Basic Greenhouse Types and Uses

Freestanding or Attached Greenhouses?

The most basic consideration for your greenhouse is whether you want a greenhouse that is attached or freestanding.

An attached greenhouse simply means that it is connected directly to your home. These include lean-to greenhouses. You can even consider building on a sunroom that will heat up like a greenhouse but can be used for relaxing during winter months. An attached greenhouse can be convenient in that you can make use of the infrastructure of your home to provide electricity and heat. Being close to your house also means that the greenhouse will naturally receive some heat radiating off your home. You just have to make sure that you have a decent south-facing location to take advantage of the winter sunlight. You should investigate also the building restrictions in your community in case you need a permit to construct your greenhouse.

A free standing greenhouse is a completely independent structure from your home. Depending on the size of your yard, they offer the advantage of being as big as you can build them. They also have the advantage of receiving more sunlight than attached greenhouses. However, depending on the kind of gardening you what to do, they can require a greater investment in heating and electricity.

Two Basic Greenhouse Models: Cold Frames and Grow Racks

Coldframes provide the smallest and simplest greenhouse environment and are usually made from polycarbonate panels. They are ideal if you don't have much space. They can be used to give you an early start with tender flowers, herbs, and vegetables. If you sprout seeds indoors, coldframes can also be used to harden the tender plants before they are planted outside.

Coldframes can also be used during winter to protect sensitive plants. When coldframes are not in use, they make great storage containers for your seeds, bulbs, and other gardening supplies. They are generally not intended for growing exotic or delicate plants year round.

Grow Racks are the next size up and can be an attractive addition to your patio or deck. They usually come with a vinyl cover and zippers or Velcro. The zippers or Velcro allow you to adjust the vinyl cover so that you can modify the air flow, temperature, and humidity. Special heat pads can be used under planter boxes to maintain the ideal soil temperature for your plants.

Grow racks can even be an elegant indoor addition for sensitive tropical plants, or for sprouting seeds.

Portable Greenhouses

Portable greenhouses come in a variety of sizes that can range from 6 ft. x 10 ft. to 50 ft. x 100 ft. Some of them use metal frames and cover the frames with heavy-duty polyethylene sheeting.

Of course, the very large portables aren't really that “portable.” However, the smaller portable greenhouses are economical and convenient for homeowners. They often come in greenhouse kits that are easy to assemble and disassemble. They can extend your growing season and enhance the joy of gardening.

Although they are easy to take apart and store during the summer, you may decide that you want to use your portable greenhouse all year round. Be sure that you’ve purchased a portable greenhouse that will stand up to your local weather conditions, especially if you live in an area with extreme temperatures and lots of wind. You can always take your greenhouse down and store it during the most inhospitable months of the year so that it will last longer.

Permanent Greenhouses

Many permanent greenhouses also come in greenhouse kits that do-it-yourself homeowners can put together. They can be more expensive than other kinds of greenhouses, but they are sturdier and more durable. They can take a little longer to put together and may take an extra person or two to get the job done. However, if you are an avid gardener who wants a sturdy greenhouse that provides a range of gardening options, a permanent greenhouse is for you.

Permanent greenhouses come in many sizes and shapes. A large variety of kits are available for both large and small permanent greenhouses. If you want a more substantial greenhouse, you may want to hire a contractor to put it together or build it from scratch.

It is important for you to decide how you will use your permanent greenhouse before you make a purchase. That will ensure that you pick the size and options that are ideal for you. It may be worth while for you to pick the biggest one you can afford because you may enjoy it so much that you run out of space!

Permanent Greenhouse Styles

Except for the Lean-to style, permanent greenhouses can also be referred to as free standing greenhouses. The basic types are described below. As you look at the various styles, remember that you will be happiest if you pick a greenhouse that fits your gardening plans and also looks good in your yard.

Lean-to

Lean-to greenhouses are permanent greenhouses that attach directly to a wall of your home, garage, or other structure. They are usually smaller than other permanent greenhouses. If your lean-to greenhouse is in the right spot, you may be able to provide electricity and plumbing directly through the wall.

Lean-to greenhouses can do as many things as other permanent greenhouses, and are usually more accessible in foul weather.

Classic A-Frame

Classic A-Frame greenhouses have slanted sides. They are strong and can easily handle snow. However, some growing space is lost because of their slanting walls. They are also expensive to heat because of their high ceiling.

Modified A-Frame

Modified A-Frame greenhouses are built with Gable roofs, which are usually not as steep as classical A-Frames. Their shape is similar to what most of us think of as a typical house, except modified A-Frame greenhouses don't have eaves. Their straight walls use space efficiently. Since the roof slope is not as steep as a classic A-frame, the heating bill can be a bit less.

Quonset Hut

Quonset hut greenhouses, sometimes referred to as “hoop style,” are inexpensive and easy to heat. However, their round walls are not necessarily the best use of space. Quonset Huts usually use polyethylene sheeting or sheets of polycarbonate because of their round structure.

Gothic Arch

Gothic Arch greenhouses are similar to the Quonset style, except that the sides are usually straighter and the curved roof is pointed on top. They often have a beautiful shape and are one of the more aesthetically pleasing greenhouse styles.

Barn-Style

Barn-Style greenhouses have perpendicular walls like the modified A-Frame and do not have eaves. They have a Gambrel roof, which creates the barn-like design. Their straight walls make good use of space.

Greenhouse Styles based on temperature

In addition to their design, greenhouses can often be described by the temperature you wish to maintain. Greenhouses can be referred to as cool (“frost-free”), warm, and hot greenhouses (also known as a hothouse), depending on the temperature they maintain and their basic design. While a number of greenhouse designs can serve the purpose of a cool, warm, or hot greenhouse, they may need special equipment to help maintain their temperature.

A cool greenhouse is where temperatures stay around forty degrees F. You can use these greenhouses for seedlings or for storing other plants that won’t need a constant high temperature. For a cool greenhouse, you generally just need the structure and a decent amount of insulation.

A warm greenhouse is a greenhouse where temperatures hover around fifty degrees F. This means that most plants you grow outdoors in your region as tender perennials will survive through the winter in this environment. Some kinds of houseplants do well in warm greenhouses as well. Depending on where you live, you may need special equipment such as lamps as winter months reach their lowest temperatures.

A hot greenhouse is typically used to grow tropical plants and maintains a temperature of 70 degrees or warmer. Hot greenhouses often need special equipment to maintain their temperature such as grow lamps.

Pit and Solar Greenhouses

The basic idea of a pit greenhouse is that you grow your plants at ground level and dig a walkway underground in order to have access to the plants. You can dig the walkway about 3 feet deep and then line it with plywood or another material. This site has a simple description of a pit greenhouse construction and a few nice photographs (look near the middle of the page).

Solar greenhouses are designed to collect and store solar energy to keep your plants warm at night and when the weather is cloudy and colder. They can have a similar design to regular greenhouses and can be either freestanding or attached structures. You can also combine a solar and a pit greenhouse. Free-standing solar greenhouses are more appropriate for growing plants in large quantities and attached structures are appropriate for home use. As with other solar structures, solar greenhouses can either be passive or active.

Passive solar greenhouses are a good choice for the home gardener as they are inexpensive to operate. You can also combine solar energy with other forms of heating to maintain your greenhouse warm during the coldest months. Active solar technology requires more investment and uses solar energy to heat water or air cells where the energy is stored. Photovoltaic heating is also an option can be very expensive.

Check out this site from the National Center for Appropriate Technology on solar greenhouses for more information.