A greenhouse is an enclosed structure that provides a consistent environment to the plants inside. Properly controlled heat and humidity is essential to the greenhouse's success. Although some greenhouses are simple and have few environmental controls, some greenhouses have complex heating, humidity and ventilation systems that allow different parts of the greenhouse to store divergent plant varieties.
Choose a good location for the greenhouse to give it enough heat to store plants. The West Virginia University Extension Service recommends a south to south-easterly side of a building or shade tree. This give the greenhouse both heat and cooling throughout the day. Growth is maximized if the heat and sun are at their peak early in the day.
Add heating to a greenhouse to prevent the freezing of plants and to increase seed germination rates. The amount of heat required for a greenhouse depends on the desired indoor mean temperature for most of the plants inside, according to the Clemson University Cooperative Extension.
Choose between space heating, radiant heating or zone heating according to your needs. Space heating is the heating of the air inside the greenhouse. Radiant heating heats the soil of the plants directly. The soil is warmer than the air with radiant heating. Zone heating allows you to add heat to the areas of the greenhouse needing it. This is ideal for greenhouses growing several types of plants.
Humidity is needed in the greenhouse to keep plants from drooping. Excess humidity in the greenhouse may cause disease by making large puddles and condensation on the leaves of plants. The greenhouse structure is often manipulated to guide dripping condensation to a rain bucket for later use. No-drip plastic surfaces are also available for greenhouse construction.
Install two air handling systems in your greenhouse to help control temperature and humidity. One fan is dedicated to an air exchange system while the second fan is for air circulation. This prevents condensation and stagnant, hot air that breeds fungi.