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Greenhouse Ventilation

Understand the importance of venilation in a greenhouse

Greenhouse Ventilation

greenhouse | grow your own

Excellent Ventilation is essential if your Greenhouse crops are to thrive. Ventilation controls the temperature and humidity of the air in the greenhouse, both of which are essential factors. Excessive humidity can lead to mildew and other fungi proliferating, and excessive heat can quickly dry out and kill your crops.

Greenhouse ventilators are generally positioned in the roof and sometimes in the sides of the greenhouse. In the ideal world around 20% of the total floor area should be dedicated to ventilation, so in an 8 x 6 foot small domestic greenhouse, there should really be around 9 square foot of ventilation. Unfortunately it is rare that a greenhouse supplied as standard will provide any where near that much ventilation.

Through the seasons the ventilators should be used differently. During the spring just the greenhouse roof ventilators should be used. This is will lead to a slow flow of air as the hottest air escapes through the roof. As temperatures hot up during late spring and summer side ventilators (or the door) should be opened. This will result in a large increase in air flow as cool air enters the greenhouse from the side and hot air escapes through the roof. Even during the cold of winter and early spring ventilation is vital during those still, cold, and damp days when the air is stagnant and not moving. A little roof ventilation, ideally with some heat, is important.
Greenhouse Roof Vent costing 20
Remember that it is always better to over-ventilate than to under-ventilate so consider fitting a suitable louvre window in the side of your greenhouse to increase cooling draughts during the summer, and an automatic greenhouse roof vent which will open whenever the temperature is above your chosen set value (pictured above).

Greenhouse ventilation fan

If you intend to grow a self-sufficient crop of fruits and vegetables in your greenhouse, then it is even more important to ensure that ventilation is taken care off. Therefore it is well worth investing in an extractor fan (fitted into one of the panes of glass in the roof) which will completely replace the air in the greenhouse every few minutes on the hottest days. Using a thermostatic controller enables the extractor fan to be run automatically, and it can also be powered with environmentally friendly solar panels.

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Article Published: 12:29, 9th Jul 2008

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