Guide To Greenhouse Gardening

Have you ever known a gardener with a home greenhouse and wished you had one, too? If so, you’re not alone.

“Greenhouses are the dream of many gardeners,” says Marc Hachadourian, director of glasshouse horticulture and senior curator of orchids at the New York Botanical Garden. “Usually, only the more advanced take the plunge and invest in a greenhouse for their gardens.”

But, that could be starting to change, says Bootstrap Farmer Katie Russo, who has been seeing a steady rise in sales of greenhouse gardening supplies.

“Greenhouse gardening is becoming more popular among backyard gardeners, hobbyists, and market gardeners as unpredictable weather patterns lead more people to consider the investment,” she says. “Also, more people want to grow their own food and create at-home businesses such as flower farming and niche plant production.”

So is the grass really greener in a greenhouse? If you’re an enthusiastic home gardener curious about greenhouse gardening, read on — we’ve got you covered.

What Is Greenhouse Gardening?

Greenhouse gardening means cultivating vegetables or flowering plants in a controlled, enclosed environment that extends the growing season and protects against pests.

On an industrial scale, fruits, vegetables and grains are grown in huge facilities. There’s even a 60-acre greenhouse in Kentucky that produces millions of tomatoes a year! But for homeowners, it typically involves installing a greenhouse in your garden area.

“I have always found it better to think of a greenhouse as a machine for the growing of plants rather than an architectural structure,” Hachadourian says.

“A greenhouse creates an environment, separate from the external climate, which is regulated and controlled by the gardener to control the growth of the plants within. It’s so much more than a plastic or glass tent to grow plants.” If you’re planning to buy one, don’t forget to check out our collection of the best greenhouse heaters.

Why is greenhouse gardening is smart for serious gardeners?

Greenhouses give you more control over your gardening environment, which in turn gives your plants optimal heat and humidity and reduces the likelihood of pests. They also extend your growing season.

“An unheated greenhouse may buy you a few weeks of extra growing time in fall and spring, and at best, it allows you to grow year-round, even if you’re in a freezing climate,” says Justin Hancock, a horticulturist at Costa Farms. “Want citrus in Minnesota? With a good greenhouse, you can!”

How Does a Greenhouse Work?

Built from plastic, plexiglass or glass, a basic greenhouse turns sunlight into heat while protecting plants from pests, disease and weather extremes. In a greenhouse, the gardener creates the ideal environment for their plants. They can adjust the temperature, control humidity, provide shade as needed and experiment with different soils and fertilizers.

“Depending on the types of plants that you wish to grow,” Hachadourian says, “greenhouses can be used to extend or modify the gardening season, grow edible plants and herbs, start seedlings or transplants for an outdoor garden, overwinter tropical plants, or cultivate a range of plants from climates different than your own.”

Greenhouse gardening also means you can garden on a rainy or even snowy day, and potentially harvest homegrown fruits and vegetables year-round.

“The exacting control of the environment can help grow a huge range of plants beyond what is possible in your climate,” Hachadourian says.

What To Consider When Greenhouse Gardening

Greenhouse gardening is rarely as simple as tossing up a structure and bringing in plants. “In most climates,” says Hachadourian, “a greenhouse will require electricity, water, and heat sources, especially if the plants that you cultivate require heat to survive cold winters.”

Cultivating heat in a glass or plastic room is typically the easy part. The equipment you install determines how you control the environment. Some things to consider:

• Commitment: How committed are you to the year-round chores of greenhouse gardening? One major difference between seasonal and greenhouse gardening, Hachadourian says, “is that Mother Nature is no longer caring for the plants inside a greenhouse — the gardener is now responsible for their watering, care and financial support!”
• Space and permits: How much backyard space can you devote to a greenhouse? Remember, the larger you go, the more equipment you’ll need, from shelving to heaters to watering systems. You may need a local permit to install a greenhouse, especially if it’s a permanent structure.
• Types of plants: “Whether you are growing tropical plants or vegetables,” says Hachadourian, “the greenhouse design and settings will be determined by the type of plants you wish to cultivate.”
• Heat: If you can rely on year-round sunshine to warm your garden, great. Otherwise, you’ll need to install one or more heaters to maintain healthy temperatures for your plants. And unless you’re willing to turn them on and off as needed (and risk forgetting to do either), you’ll need an automated heating system to control the temperature on a set schedule.
• Air circulation: If air can’t move in your greenhouse, your plants will fall victim to excessive heat and disease. That means manually opening and closing windows or vents as necessary, or setting automatic vents on a timer.
• Water and humidity: You’ll need a system for watering your greenhouse plants. That may be as simple as dragging in a hose. Or you may want to install a spigot, irrigation system or even an overhead sprinkler system.

“Always remember that despite the advantages, greenhouses definitely require work and not entirely self-sufficient,” says Hachadourian. “They require investments of time, space and technology for their ultimate success. For those willing to invest, the rewards can be fantastic seeing the plants thrive and grow in ways that they could not without a greenhouse.”

Types of Greenhouses

There are many types of greenhouses, with shapes suited for various plants and designs ranging from simple to involved. They basically boil down to the following options:

• Cold frames and mini greenhouses: These are unheated, good for small spaces and beginners, and help protect plants early and late in the growing season. “They can be made from old windows, EMT conduit, or be as simple as greenhouse plastic encompassing a wire rack,” says Russo.
• Hoop houses: These are essentially a series of hoops covered in plastic sheeting. These are also used for season extension, are generally easy to set up, rely on passive solar heating and are popular with small-scale farmers.
• Traditional glass or polycarbonate: These are permanent structures, often equipped with heating and ventilation systems. “Homeowners often prefer wooden greenhouse structures for a more natural, cottage, or rustic aesthetic, as they can customize them to complement their space,” says Russo.
• High tunnels: These are similar to hoop houses but larger and more permanent. They allow for in-ground planting and usually have space for a wide variety of crops.
• Cat tunnels and low tunnels: These hoop-shaped structures are low to the ground and open up on the ends and sides for ventilation and working. They are a great first step for gardeners who want to add some season extension infrastructure but aren’t ready to take the plunge into full greenhouse growing, says Russo.

Other variations in types of greenhouses include:

• Framing: Most greenhouses are made of lightweight frames that can hold up to normal weather, wear and tear. Frames are typically made of wood, metal or plastic PVC pipe.
• Covering: The insulating material, or what makes up the walls and roof of a greenhouse, is transparent or semi-transparent, usually glass, polycarbonate, acrylic or fiberglass, which comes in a variety of thicknesses.
• Foundation: This should be made of an impermeable material that keeps out water and insects and can anchor the walls. Poured concrete and wood are among the best options. Pre-made greenhouse kits may come with metal floors. For a money-saving option, spread gravel over a porous ground cover that blocks weeds but allows for drainage.
• Shape: Tall, pointed structures like A-frames and Gothics shed snow and work well in northern climes, while round hoop houses are economical and easy to build in more temperate zones, says Russo.

Architecturally, you can also choose between freestanding or attached greenhouses (aka “lean-tos”), which are built off of an existing building, such as your home.

“Traditional freestanding greenhouses offer tons of space for plant variety, but they’re best suited to people with larger yards,” says Manny Barra, a master gardener at TeachMe.To. “Lean-tos are ideal for those with limited space who still want that greenhouse experience.” Lean-to greenhouses can also add extra warmth and insulation to your home.

Portable greenhouses are another option, made with lightweight materials and easy to move, so you can follow the sun wherever it goes. “For the DIY lover, there are also plenty of creative upcycled options, like greenhouses made from recycled windows or plastic bottles,” says Barra.

Professional vs. DIY Greenhouse Installation

Can you build your own greenhouse from scratch? Yes, if you’ve got at least intermediate DIY skills and the right tools. This guide to building a greenhouse walks you step-by-step through the construction of a basic structure.

If you’re less sure of your skills but don’t want to spend a bundle on a professionally built greenhouse, consider a greenhouse kit, available from large home improvement stores. Kits range from simple and inexpensive to elaborate, with prices to match.

If you’re designing a greenhouse or following an existing greenhouse plan, do your homework.

“Doing some research and matching the greenhouse technology and style for the type of plants you wish to grow is crucial for success,” Hachadourian says. “Not all greenhouses are the same. It is best to research and plan to make sure that you build a greenhouse suitable for your budget, climate, and purpose.”

Of course, if you go with professional installation, you’ll presumably work with knowledgeable pros who’ll help you decide on the best greenhouse size and style for your budget. And if something goes wrong, you can always call on them to fix it.

How Much Does It Cost To Install a Greenhouse?

Greenhouse pricing is all over the map — or maybe all over the backyard! Home improvement centers sell small, lightweight, self-assembled greenhouses for less than $100. Prices rise to a few thousand dollars for more substantial models, up to a deluxe kit that sells for more than $16,000.

Pricing for a DIY greenhouse generally runs between $10 and $20 per square foot. That depends on materials, the size of the greenhouse, and fluctuations in the raw materials market.

At Greenhouse Megastore, we found kits priced at about $21 per square foot (for a 6 ft. x 8 ft. polycarbonate greenhouse with no base), $48 per sq. ft. for a 94-sq.-ft. foot model with a galvanized steel base, and even $41,000 for a nearly 300-sq.ft. model. (In case you’re wondering, that comes out to $143 per square foot!)

Professionally installed greenhouses vary greatly as well. It’s safe to assume you’ll spend a minimum of several thousand dollars on a basic model. Are you familiar with sustainable permaculture gardening?

Tools and Materials for Greenhouse Gardening

Your greenhouse gardening tools won’t differ much from those you’d use for standard gardening: pots, hoses, trowels, watering wands, pruners and the like. Unless you’ve got a really big greenhouse, you probably won’t need garden boots or long-handled tools.

“The different ‘tool’ of greenhouse gardening is the greenhouse itself and the type and technology used within to control the environment for the plants,” says Hachadourian.

About the Experts

• Manny Barra is the community garden coordinator for the City of Oakland and a master gardener at TeachMe.To. He is passionate about sustainable gardening, soil health, aquaponics and community food systems.
• Katie Russo is content operations manager at Bootstrap Farmer, a leading greenhouse and farming supply company. A proponent of sustainable farming, she used to work as a full-time greenhouse grower and now manages a native tree farm with her husband.
• Justin Hancock is a horticulturist at Costa Farms, the world’s largest houseplant grower. He has more than 25 years of experience in the horticulture industry as a garden editor, retail garden center operator and plant tag information specialist.