One of the most overlooked environmental factors affecting indoor plant growth is airflow. Good air flow assists temperature control, CO2 replenishment, reduces humidity and lowers the occurrence of certain diseases as air movement across the plants assists photosynthesis and transpiration which plays a major role in calcium transportation, preventing blossom end rot and tipburn in certain plants. One of the most effective methods of cooling a room is by having good ventilation and airflow drawn in from outside and vented out again.

Horticultural extractor fans are used to remove warm stale air from grow rooms. An extractor is essential for the maintenance of an optimum growing environment. The constant removal of stale air will lower the humidity and maintain higher CO2 levels.

If an adequate input of fresh air is not maintained then plant growth will virtually ceases. Most plants species will grow most effectively in the temperature range of 20 - 28 Degrees Celsius, so the mid twenties would be optimal.

It will not be difficult to maintain this sort of temperature in your room whilst the lights are on as they are a great source of heat and as well as light. If the temperature becomes too high, a simple extractor fan should serve to reduce it. This extractor can be easily linked to a thermostat to ensure that your room never reaches the high temperatures that can have a negative effect on growth rates.

When your lights are off, you should expect a gradual decline in temperatures. In the colder parts of the year, they will drop well below the ideal growth range. Research has shown that night cycle temperatures are just as significant as day cycle temperatures in plant production and it is in fact the relationship between the two which has the most effect on the final shape and productivity of the plant.

It is important to avoid large temperature fluctuations between the day and night cycle as this can lead to weak and poorly formed plants. It is ideal for most species to try and bring day and night temperatures as close together as possible and this is not as difficult as it sounds.

The amount to ventilation required to maintain the ideal temperature range depends on such things as the temperature of the incoming air, the heat load from lights in the room and the amount of air drawn into and flushed out on a regular basis. Airflow patterns should be considered in the design of any room. The placement of fans, vents and air mixers needs to be carefully planned to create good air movement in through the inlet vents, over and under the plants and out again. For odd problem areas where still, moist air is collecting, small mixer fans can be installed.

Fans in a grow room, not only vent out humid air but bring in drier air to the growing environment and this is essential for not only good plant growth but also disease prevention. When humidity levels are high, condensation can become a problem.

Condensation on plants provides the perfect environment for many types of fungi and bacterial diseases to infect your plants. It takes only a few hours of this for most diseases to infect plant tissue and take hold, so reducing your humidity levels and preventing condensation are one way of protecting plants from disease. There are two types of fans commonly used in growing areas - intake and extraction or vent fans.

Intake fans pull air into the growing area, extraction fans push it out. Ideally both should be used to vent out and draw in fresh air, inside the growing area, air needs to be mixed and circulated over the plant surfaces.

Circulation or mixer fans, which may be wall mounted or pedestal types carry out the essential function of mixing the cooler, drier fresh air being brought in, as well as any CO2 enrichment to create a perfect constant temperature and prevent cold drafts from stressing the plants. These fans should be placed carefully because the main objective is to not only get air circulating and mixing in the lower levels of your crop to reduce humidity and disease problems, but also over the tops of your plants to help achieve maximum growth and yields. Checks on CO2 levels, temperature and humidity around the growing area and in the crop will help give information on placement and allow you to adjust fan positions when needed. Ideally, fans should be linked to a thermostat - triggering increased air flow and ventilation when temperatures start becoming to warm.

REMEMBER: Air movement with the correct sized fan, well placed mixer fans to displace air around plant surfaces and fan controllers to get maximum climate control are vital to the success of your indoor crop.

Article courtesty of S. Dop of http://www.grotec.co.uk. Distribution by HydroponicSearch.com - The Hydroponics Gardening Search Engine & Educational Community Site.