Air exchange and climate control
Healthy plants need moving air. Every grow room needs at least one oscillating fan to provide continuous air circulation. Moving air has a number of benefits for plants.
At a minimum, moving air should stir all the plant’s leaves to ensure fresh air reaches the leaf stomata. In a still environment, stale air can accumulate on the undersides of leaves around the stomata and hinder efficient gas exchange. This leads to undesirable effects such as suppressed plant growth; weakened stems, drooping leaves and other symptoms that reduce plant performance.
Moving air significantly strengthens plants; stems and petioles become thicker, stronger and tougher, and final yields are higher.
Moving air also helps the humidity cycle in the growing environment by aiding evaporation. It also prevents pathogens caused by moisture build-up on leaves during transpiration. Moulds love nothing more than a warm, humid environment.
AIR EXCHANGE
With a higher budget, introducing an air-exchange system promotes better growth. Air exchange requires a fresh-air intake and a stale-air outlet.
With an even larger budget, fitting an activated-carbon filter into the ductwork will minimise odour.
Air intakes are passive and can take different forms; however, they are always located at the bottom of the grow room, either in the floor if it is raised, or in the wall. When placing openings in the grow room, the main consideration is light control. A simple gap, vent or series of openings will provide enough airflow, but may be indiscreet with regard to light. Using a length of ducting with a bend or configuring a double wall stops light leaks. The easiest thing to remember is that light cannot travel around corners, so introducing a setup with some type of bend keeps your grow discreet. Also provide some form of pest barrier to deter any creatures that want to get in and feed on your plants.
An air intake means there will also be an air outlet or exhaust system, ideally with a carbon filter attached. Exhaust systems remove stale air and heat from the grow room and bring in fresh air. Where possible, venting outdoors is desirable to prevent heat build-up in enclosed spaces or the recirculation of the same air back into the system. This can often be challenging, but ducting is the solution to air-distribution problems.
The capacity of the exhaust fan is determined by the volume of the grow room. By multiplying length × width × height, you obtain the volume of the grow room and can determine which fan is suitable.
CLIMATE CONTROL
Plants thrive when the climate is controlled in terms of humidity and temperature, with some parameters ideal for vegetative growth and others for flowering.
Humidity can be easily controlled with a dehumidifier; dual-action devices are also available that humidify or capture moisture as needed.
During vegetative growth, a humid, warm environment increases growth rate, while lower humidity and temperature increase bud development.
Temperature can be controlled with small portable air conditioners. Many humidity-control devices and heaters come with built-in thermostats and hygrometers, so they switch on and off according to environmental requirements. Simply set them up and be confident that your plants thrive at every stage; automating all this makes growing much easier.
