With larger glasshouses, one square meter of ridge ventilation for each five square metres (20%) of floor area provides the ventilating capacity to give one complete change of air within the greenhouses every two minutes. Unfortunately, shading limits the light plants receive. As plant growth depends on light, only the minimum amount of shading should be used to keep temperatures below about 25-27ºC (77-81ºF). Otherwise, allow as much light in as possible, particularly when growing edible plants such as tomatoes. There is often no need to shade sun-loving plants such as succulents although the greenhouse is more pleasant to be in when shade is provided. There are various means of shading greenhouses and conservatories: It is sometimes necessary to temporarily remove panes from glasshouses to assist ventilation in heat waves Polyethylene mesh or netting (shade netting): is usually placed inside the glasshouse and fixed with clips. External fitting is better but harder to arrange. This is a cheaper option than blinds. The plastic is likely to biodegrade over a number of years but is not expensive to replace.

They can also be paired with an auto louvre window openerto turn the louvre from manually openable, to automatic opening, to cut down on having to open and close the louvre window yourself. In changeable weather, vents and doors often have to be left partially open to limit sudden increases in temperature. Larger greenhouses may, at high cost, be fitted with automated ventilation and shading As suggested a louvre window should be fitted near the base of the greenhouse rather than higher up. It will fit between the upright glazing bars and will replace a piece of glass. Detailed fitting instructions are supplied.With horticultural glass, you would simply replace a panel of glass with a louvre panel. With long pane toughened glass you would normally be supplied with one additional panel cut short to accommodate a louvre if required. Fitting a second louvre may involve buying an additional panel of glass. This particular photograph of a louvre is 18ins x 24ins fitted with toughened glass in the blades. It is used as a guide photo only. DeliveryBe alert for signs that shading and ventilation are required; sun-flag (partial collapse), leaf scorch, desiccation of tender young plants and shoots

Keep your greenhouse cool and your plants healthy with our selection of greenhouse vent systems, auto vent openers and accessories. Good ventilation lets in the fresh air that plants need for pollination and growth. It also reduces humidity and makes the greenhouse less inviting to pests that otherwise might turn it into their new home. Greenhouse Megastore offers a variety of airflow solutions for growing structures of all sizes, including roof and side vents, louver windows, poly side venting, end wall venting and aluminum shutters. Our products range from heavy-duty to the most economical. Whether you need a complete greenhouse ventilation kit or a new automatic greenhouse vent opener, our greenhouse experts can help you find the right product. Fit automatic vent openers to ensure roof vents open even when you are not around. However, remember that since they work by the expansion of wax in a cylinder to open the vents, it takes time for the wax to expand. Provide plenty of alternative ventilation (i.e. doors and side vents)to prevent damaging temperatures occurring before the openers respondGreenhouses with horticultural glass (2ft x 2ft overlapping panes) will simply have one of the existing glass panes replaced with the louvre window. Increased airflow will help keep humidity levels down and avoid the conditions that certain fungal diseases - such as botrytis - enjoy, and the adjustable cooling effect of the louvre window in the summer will be welcomed by plants and gardeners alike. Glass blades for the Louvre Window Kit are not supplied, but the pane you will have to remove to fit the unit can be cut to minimise waste. Glass panes are also available from glass merchants or glaziers who will usually cut the glass into slats to fit the kit. The Louvre Window Kit replaces a 61cm (24") square pane.