Step 1: Know What Type of Garden You Currently Have, and Would Like to Have

• What types of plants do you currently cultivate? What types of plants would you like to cultivate?
• What types of environments are most beneficial to the plants you would like to grow?
• How much space do you need to comfortably house your plant collection?
• 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.

Step 2: Know Your Environment

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 will be casting longer shadows, potentially blocking 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 and structures in the environment block sunlight, they may also block high winds. It will be beneficial to determine how best to place your greenhouse so that high winds can be blocked while still allowing a maximum amount of sunlight.

Drainage: You will want to place 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 reside in a climate prone to heavy precipitation.

Accessibility: It is important to consider the proximity of the greenhouse 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 garden may need the most attention.

Building Permit: It may be necessary to obtain a building permit for your greenhouse. Check local ordinances to determine whether this applies to you.

Step 3: Know Your Options

It can be difficult to navigate the seemingly endless amount of features available for greenhouses. Choosing the proper greenhouse size, shape, and determining the best materials and accessories for your needs will all help optimize your gardening environment.

Keeping in mind steps 1 and 2, use the following information to learn more about greenhouse features, and which features will work best for you.

• Greenhouse size: As a general rule, it is a good idea to plan on purchasing a greenhouse slightly larger than what you think you may need to allow for plant collection growth. Similarly, if you plan to further develop your gardening skills and expand your garden in the future, you may want to consider this interest when deciding which size greenhouse to purchase. If you plan to utilize the greenhouse for commercial, educational or institutional purposes, it may be beneficial to 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 size option 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 easily accessible from the home. It also costs much less to heat and power a lean-to greenhouse, as 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 problematic for your growing garden. Free-standing greenhouses are, likewise, independent structures. Environmental factors must be taken into careful consideration prior to choosing your greenhouse’s location. See Step 2 for additional considerations.
• Greenhouse materials: One of the most overwhelming aspects of choosing a greenhouse is deciding among the seemingly endless amount of materials available. 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 5 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.

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 more effectively diffuse light into the greenhouse, decreasing sun damage and minimizing shadow. Polycarbonate is also generally a very effective insulator, especially in double- and triple-layered forms, which dramatically reduces energy costs to heat and cool 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 popular 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 or box greenhouses, as it is lightweight, portable, and easily transmits light and retains heat for small environments.

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. 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

It is nearly impossible to give your plants exactly what they need as often as they need it without some kind of assistance. To optimize growth in the greenhouse environment, accessories are often needed and utilized to regulate temperature, control humidity, provide water, accelerate growth, and organize plants.