Building Your Greenhouse

(Dec 21, 2007)

1. What is a Greenhouse?

A greenhouse is a small house-shaped structure made of glass or plastic. It is designed to maintain optimum temperature and moisture inside it to help grow a wider variety of plants than the local climate will normally support and to protect them from any extreme weather. Certain gases in the atmosphere, like carbon dioxide, water vapor, methane and nitrous oxide do not allow heat to escape back into the atmosphere. This quality makes these gases popular in commercial greenhouses. All greenhouses function on the same principle; they store heat from the sun. The glass or plastic panels of greenhouse reduce the amount of heat escaping while allowing light to penetrate. This increases the temperature within the greenhouse and keeps your plants warmer in winter. Greenhouses range from a small structure for keeping in your terrace garden to as big as a city building. Their glass panels are grouped according to their transmission rate. The energy trapped within greenhouses heats up both soil and plants. They prevent or reduce infrared radiation, convection of gases and arrest electromagnetic radiation too. Greenhouses are used for growing vegetables, fruits, flowers, and even crops like tobacco. You can grow flowers and vegetables in late winter in greenhouses, then transplant them outside in early spring. These houses have meant an increase in artificial pollination although using bees is preferred when practical. You have to maintain specific levels of humidity and heat within your greenhouses and control any potential influx of pests and associated diseases. You can irrigate the plants in greenhouses if the need arises. The increased temperature is essential if you try growing summer vegetables in winter. Greenhouses maybe used to protect plants from blizzards and dust storms too. Such greenhouse cultivation proves useful in deserts, Arctic wastelands and other land areas with poor fertility. 

2. Uses of a Greenhouse

A greenhouse helps you grow your plants at regulated temperatures and humidity levels. It is easier to regulate temperatures within small greenhouses. Greenhouses are not necessarily hot houses. They allow the required amount of heat to be present within so that plants do not suffer from extreme heat or extreme cold. Having a greenhouse need not be a luxury. With a little persistence and innovation, you can have a greenhouse anywhere.  

The Main Uses of a Greenhouse are

• Helping small and tender plants to grow from seeds earlier than usual

• Grow plants within indoor environment in winter months

• Helps carry forward garden plants to use as stock in the next season

• Increases the variety of plants and blooms

• Allows you to experiment with new varieties of flowering plants and vegetables too

• Helps cultivation of winter vegetables in pots

• Helps maintain a continuous supply of vegetables all year through

• Helps develop your hobby of growing plants even if there is a space crunch 

3. Steps for Building Your Greenhouse:

1) Erect the six feet pieces within a distance of four feet in marked area. Allow protrusion of 48” from the ground.

2) Use the fence staples to nail a 2 x 6 runner on rebar stakes.

3) Put twenty-foot rebar stakes on PVC pipes. You may need another person to hold one end while you do the other end. All drilled holes should be on a line parallel to the ground.

4) Slide PVC pipes over rebar stakes, making sure there are no sharp ends or rough pipes.

5) Carefully slide wire through all PVC holes and along the eight PVC pipes forming the roof.

6) You also have to wire together the four-foot PVC pipe lengths with copper or baling wire. Wrapped wire can force PVC pipe inward.

7) Use vertical 4x4 foot posts to construct end walls. Check that your end walls are vertically straight.

8) The door should be tight to prevent wind from entering the greenhouse possibly causing problems.

9) Fix nails on the horizontal posts and push them into the ground.

10) With help from others, slide the plastic over the cage and secure the ends by nailing it. Your greenhouse is ready for setting up the internal climate. Then, you can add any of your own innovations. 

4. Greenhouse Types and Styles

There are many different styles and types of greenhouses. Some of the more popular are:

A Freestanding Greenhouse: This greenhouse has an independent structure, not attached to your home. It has independent sidewalls, end walls and a gable roof. You can make it in any size, shape and style that you like and that can get planning permission for. The amount of sunlight penetrating your greenhouse depends on various factors in its construction. You could an need extra heating system if the free-standing greenhouse is completely separate from a heated building. This freestyle greenhouse spreads over seventeen to eighteen feet. It can accommodate two walks, two side benches, and a center bench.  

An Attached Greenhouse: These greenhouses are connected directly to your main building. Such greenhouses receive heat radiated from your home. Additionally, you can arrange for any necessary heat and light infrastructure from your home too. Also, be sure to take into consideration any special building restrictions that exist before constructing an attached greenhouse. There are different types of attached greenhouses, including lean-to, even-span or window-mounted.  

Permanent Greenhouses: These greenhouses are the most expensive greenhouses. They are more durable and can withstand extreme temperatures and weather conditions. Enthusiastic gardeners can assemble a permanent greenhouse to suit their individual needs and preferences in many shapes and sizes from a number of self-assembly kits that are available. Some of the most popular styles include:

• Lean-to - leaning on to the main building

• Classic A-frame with slanting sides

• Modified A-Frame with gable roofs and straight walls

• Quonset Hut with round walls and hoop style

• Gothic Arch with straight sides and curved roof pointed on top, and

• Barn-Style greenhouses. 

Portable Greenhouses: These greenhouses are available in many different sizes ranging from six feet to fifty feet in length and ten to a hundred feet in width. The largest of these are still often called portable even though they are not portable in the true sense of the term. Some of these use polythene sheeting and many have metal frames. There are various portable greenhouse kits available. You can assemble and re-assemble them to fit changed circumstances. These portable greenhouses help you enjoy your hobby of gardening at any place and throughout the year. When you purchase a portable greenhouse, check if it can withstand the most extreme temperatures and other weather conditions you can expect to experience in your area.