! All you have to do, really, is assemble the very best materials to go into your design, and then you have one among just a few simple bases covered for a successful greenhouse. To put it simply: the details of your materials are important to account for, but not all that difficult to grasp... Let’s take a look.
first things first: foundation
Ready to build a greenhouse? Do you have all your ducks in a row with the perfect location and site prep? Then the first material you’ll be working with, obviously, will be your foundation. You have a couple common options: concrete and wood foundations tend to be the ones you’ll see the most. A lot of times too, these foundations will be what the remainder of the greenhouse frame is fastened to for the best support.
A concrete foundation will certainly last you quite a long time if you set it up right, and treat it well. Especially for professional growers, it will really neaten up the appearance of your grow space effectively, and require practically no maintenance over time!
As a huge positive, you’ll have virtually no weeds to worry about with a completely covered floor. Some things to take into consideration though: a drainage system must be installed in the foundation to give water somewhere to go. That is, if you plan to irrigate within your structure – something most people do! Otherwise, standing water on concrete floors can create a problem: eventually wearing away or cracking your concrete foundation, or contributing to excessively moist, disease-ridden conditions for your plants.
You could certainly try the DIY route and apply or pour concrete yourself. But for such a task (especially for a large building), it may be better to hire professional cement mixers or contractors to do this for you – and take note that this will tag on extra costs to your greenhouse setup.
wood foundation (plus baseboards, end walls, and doors)
For the more rustic, “country” feel, consider a wood foundation. A lot of greenhouse owners, especially hobbyists and home growers, tend to lean towards this option, since it’s so simple and easy to implement for smaller systems – not to mention hoop houses as well.
If you want to take a crack at it yourself, this will be much easier (and cheaper) to accomplish than a concrete foundation! On the other hand, you’ll want to choose very rot-resistant, reliable timber and an excellent drainage system within your structure to reduce rot issues. Even then, eventual and routine replacement of the wood will be a very likely reality.
As is the rule for greenhouses in general: avoid chemically- or pressure-treated wood. Chemicals in wood can leach into plants, especially if you are directly growing in the ground. This can harm plants, change the pH of your soil to unhealthy levels, or even get into food crops and be passed on to unwitting customers. Pressure treated wood, on the other hand, may contain elements like copper which are corrosive to any greenhouse parts made of aluminum – so keep wood like that separate during your construction, or avoid using it at all.
Further, you’ll want to be particular about the type of wood you use. Choose rot resistant types well known for their durability and longevity for your construction.
Some good examples are:
- Cedar (Eastern red or western red cedar)
- Black cherry
- Black or honey locust
- Osage orange
- Black walnut
- White Oak
Those who choose wooden foundations often use them as an extended part of baseboard, frame, and door construction, creating a comprehensive and exceptionally stable frame.While wood doesn’t exactly create a “floor” like a concrete foundation would in comparison, builders can combine a wood foundation with a fabric ground cover, gravel covering, or simply leave the earth underneath open for planting.
no foundation – no problem
Do you actually need to have a foundation at all to have a successful greenhouse? Not necessarily! In fact, many don’t use one at all. While a foundation will ultimately lead to a more secure greenhouse that withstands rain, snow, and wind, there are other ways to construct a stable structure with other accessories: such as trussing supports, end walls, anchors and more.
Plus, no foundation – especially the absence of a concrete floor – may be more ideal to a certain line of greenhouse growers, especially those who want to direct seed, transplant, or even use tillers on the ground under their structure. So, as you can see, the true perks of a foundation may depend on what you want to grow, and how you want to go about growing it. In the end, you might not even need (or want) one at all.
Next up, you’ll be taking a look at the materials going into the actual frame (or “skeleton”) of your greenhouse. Many hoop-style greenhouses and high tunnels feature metal hoops or rods to make up the frame over which plastic is stretched as a covering.
However, some permanent greenhouse structures can be framed with plastic pieces themselves, or even wood – much more fitting for a hard plastic or glass covering that need something to fasten to. As you already know, the downfall to wood is eventual rot and replacement. As for plastic (and even PVC, in some models), you can get warping, breaking, - tear from heat and sunlight.
More commonly, you’ll come across much more reliable aluminum frame materials, especially for hoop houses. However, you can also find framing pieces made of tougher, more rust-resistant and long-lasting galvanized steel: heavier pieces to put your structure together, but they’re fail-safe, stable, and completely reliable!
odds and ends: trussing, supports, purlin, and more
Moving on, you’ll also have some reinforcing odds and ends to consider for your greenhouse. Let’s say you have your foundation and frame materials already chosen. You’ll next have to think about the extra bits to lend your building more stability – small additions that, nevertheless, will help your structure go the extra mile.
These may include:
- End Walls
Trussings are long rods installed at the tops and insides of framing ribs for hoop houses and high tunnel greenhouses. They run between each side of your rib arches and join them together, thus making the ribs as standing structures less likely to fall over in wind or rough weather.
It’s best that these are made of a tough metal like aluminum – though galvanized, high gauge steel is even better. Trussings are only one type of support to lend your greenhouse more stability. You can also add small beams, rods, or corners between ribs and your frame or foundation to lend it similar reinforced stability. These can be made of metal or wood of your choice.
Anchors, on the other hand, usually come as the last step after the greenhouse covering has been added. These will help weigh down your entire structure to resist high winds and storms, and may come in the form of cables either tied to weights or staked-down straight into the ground.
End frames and doors are an important aspect to your greenhouse construction. Some basic greenhouse constructions choose wood as a common material, though aluminum or galvanized steel end frames are stronger, longer-lasting options.
Adding the final layer to your greenhouse is truly the icing on the cake. Will you opt for a thin, unrolled length of plastic, or more solid plastic – or even glass? Keep in mind that for tunnels and hoop house structures, a roll of plastic that you can cut, size, and then cover your greenhouse frame with will be the only approach that works.
However, if you are building a square frame, permanent structure with wooden framing pieces, solid plastic and glass can be an excellent choice. It won’t catch in strong winds, and can insulate the plants in your structure more successfully, to an extent.
If you are wanting more moveable structure on a large-rotation farm or growing enterprise, on the other hand, using thin plastic may be much easier. Plus, even after you take down your structure to move it, the same plastic can be rolled up, stored, unrolled, and used again and again in the future.
putting it all together
There are a lot of options for what kind of materials can go into your greenhouse. What you choose will have an impact on the longevity, stability, costs, and even the work you put into constructing it. What you choose to grow will also hold some sway on the exact type of materials and structure that will be best for your plants, too.
So, the next question is: what will you grow, and what will you build? But more importantly: what materials will you put into it? The answer will make a huge difference between the average greenhouse, compared to a greenhouse that will last you a lifetime and more!