Insulating your greenhouse

If you are heating your greenhouse during the colder months, its a good idea to insulate it to cut down on wasted energy. Affix a layer of transparent plastic to the framework , leaving a gap of around (1 inch) 2.5cm between the material and the glass. The space creates an air pocket which reduces heat loss.

Taping a layer of bubble wrap to the frame work is another good form of insulation, but it will reduce the amount of light which enters the greenhouse, so could lead to weak and leggy plants. Consider just insulating the side which faces prevailing winds, that way you can still protect crops from the chilling weather, but adequate light should still reach them.

Before you put up insulation check that there are not any cracks or broken panes of glass, which would contribute to heat loss. Clean the panels to make sure that the maximum amount of light will enter the greenhouse, then make sure that your heater is working properly.

Venting your greenhouse

It is essential to set the ventilation in your greenhouse each day. In late spring and summer, open up the top and side vents in the morning before the temperatures increase. Even in winter there needs to be a change of air, otherwise the atmosphere will become stale, providing an ideal environment for diseases to build up.

If wind or rain is predicted keep the vents at or below horizontal to protect the plants growing inside. On colder days leave just the tiniest of gaps, but once gales hit keep them firmly closed.

Close the vents in the afternoon to trap the heat in the greenhouse, so it remains sufficiently  warm overnight. You should continue to do this even when spring arrives, until night temperatures reach around 10C (50F).

Supplementary lighting in your greenhouse

Do not forget as the days get shorter over winter, supplementary lighting may be required to encourage crops to keep growing healthily. Plants grow towards the light and if levels are inadequate they will end up weak and spindly in their search for what is not there.

Shading paint should be scrubbed off, any blinds removed, and the panels should be cleaned to make sure as much light enters the greenhouse as possible.

If necessary turn your pots daily so that the plants receive light on both sides. Actively growing plants do best if they are positioned near to the glass during winter, but seedlings should still be thinly shaded from bright sunlight until they are established.

In spring as the days get longer, you should shade the greenhouse with netting or paint.

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