One of the most important aspects you need to consider when growing plants and vegetables is your greenhouse air circulation system. If you have a greenhouse heater installed simple physics tells us that the hot air that is generated will rise to the top of the greenhouse and cool or cold air will rest on the bottom – right where your plants are. It’s imperative, therefore, to ensure a uniform distribution of warm air throughout your greenhouse and to achieve this you need to ensure good air circulation.
Some greenhouse heaters work by heating a filament within the heater and then using a fan to help circulate the air throughout the greenhouse. This is fine, on one level, but if you do decide to go with this option you’ll find that you’ll need a few fan-assisted heaters strategically placed around the greenhouse (depending on it’s size) to ensure the air is circulated evenly.
This can be achieved by positioning your heater fans in the corners of your greenhouse. If you are only going with two fan-assisted heaters and this is all you plan to rely on for your greenhouse air circulation then place them in opposite diagonal corners as this will ensure a circular movement of air around your greenhouse. You also need to hang your greenhouse air circulation units at least 3 feet above your plants and attempt to leave some space underneath your plants by placing them on a bench so that air can circulate all around them and reduce the humidity. However, be careful not to place your heat fan aiming directly at nearby plants as it can cause them to dehydrate.
During the summer months when the heating of your greenhouse will (or should!) come from the sun and you’re planning to use the cool-air summer time fans on your heaters, then you have to be certain that the fan of the product you buy is on an ‘on-off’ configuration and not linked to your thermostat otherwise the fan will constantly turn itself off when the thermostat reaches its “switch off” level. The cool-air function during the summer is just as important for greenhouse air circulation during the summer months as the heating function is for the winter months.
And of course, weather allowing, don’t forget to open your greenhouse door and vents!
Fresh air, heated (or cooled), for your plants and vegetables is imperative otherwise they will be subject to slow growth, low yields and prone to disease and so ensuring your greenhouse air circulation system in working as it should is one of those little important things that tends to get overlooked.