Welcome to Greenhouse 101
Class is in session!
Welcome to Greenhouse 101, your introductory course into greenhouse gardening. We’ll start with a quick history lesson, and explain the principles and mechanics of a greenhouse.
Next, we’ll look at the different types of greenhouses and answer some common questions. Finally, we’ll help you find the right greenhouse for your garden with our buying guide. Let’s get started!
Horticultural History Lesson
The first greenhouses originated in Roman times and were used to cultivate exotic fruits and vegetables imported from around the known world. The Roman Emperor Tiberius was really into cucumbers; greenhouse techniques were developed to keep them on his table all year long. Called “Specularia” for the spectacular things that grew inside of them, greenhouses were only available to the very wealthy.
The idea of subverting nature to grow more plants wasn’t limited to the west. Early greenhouses were also developed in Korea to cultivate veggies in wintertime. The traditional Korean underfloor heating system known as Ondol supplied and maintained heat and humidity inside an enclosed space. Insulated and semi-transparent windows and walls let sunlight in while keeping the cold weather out.
During the Victorian era, greenhouses became more popular and accessible. Commonly used by botanists, herbalists, and gardeners, greenhouses were elaborate decorative structures that graced the grounds of the wealthy and elite. The practice of exerting control over nature by creating artificial environments to grow beautiful and exotic plants had captured the imaginations of the world.
These days, greenhouses are used around the world by commercial food suppliers, nurseries, and florists. They’re also used by backyard gardeners, like you!
How it Works
Greenhouses create an artificial, controlled environment by trapping heat and circulating the warmed air. As sunlight enters the greenhouse through the transparent walls and roof, solar radiation is absorbed by the floor, soil, and plants. The heat is trapped by the enclosed space, causing the internal temperature of the greenhouse to rise. By heating and circulating warm air through the greenhouse, gardeners are able to grow and sustain plants where the outdoor climate is too cold or changes often. Greenhouses also serve to protect plants from wind, rain, snow, and other adverse weather conditions.
By maintaining specific levels of temperature and humidity, a greenhouse can let you extend your growing season for a few weeks, or can create a complete microclimate for year-round growing. Transparent walls are great at letting light in, but they don’t insulate well. Plan ahead on how to heat your greenhouse, if needed; there are electrical, solar, and natural options. Make sure your greenhouse has a ventilation system for air flow circulation and temperature management. Greenhouses generally have two vents; an upper vent that releases warm air, and a lower vent lets cool air in. Vents can be opened and closed as needed.
The ideal location for your greenhouse is on the south side of your house or property. South-facing orientation will give your greenhouse maximum sun throughout the day.
Types of Greenhouses
This traditional style greenhouse features straight walls and a gabled roof. This is the most common greenhouse design, and are usually built with a wood or metal frame and use glass or polycarbonate panels to maximize sunlight.
Pros:
Higher roof for more headroom, maximize space along walls for growing or storage, good air circulation.
Cons:
Difficult to move once built, more expensive to build or buy and maintain.
These greenhouses feature a curved roof and low walls, with frames made of PVC or aluminum pipes and PE plastic panels or sheeting. These are the cheapest and easiest greenhouses to build or assemble.
Pros:
Easy to build, inexpensive, water and snow roll off easily.
Cons:
Not as durable as a traditional freestanding greenhouse.
Similar in construction to the hoop house but with a peak that’s reminiscent of gothic cathedrals, these wide greenhouses are good for growing plants in rows, shelves, and pots. They are good at conserving heat, and their unique architecture make them stand out in your garden space.
Pros:
Simple, efficient, cheap to build or buy, water and snow roll off easily.
Cons:
Lower sidewalls can restrict storage and headroom.
These mini-greenhouses sit flat on the ground and have a sloping lid. They can be placed over raised beds in the garden in spring to warm soil. Easily turn a cold frame into a hot bed by heating it with lights, compost, or your method of choice. Cold frames protect plants from adverse weather and hungry animals.
Pros:
Simple, inexpensive, and easy to use.
Cons:
Can overheat easily, limited space for growing.
A soft-sided greenhouse will be less expensive to buy, build, and maintain. They are lightweight and easier to move if needed. However, they are naturally not as durable. A rounded roof allows snow and rain to roll off easily, but lower sidewalls mean less space for storage and vertical growing.
A hard shell greenhouse will be a sturdy, permanent structure. The sloped roof keeps snow from accumulating. Higher, straight sidewalls and a peaked roof give you more open space for storage and for vertical growing. These greenhouses are more expensive to build or buy and more difficult to move if needed.
A cold frame is the simplest type of greenhouse. Cold frames are essentially bottomless boxes that sit over garden beds or boxes, heating up the soil and allowing you to start cultivating earlier in the spring, or extend your growing season into the fall. If you have limited garden space or an established garden you’d like to get more use out of, cold frames can be a good addition to your space. Easy to use and maintain, these mini-greenhouses are an excellent choice for someone who wants to ease into growing with greenhouses.
Commercial Greenhouse design
Polytunnel greenhouse also called chapel or multi-span greenhouse, is characterized by the shape of its roof, formed by semicircular curved arches and its all-metal structure.
This type of greenhouse would falls into the category of what are commonly referred as multitunel, like Asymmetrical or Tropical and Gothic greenhouses. These type greenhouses are assembled like a Meccano. The different parts stapled together, nuts and bolts, so no soldering needed.
Standard Polytunnel Greenhouse Feature:
Polytunnel Greenhouse Advantage:
- High structural durability and resistance to corrosion;
- More operation space & utilizable area;
- Good ventilation and temperature adjustment;
- Easy installation & maintain;
- Economical input with faster output;
Gothic greenhouse differs from chapel greenhouse, in the design of the arches, these are pointed, They can accommodate a larger volume of air, providing better microclimate and interior lighting.
It is designed to suit all types of crops, particularly suspended crops and the construction is intended for extreme climates.
Gothic greenhouse differs from chapel greenhouse, in the design of the arches, these are pointed, They can accommodate a larger volume of air, providing better microclimate and interior lighting.
It is designed to suit all types of crops, particularly suspended crops and the construction is intended for extreme climates.
Gothic Greenhouses For Professionals
These gothic arch greenhouses provide a traditional appearance and superior functionality. They have been used with success on numerous types of growing operations, and since the internal environment can be controlled, they’re an ideal option for growers in any region seeking a cost-effective growing structure that can improve crop quality.
Gothic Greenhouse Advantage Includes:
• A high-quality, yet economical, option for professional growers and operations.
• Ultra-durable frame ensures a long life. The 1.66” OD frame is constructed from 14-gauage, triple-galvanized steel.
• Gothic arch greenhouses are covered with a dependable double layer film that allows growers to control the growing environment. The top layer is made from Sun Master® 6 mil, 4 year Greenhouse Film. The inner layer is made from Sun Master® Infrared Anti-Condensate Thermal Film. This film provides excellent drip control, which supports healthier plants and ensures maximum heat retention.
• Gothic Pro Greenhouses allow growers to quickly and effectively ventilate the structures. Roll-Up Sides utilize a “Twist-of-the-Wrist” Assembly that enables growers to lower and raise the sides without help.
• The end walls are clad with 8 mm twin-wall polycarbonate, which provides strength, improved insulation. Polycarbonate comes with a 10 year warranty.
• Each greenhouse comes with at 48”W x 92”H entry door that is constructed from heavy-duty aluminum and polycarbonate panels.
• Comes complete with heavy-duty ground posts.
• Customers can choose to save hundreds on equipment by outfitting Gothic Pro Greenhouses with GrowSpan Systems. Systems support environmental control and include a heater, circulation fan, intake shutters, exhaust fan with shutters and thermostat.
These greenhouses models are named Tropical greenhouses because their use is widespread in this region, and also asymmetric, because, unlike the Gothic and chapel greenhouses, its geometry is asymmetric, with one side of the roof steeper than the other.
The slope of the roof is studied as a function of perpendicular incidence on this of sunlight during the winter, in order to maximize the incoming solar radiation
the greenhouse ventilation is usually not fixed and is determined through the openings located in the center of each structural arches which run along the entire ceiling. The openings allow natural ventilation and heating vent.
Sawtooth Greenhouse is used more often in tropical areas. The structures combine optimal ventilation with special strength for withstanding different loads.
In addition to the side ventilation, the greenhouse is supplied with a permanent ventilation opening on top, provides 25% of the total ventilation of the covered area. At the same time, it can be covered with insect net. When open the sawtooth vent allows a continuous airflow to reduce the inside temperature or can be closed to optimize the climate control of the growing area.
The shape of the arches allows excellent light transmission. Various standard widths and wall heights focuses on flexibility and the practical use of growing space and conditions.
Advantages:
• Make possible utilize the light in winter
• High thermal inertia due to their high unit volume
• Waterproof to rain and air.
• Good ventilation due to its high altitude.
• Allows installation of roof ventilation downwind.
• Strong winds resistance.
• It is fast to assemble and needs no welding.
Experiencing high demand and good results thanks to the vast volumes and excellent ventilation offered by this model, mitigating the effects of high temperatures and humidity in cultivation, thus obtaining optimal development.
Based on the design of the greenhouse structure, this one is different due to its 4-metre modulation and has roof-top ventilation that allows continuous and greater air renewal inside the greenhouse and the incorporation of balconies on the sides to minimize the “edge effect” and strengthen the structure, thus obtaining a light, strong and reliable structure.
The structure of the Arin greenhouse can be used for both projects with and without crop loads. Greenhouses without crop loads are considered to be those dedicated to crops that do not require support from the structure (flowers, leafy vegetables, baby leaf, etc.).
If an installation with crop loads is required (tomato, pepper, cucumber, etc.), the grating is added to suspend the crop and the sides with braces.
For the covering, the most usual option in these cases is to use plastic for the roof and mesh in the perimeter such that the crop is protected and a high rate of air renewal is allowed. In some cases roll-up plastic has been installed over the mesh of the perimeter.
Tunnel greenhouses don’t have straight walls, the structure is completely curved from the point of attachment on the ground to the ridge. The shape of the arcs may be curved or arched.
It is composed of one or more modules with a series of arches made of galvanized cylindrical tubes, which do not require concrete footings, enabling transfer and easy installation. Its shaped allows accommodating a larger volume of air inside and provides resistance to rain.
Advantages
• Cheap and simple greenhouse
• Better climate control.
• Allows the installation of air conditioning systems.
• Increased sealing capacity.
• Good deal of light inside the greenhouse.
• Reduces condensations and dripping water problems on crops thanks to the curved roof, which allows the evacuation of the water from condensation on the plastic cover.
• Zenith and side windows installation.
• Facilitates agricultural machinery operations.
• Fast to assemble and needs no welding.
Tunnels are tall greenhouses similar in construction to the low plastic tunnels that vegetable growers often construct over a row of tomatoes or other vegetables to give them a head start in the spring. This concept was expanded to use on a larger scale so vegetables could be grown in high volumes and maintained in the tunnel using large scale equipment. High tunnels are typically tall enough for a tractor to work in.
Tunnels are typically unheated and ventilated without power equipment. The sun light heats the interior much higher than the outside temperature creating exceptional plant growth on the inside. Ventilation is typically done by opening then ends and rolling up the sides.
The main differences between a greenhouse and a tunnel are that in a greenhouse, plants are usually grown in pots on a table while a tunnel has the plants growing right in the ground as they would in a garden. Greenhouses are typically designed to use heaters and powered ventilation systems or evaporative coolers. Tunnels typically do not have heating systems or cooling systems.
The purpose of our tunnels is to reduce the risk of lost crops from heavy rain and to also start the plants growing earlier in the spring giving us an earlier harvest.
In the fall of 2009 we set up tunnel #1. In the spring of 2010 we planted it with strawberries, red raspberries, yellow raspberries, black raspberries, purple raspberries, and a few of the primocane fruiting (fall bearing) blackberries.
Berries do not produce in their first year and they do not require very much space in the first couple months after planting, so we planted veggies in between all the rows of new berry plants. The vegetables were harvested and removed by mid summer so the berry plants had space to continue to grow.
Whether you’re a professional farmer looking to extend your growing season and improve your annual output, or simply a backyard gardener looking to take your veggies to the next level, a protected growing space can really make a difference – but when it comes to making the right choice, you’ve got options.
Generally, today’s farmers interested in choosing from the wide variety of protected growing spaces available have three main options to choose from: high tunnels, greenhouses, and hoop houses. Choosing the right one for your farm or garden, however, may require a bit more of an in-depth understanding of where they differ, and how each can bring its own unique benefits.
Here’s a closer look at all three of these popular covered growing spaces, as well as a few pointers on how to select the option that works best for your budget, your needs, and your desired results.
While often confused for a traditional greenhouse, high tunnels actually represent a relatively new development in the world of protected farming and gardening—complete with unique benefits and limitations that should be taken into account before getting yours up and running.
Although similar to a standard greenhouse, high tunnels are uniquely designed to be lighter, more mobile, more flexible, and more versatile than their larger, more permanent cousins. This gives high tunnel growers unique advantages when it comes to building a growing area ideal for vegetables and leafy greens, among other crops.
- There’s A Reason They’re Called “high Tunnels”
While it may seem obvious, the main difference between a “high tunnel” and a traditional greenhouse is really right there in the name—high tunnels are often taller, with higher ground posts than a standard greenhouse.
Originally, this change was made to accommodate one specific need: the ability to bring tractors, tillers, and other tall farm machinery directly into the growing space itself. Because many of the standard sizes of traditional greenhouses are not tall enough to drive a tractor directly inside, high tunnels were developed to give growers that much extra headspace to fit in the big machines.
Early high tunnels really functioned primarily as spaces where large machines were required. However, it did not take long for farmers and gardeners around the world to recognize that this new design provided other, significant benefits that standard greenhouses had thus far been lacking.
With only a single layer of covering, high tunnels offered the perfect option for growers looking to combine outdoor and indoor growing throughout the season. With crops planted directly in the ground under the high tunnel (as opposed to in raised beds, as in a greenhouse), farmers have the option to simply remove the poly covering and give crops in a high tunnel full exposure to the outdoors. Then, when the weather starts to change, the covering can be replaced for nearly full protection.This flexibility offers the perfect growing environment for season extension, protecting crops from the worst of the early spring frost and the late fall chill without the burden of a fully-equipped greenhouse system.
- Designed For Easy Installation
High tunnels are specifically designed to minimize installation time, often “sacrificing” the durability and overall strength of a standard greenhouse for the immediate benefits of this simpler design.
Typically utilizing just a single layer of poly covering (rather than the multi-layer poly used on a traditional greenhouse), roll-up side curtains, and often no electricity or environmental controls, high tunnels maximize efficiency without needing to leave room for extensive additions or specializations.
And, because they do not require a traditional foundation, high tunnels can be installed significantly faster and easier than a standard greenhouse.
- Movable And Adjustable For Superior Control
Thanks to a lightweight design and a minimalist, “unplugged” setup, the average high tunnel also provides one major benefit that traditional greenhouses struggle to match: moveability.
Our Rolling Thunder movable high tunnel system, for instance, combines all the unique benefits of a high tunnel with nearly unmatched mobility. By mounting a relatively lightweight high tunnel system on top of a wheel/ground post rail system, Rolling Thunder allows growers to transfer their high tunnel coverage across a long stretch of terrain. This allows for more precise control over the growing process. - Plenty Of Options To Expand & Excel
Even though a high tunnel is specifically designed to be flexible, that does not mean it can’t fulfill the duties a farmer or gardener might expect from the average greenhouse system.
Although designed to function as a simple covered growing space with the option to remove the poly covering for full outdoor exposure, high tunnels can still be outfitted with environmental controls, ventilation, and even electricity. While not standard to the high tunnel design, these additions can turn even a simple high tunnel into a powerful growing tool for farmers and gardeners of all sizes.
Greenhouses: Superior Strength & Durability for Year-Round Growing
Tough, durable, and able to withstand even the worst of what the winter can throw at it, a true traditional greenhouse is a grow space designed for full-year operation—providing protection that often exceeds that offered by a high tunnel or hoop house.
Greenhouses typically include a more robust system of coverings, more durable ground posts, and stronger support systems to keep the growing area protected beyond what is possible in a high tunnel.
Together, these improvements boost a greenhouse’s ability to extend the growing season, pushing beyond simply extending the spring and fall growing seasons to actually supporting full, year-round farming. Free from insects and removed from troublesome soil diseases, greenhouse growing can represent a significant “insurance policy” against many of the common problems experienced by outdoor farmers and gardeners.
Additionally, by growing crops within a durable, protected greenhouse – bolstered by wind load and snow protection—farmers can proceed through all four seasons confidently knowing that the protected grow space can handle the coldest colds and hottest hots, from the depths of a winter blizzard to the middle of a crushing summer heatwave.
Often utilizing environmental control systems like heating, ventilation, humidity control, and supplemental lighting, greenhouses are the ideal choice for farmers, growers, and gardeners looking to maintain productivity from season to season without interruption.
As with any fully-enclosed indoor growing space, factors like heat, humidity, and light can quickly become problematic—sometimes even inviting common diseases into the greenhouse, which can spread within the controlled environment extremely quickly.
This is why many greenhouse systems are designed to seamlessly incorporate environmental controls to prevent the worst of these issues, helping to keep the climate within your greenhouse at the ideal spot for your crops without losing the protective benefits of the covered growing space.
Hoop Houses: A Smaller, More Nimble High Tunnel
Often associated with backyard gardens and small-scale farms, hoop houses are actually simply a smaller sized high tunnel designed to maximize simplicity while preserving so many of the benefits offered by a high tunnel or greenhouse.
Utilizing simple, curved purlins with poly covering stretched over the top, hoop houses do not require durable foundations, extensive environmental controls, or complicated arrangements.
Ideal for constructing by yourself or with a small team, hoop houses can be installed quickly over an existing crop bed or above a planned crop area to provide season-extending protection within a growing space no larger than a backyard garden plot.
By adding a few hoop houses together, a farmer or gardener can create a specialized covered growing area ideal for protecting leafy greens and other crops from early spring or late autumn frosts.
Because a hoop house offers semi-permanent protection over a regular outdoor grow area, they can be the perfect solution for small- to medium-size operations looking for basic protection from wind, sun, rain, and snow. And because the simple poly covering can help prevent the worst of what the wind can bring, your crops can stay protected from summer storms and autumn gusts well beyond what would be achievable on an uncovered plot of land.
Protect Your Crops Under The Choice That’s Right For You
Whether you opt for the durable protection of a traditional greenhouse, the flexibility of a high tunnel, or the simple but effective covering of a hoop house, these covered growing options can make a great addition to any farm or garden focused on extending the growing season.
If you’re ready to get started on your next greenhouse, high tunnel, or hoop house—or if you need further assistance in deciding which is right for you—we’re here to help. Get in touch with our expert greenhouse sales team and we can help get you set up with the option best suited for year-round success.
Why use a Greenhouse? Do I Need One?
If you love gardening, get a greenhouse! Our Out sunny Greenhouse Kits are affordable and easy to assemble, so there’s no reason not to take the plunge if you’ve been on the fence about greenhouse gardening.
So Which Greenhouse is Right for Me?
How much space do you have? What do you want to grow? How much time do you want to spend maintaining the greenhouse and plants? These are all important questions to ask yourself before committing to a greenhouse kit.
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