How to Build a Greenhouse
Six Parts:Choosing a LocationChoosing a StructureChoosing Covering MaterialsConstructing the
FrameControlling TemperatureAdditional Greenhouse Planning
A greenhouse is a structure that produces a microclimate ideal for plant growth. It
can be used to start plants or house them throughout their life. Building a
greenhouse is a large project to tackle; however, it can be done on a budget or by
Part 1 of 6: Choosing a Location
Choose a south facing area. The main element required for a greenhouse is good
All structures should be to the north of the greenhouse.
One of the main greenhouse structures is a lean-to. Choosing a south wall of a
building is a good option.
Give preferences to locations that have morning sun over afternoon
sun.Although all-day sun is the best option, opening up the area to morning light will
increase the growth of the plants.
If there are trees or bushes near the greenhouse location, ensure they do not give a
shadow until late afternoon.
Pay attention to winter versus summer sun. If the area to the east is open and
sunny, it will get more sun November through February. 
Winter sun has a lower angle, so trees, houses and other structures are more likely
to pose a problem.
Do not choose a location near evergreen trees. Deciduous trees lose their leaves
and will not shade the location in the winter, when the greenhouse requires more
Choose a location that has access to electricity. Most greenhouses require some
heat and ventilation to keep the temperature optimal.
If you build a lean-to, you may be able to extend power from the house.
A separate building may require hiring an electrician.
Pick a well-drained area. You will need to syphon away excess rainwater.
If your location is uneven, you may need to fill in the area to encourage drainage.
You may be able to use cisterns to catch rainwater falling from the eaves of your
greenhouse. Any conservation of water and electricity will help keep greenhouse
Part 2 of 6: Choosing a Structure
Measure your location. Whether you build the greenhouse from scratch or build it
with a kit, you should choose the size carefully.
The larger the greenhouse, the more money it will cost to build and heat.
The most popular greenhouse size is 8 by 6 feet (2.4 by 1.8 m).
Choose a greenhouse kit, if you have little experience building or few people
to help you erect the greenhouse.
You can get a pop-up or polycarbonate greenhouse from home improvement stores
and Amazon for as little as $150.
Larger, sturdier models range from $500 to $5,000 depending upon size.
Look at websites like Costco.com, Home Depot, or Greenhouses.com.
Make a lean-to. If you have chosen an area against a building, you may as well
construct a simple lean-structure that uses the remaining wall as support.
If you have a brick structure, the heat from the building can help you keep a steady,
This is a fairly easy structure to make yourself. You can support it with rebar,
wooden beams and fewer supports that an offset building.
Build a Quonset frame. This is a domed ceiling that can be made with steel
supports or PVC tubing.
The domed shape means there is less head and storage space that rectangular
This shape can be built with little cost; however, the less expensive the material, the
less sturdy it is likely to be.
Pick a rigid frame. With this design, you will need a foundation and a frame. Unless
you are a designer, you will want to buy a plan for a greenhouse or employ someone
to build it.
A rigid frame, post and rafter or A-frame greenhouse will need a foundation and a
You will need the help of friends or employees to help you build a large framed
Part 3 of 6: Choosing Covering Materials
Use UV stabilized polyethylene. The light transmission is similar to glass, although
it is light and inexpensive.
Plastic film has to be replaced every few years.
It must be washed occasionally.
It will not hold heat as well as glass, but is adequate for lean-tos, Quonsets and
small stand-alone framed greenhouses.
Use hard, double-walled plastic.
Polycarbonate can be curved slightly around the frame and it has an energy savings
of up to 30 percent, because it is double-walled.
80 percent of light filters through.
Buy fiberglass. If you are building a framed greenhouse, you can save money by
choosing fiberglass over glass.
Choose clear fiberglass.
It will need a new coat of resin every 10 to 15 years.
Invest in higher-grade fiberglass. Light transmission is greatly reduced on low-grade
Choose glass. This is the most attractive material, if you are building a greenhouse
that will accentuate your house or garden.
Glass is very fragile and is expensive to replace.
You must build a framed greenhouse with a foundation.
Tempered glass is preferable because it is stronger than regular glass.
If you are going to the expense of installing a glass greenhouse, you should consider
bids from construction companies to ensure the foundation and frame can handle the
Part 4 of 6: Constructing the Frame
Use strings along the ground to measure where you want the supports to be
set. Pound stakes in the ground
Reinforce with rebar. If you are building a lean-to or Quonset, you can reinforce
your frame with rebar and PVC.
Pound rebar into the ground every 4 feet (1.2 m). Leave 48 inches (121.9 cm)
protruding from the ground.
Once the rebar is set, you can loop 20-foot sections of PVC to create your frame.
Stretch your plastic film over the frame and attach it to beams at the bottom.
Pour gravel on the ground in an even layer, after your supports are driven into
the ground. Small, loose gravel allows for extra drainage in a greenhouse
Hire builders to pour concrete, if you need a foundation. They will need to bring in
concrete forms and pour the floor of your greenhouse before it can be framed.
Treat any wood you use before using it.
Untreated wood can degrade in as little as 3 years.
Choose your wood treatment carefully. Some wood treatments require that the food
is no longer listed as “organic,” because of the use of chemicals.
Consider a treatment like Erdalith, which has limited leaching properties.
Use metal supports in place of wood supports whenever possible.
Seal the covering to the frame as closely as you can. You may be able to simply
bolt film to wood.
The more expensive the covering, such as glass, fiberglass, or double walled plastic,
the more time you should take to seal it to the foundation and frame.
Research the best procedure for the covering of your choice.
Part 5 of 6: Controlling Temperature
Place fans in the corners of the greenhouse. Set up fans so that they are
They should run almost constantly during the winter months, to ensure the entire
greenhouse is benefiting from the heater.
Install vents in the ceiling of your greenhouse. They can also be located near the
top of the supports.
Some ventilation of carbon dioxide is essential.
The vents should be adjustable. You will need to open them wider in the summer
Consider installing an electric heater. Solar heat may only account for 25 percent
of the heat in your greenhouse, so a backup heater is essential.
You can also use a wood or oil-based heater, but it must be vented to the outside to
ensure good air quality.
You should check with your town or council to see what heating options are available
in your area.
Install a forced-air system, if you are using a glass-frame greenhouse. If you
can afford to outfit your greenhouse with its own temperature control system, then
you can set it up to grow almost anything.
Employ an electrician and a contractor to install your system.
It may need regular maintenance to ensure it can handle ventilation and heating in
Install thermometers or thermostats. You should install several thermometers in
case 1 breaks.
Place them at different levels of the greenhouse so that you can observe the
temperature in your greenhouse at all times.
You can buy a thermometer that measures the temperature inside your house and
inside your greenhouse, so that you can watch it closely during the winter months.
Part 6 of 6: Additional Greenhouse Planning
Study planting conditions for the plants you want to grow. The more sensitive
the plant is to changes in heat, the less likely you will be able to grow other plants in
the same section.
A cool house is a greenhouse designed to keep plants from freezing. It is ideal for
A hot house is a greenhouse designed to keep plants in tropical temperatures.
You will need to choose what the temperature will be and keep it steady. It is not
possible to create different zones in an open greenhouse.
Ensure you have a steady water supply. Ideally it should be supplied by hose
water and cisterns.
Construct raised beds inside your greenhouse. Slatted tables can be used in the
meantime, since they will allow water to drain through the table and into the gravel.
If possible, construct the beds to the primary gardener’s height to limit ergonomic
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