Read through our informational buying guide to help you decide which type of greenhouse is best for your gardening needs.

What types of plants do you currently grow? What types of plants would you like to grow?

What types of environments are required to the plants you would like to grow? Do you only need minimal protection for overwintering dormant plants, do you want to grow salad greens year-around, or do you want to grow tropical plants?

How much space do you need to comfortably grow your plant selections? TIP: Be sure to plan for the future. Greenhouses and water features are the two garden projects that are ALWAYS built too small the first time!

Do you see yourself devoting more time and energy into growing more plants? If so, you may want to think about a greenhouse that allows some extra space, or that is easily expandable. Consider your own comfort if you will be spending a lot of time in your greenhouse: Many lower cost greenhouses have very little headroom, or working room.

Step 2: What type of building site do you have to work with?

Take some time to become fully aware of the environment surrounding the potential greenhouse site. This will help you determine the best possible location for your greenhouse.

• Sunlight: Generally, the greenhouse should be located where it will get the most sunlight. Proximity to deciduous trees, while potentially increasing the amount of shade, is also a desirable option. Deciduous trees may help provide necessary shade during the warmer months of the year, but are bare during colder months, allowing more sunlight. Also, keep in mind that the angle of the sun is much lower during winter months, and that any objects in the environment such as fences or neighboring houses will be casting longer shadows, potentially blocking winter sunlight from your greenhouse.
• Weather: High winds and adverse weather, especially during extreme temperature lows (and highs), can negatively impact your greenhouse and plants. Although trees, fences and buildings in the environment block sunlight, they may also block high winds. Try to determine how to situate your greenhouse so that high winds can be blocked while still allowing a maximum amount of sunlight.
• Drainage: Build your greenhouse higher than the surrounding ground so that precipitation and ground water will drain away from the greenhouse. This is especially important if you live in a climate prone to heavy precipitation. Consider using a loose gravel floor in your greenhouse.
• Accessibility: Try to build your greenhouse close to sources of heat, water, and electricity. Additionally, the greenhouse should be easily accessible for you, especially during periods of adverse weather and/or extreme temperatures, when your greenhouse crops may need the most attention.
• Building Permit: It may be necessary to obtain a building permit for your greenhouse, especially if you plan on building a shed or lean-to type that is attached to an existing building. Check local ordinances to determine whether this applies to you.

Step 3: Research your greenhouse options

It can be difficult to choose from the seemingly endless amount of features available for greenhouses. Choosing the proper greenhouse size, shape, and determining the best materials and accessories as they relate to your specific needs will all help optimize your indoor gardening experience and success.

Use your results from steps 1 and 2 to learn more about available greenhouse features, and which features will work best for you.

• Greenhouse size: It is a good idea to plan on purchasing a greenhouse slightly larger than what you think you may need to allow you to expand. A word to the wise: Build the largest that your site and budget can handle!  Have you ever seen a home gardener’s greenhouse that wasn’t stuffed to the rafters?  Similarly, if you plan to further develop your gardening skills and spend a lot of time inside the greenhouse in the future, you may want to consider your own comfort when deciding which size greenhouse to purchase. If you plan to utilize the greenhouse for commercial, educational or institutional purposes, you should consider a larger greenhouse designed for such use. If you plan to build a lean-to greenhouse, its dimensions must coincide with the existing structure. If greenhouse portability is a must for you, a more compact and easy to move or disassemble size may be best.
• Greenhouse type: The two most common types of greenhouses are free-standing and lean-to. It is important to consider the features of each type before deciding which is right for you. Lean-to greenhouses share a wall with an existing structure, usually a home. This type of greenhouse is usually easily accessible from the adjoining building and can cost much less to heat since it shares a wall with another structure and power source. However, as it may be considered an extension of the home, it may be necessary to obtain a building permit for your lean-to greenhouse. It is also important to consider that sharing a wall with an existing structure reduces sun exposure, which may be a problem for your particular greenhouse site. Free-standing greenhouses are independent structures. Environmental factors, especially sun and wind exposure, must be taken into careful consideration prior to choosing your greenhouse’s location. See Step 2 for additional considerations.
• Greenhouse materials: There are seemingly endless amount of materials available, but the choices become simpler once you determine what seasons and growing conditions your greenhouse is going to be used for and what your budget is. The materials of your greenhouse will determine how much light reaches your plants, how well your greenhouse is insulated, how much maintenance is required, and your greenhouse's longevity.

PANELING MATERIALS

• Polyethylene: The most common material used by commercial growers, polyethylene is lightweight, inexpensive, and effectively transmits light into the greenhouse. Easily installed and energy efficient, polyethylene usually has a lifespan of 2 to 6 years before needing replacement. Polyethylene sheets used for greenhouses are typically coated with a UV-resistant layer to protect both the polyethylene and the plants from UV damage. Commercial growers often use two layers of poly with a small squirrel-cage fan maintaining a slight positive air pressure between them. This affords some insulation and helps the snow to slide off easier in the winter.
• Polycarbonate: A relatively new and inexpensive material used for greenhouse coverings, polycarbonate is a durable, impact-resistant, and virtually unbreakable form of plastic. In single-layer form, polycarbonate has transparency comparable to glass, with high light transmission. Double- and triple-layer forms of polycarbonate generally have structural walls between layers for added strength and durability. Double- and triple-layered polycarbonate panels effectively diffuse light into the greenhouse, decreasing sun damage and minimizing shadow. Polycarbonate is also a very effective insulator, especially in double- and triple-layered forms, and can dramatically reduce the costs of heating and cooling your greenhouse during periods of extreme temperatures.
• Glass: The traditional greenhouse covering, glass is aesthetically pleasing and provides optimum visibility of plants. Glass has a high degree of permanence, is very heavy, and requires a very strong frame for support and durability. Glass that has been tempered is necessary for safety in greenhouse construction, as it is much stronger than regular glass. Glass is likely the most long-lasting greenhouse material available, forming a strong, air-tight structure that withstands high winds. Generally, multiple-layered glass is more impact-resistant, a better insulator, and durable than single-layered glass, making it more energy efficient and less prone to breakage. To increase the energy efficiency of a glass greenhouse, interior plastic insulation can be used to retain greenhouse interior temperatures; also, polycarbonate roof paneling is sometimes used in glass greenhouses, as polycarbonate has greater insulating capabilities and diffuses sunlight more effectively than glass.
• Acrylic: Similar to polycarbonate, acrylic is a strong, durable plastic with high light filtration. Its visibility is comparable to glass, making it a lightweight, inexpensive alternative to the often cumbersome and breakable option of glass. Acrylic greenhouse panels are typically accompanied by polycarbonate roof paneling, as polycarbonate has greater insulating capabilities and diffuses sunlight more effectively than acrylic.
• Polyvinyl Chloride (PVC): A form of plastic, PVC is typically used for compact cold frames or small portable greenhouses, as it is lightweight, portable, and easily transmits light and retains heat for small environments. It has a short lifespan.

FRAME MATERIALS

• Aluminum: Aluminum is one of the strongest and most durable frame materials available. Slightly more expensive than other materials, aluminum requires very little to no maintenance and will not deteriorate as a result of prolonged sun exposure and precipitation. Because aluminum is metal, however, it is a good conductor of heat and cold, making it more difficult to regulate temperature in the greenhouse's interior.
• Galvanized Steel: Steel is widely recognized to be the strongest structural material available for a greenhouse frame. Heavier than aluminum, most commercial growers prefer galvanized steel because of its low cost and durability. Also, because less steel is needed to create a strong frame as compared with other materials, less shadow is cast into the greenhouse, ensuring greater sun exposure. Steel's finish will eventually rust and wear from prolonged humidity.
• Wood: Strong and long-lasting, wood is favorable because of its beauty and energy efficiency. It is easy to mount hooks and other greenhouse accessories to a wood frame. However, wood will deteriorate over time due to exposure to dampness, humidity, and insects. Redwood and cedar are normally recommended as woods that are more resistant to wear and tear. Chemical sealants are also recommended for wood frames to prolong the life of the wood, which may be a problem for organic growers. Additionally, wood frames take up more space and are heavier than an equivalent metal frame, which increases shadow inside the greenhouse.
• Plastics: Various heavy-duty plastics are commonly used for greenhouse frames, including polyvinyl chloride (PVC) and resin. Plastic structures have become increasingly popular because they are both inexpensive and portable, and are less complicated to install than metal structures. While not as strong as metal and more prone to sun damage, plastic frames are more energy efficient than metal frames.

GREENHOUSE ACCESSORIES

Fans, vents, heaters, wiring, plumbing, benches, thermostats, shade cloth and many other accessories come into play with the more advanced and permanent greenhouse, and they all combine to help you enjoy your greenhouse gardening experience. For the beginners who are unsure of their needs, there are many high quality complete kits that offer quality components, often at reduced prices compared to buying them separately.