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Cooperative Extension Service |
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Agricultural
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Arbor Day
Dale Bumpers College
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Hobby GreenhousesDecisions • Materials • Sunlight • Options • Pest Control
Before you jump it, decide if you really want or need a greenhouse. How much space do you need? What are you planning on growing, and how much time do you have to maintain it? Do you simply need space to overwinter tropical plants, or do you plan on actually growing in it? Hobby greenhouses used to be small glass houses or fiberglass buildings. Today the choices in coverings run the gamut from glass, tempered glass, fiberglass, polycarbonates, and plastic. In the polycarbonate family there are numerous choices from corrugated, to double-layered, and various grades in that. Simple plastic coverings are the least expensive to install, but will have to be replaced in three to four years. Fiberglass is next. The polycarbonates come next but vary on the grade and make, with pricetags to match. Glass is usually the high end, with tempered glass 25% more than regular glass. Materials for the structure are not just the covering. The frame can be made of wood, steel, aluminum or even plastic pipe. The form can be anything from an a-frame to a Quonset, with all shapes in between. A simple greenhouse can be made by using a chain-link fence top rail, bend it and cover with plastic. This could be used for starting early vegetable transplants, overwintering houseplants, or simple uses. Do you want a stand_alone structure, or a room addition to your house? Before you make all of these choices, visit others who have greenhouses. Find out what worked well and what didn't. The more sunlight you have, the more flexibility you have in what you can grow. But you will have to work on temperature controls, more. Even in the winter, greenhouses in full sun can get pretty warm. Ventilation is a key component to greenhouse success. In Arkansas, cooling a greenhouse will be more critical than heating a greenhouse. Automation is the way to go, unless you never plan to leave your greenhouse alone. Basic options in cooling are to either reduce the amount of light coming in during the summer or venting. Many greenhouses use both -- they have vents and they use a shade cloth for cover. Some newer operations actually allow for the sides to be raised for extra ventilation. You can have vents on the top, or on the sides, or both. Exhaust fans also help a great deal. Evaporate cooling systems work well. In evaporative cooling, they use corrugated cardboard or synthetic fiber pads. Water circulates to the top and cascades down the pads. Air is pulled through the pads, and as water evaporates, it absorbs heat and therefore cools the air. The closer to the pad, the cooler you are. If the greenhouse is small and shaded, a small air conditioner can be used for summer -- but you would need to turn off the vent system while using the it. Heating with natural gas is the most efficient, with propane as another alternative. Small units could use electric heat, but it is expensive. A relatively new system uses hot water through pipes in the floor. Heating is usually required November through March, but be sure not to keep it too warm during the day. A good thermostat is a wise investment. Cost of heating is directly related to the size of the greenhouse. People often ask about using wood burning units, but they become impractical with labor needs. Once the structure is in place, there are lots of options for benches, lights, mist propagation chambers, bottom heating units, potting areas, sinks and computer control systems. You can use drip irrigation, hoses or misters. The more money you want to spend, the more you can, but you don't have to have all the bells and whistles. Benches can be as simple as a couple of cinder blocks with boards across the top, lath structures or state of the art aluminum frames. Floor coverings can be plastic (which is extremely slippery), landscape fabric, gravel or concrete. You can add to the greenhouse as time goes by, and as you see what your needs are. Now that you've built your greenhouse, start growing. You may want to start herbs or flowers, vegetable transplants or get into the propagation of houseplants. You may have a hobby of growing orchids, and your whole house is devoted to orchids, or bromeliads or cactus. The sky is the limit. Pest control is an important consideration also. Sanitation is really the key. Keeping the greenhouse clean will make your job a lot easier. If you have a disease or insect infested plant, remove it from the greenhouse, before it infests everything. Monitor for problems on a regular basis, to catch problems before they take over. Sweep up fallen leaves or soil. If weeds grow in your greenhouse, get rid of them. But don't just worry about what is inside the greenhouse. If weeds and debris builds up around your greenhouse, insects will have a hiding place and can easily pop indoors. Choices you made in flooring and benches will also help or hinder in sanitation. Plastic flooring may be cheap, but molds and mildews will build up and it can be treacherous to walk on. Wooden benches can be harder to keep clean than aluminum or plastic. Greenhouses are becoming popular additions to the home landscape. Before you jump in and build one, be sure you can maintain it and have time to deal with the plants inside. If you need more information call your local county extension office. |
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University of Arkansas • Division of Agriculture |
Mission
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So
you think you want a greenhouse. You envision twelve months of fresh vegetables,
amazing tropical flowers and plants galore. But there is more to it than growing
plants. First you must build the structure. There are many considerations to
that -- from size, and materials to cover it, to heating and cooling and
ventilation. Then there is the time involved to take care of the plants.