Greenhouse Climate | Environmental control
Climate plays a major role in how well plants thrive year-round within a greenhouse
Plant hardiness zones
Maximizing the growing season
Regulation of temperature is done through one or both of the following ventilation systems:
1. natural (roof vents, windows)
2. mechanical (fans).
Additionally, in colder regions greenhouses require additional heating during the winter months. Ventilation allows the exchange of the moist greenhouse air with the drier air from outside. Greenhouses are vulnerable to overheating from the spring until the autumn; overheating is one of the most common mistakes of a novice greenhouse gardener.
There are typically three places air leakage occurs in a greenhouse:
1. The door
2. The roof vents
3. The side vents
Side ventilation is less effective than roof ventilation. A rule of thumb is to have 1 sq m of ridge ventilation (roof ventilation) for every 5 sq m of floor area. This will provide the ventilation capacity of one complete change of air within the greenhouse every two minutes.
For effective ventilation monitor the greenhouse temperature with a maximum-minimum thermometer. If temperatures are allowed to exceed 27C plant damage is likely to occur. Automatic roof ventilation openers are an excellent way to regulate the greenhouse temperature if you are not at home. During hot days it is best to provide maximum side ventilation in case the roof ventilation opener does not start.
Shading is another way to reduce the overall heat within a greenhouse, unfortunately, shading limits the light the plants receive, thereby reducing overall growth. Limiting the amount of shading when temperatures are below 27C is the best protocol. The types of shading include:
1. External blinds – they provide maximum cooling as they prevent the sun’s rays from entering the greenhouse
2. Internal blinds – not as efficient as external blinds since the light has already passed through the glass and generates heat, however, they are much more easily automated and provide less interference with roof vents
3. Netting – mesh simply clips onto the greenhouse structure—the cheapest option
Maintaining optimum humidity
Determining relative humidity
Ultimately, the right greenhouse for you is one which you will use for a long period of time – one which meets your demands and fits in with your lifestyle. Once you’re happy with your choice, read our guide on getting the most out of your new greenhouse. What works for some growers may not meet your requirements. More complex plans may be just up your alley, sometimes those plans can stifle success. Grow smart, not hard! Gardening advocates advise that you start with a basic, structure like a pop-up greenhouse so you can get the hang of your new plant responsibilities. The full-size challenges of Backyard Greenhouse gardening await! If you’re looking for more in-depth greenhouse reviews or comparisons, click here to check out the top reviews.