Greenhouse Accessories, Heating and Ventilation
When you have got your new greenhouse built the next thing to think about is greenhouse accessories. However large your greenhouse is, I bet you will wish it were larger and that you could fit more into it!
Temperature Control in Greenhouses
Keeping your Greenhouse Cool
There are two things to consider in keeping your greenhouse at a reasonable temperature. First you don't want it too hot. Usually there is an opening light (window) or two in the roof that you can open and close. Unfortunately this involves you being up at 6am in the summer and around at night to close it again. Fear not – there is an automatic vent opener available that will do the job for you. They're not expensive and clip onto the window using a hydraulic tube to push the window open and close it again.
To avoid excessive temperatures in a greenhouse, especially a large greenhouse, it’s important to have an adequate number of vents – Louvre vents are particularly easy to install into existing greenhouses and can also be fitted with an Automatic Opener for reliable operation.
You can also whitewash the greenhouse in the summer to reflect light and heat away, but this is a bit of a chore to both apply and remove. Another solution is to use shading materials to keep excess heat out.
OK, we now have the greenhouse cool enough in summer but what about keeping it warm enough for the plants at the beginning and end of the season?
Heating your Greenhouse
You will need a heater for this and to ensure the costs are kept reasonable, it's a good idea to insulate the greenhouse. There's more information here on Greenhouse Heaters
When it comes to heating your choice will be limited by what is available on your site. Most allotment holders will use a paraffin heater, they are pretty economical and many allotment shops sell it at lower than 'shop' prices. You can buy different sizes for different greenhouses as well.
At home you may have electricity from the house, which allows you to run with tubular electric heaters or fan heaters. The fan heaters have the benefit of circulating air and some being usable as a cool fan as well.
You can also use both natural and propane gas heaters as well. For natural gas, you will need a suitably qualified installer.
Insulation for the Greenhouse
The best option I've found are Heatsheets from TwoWests. You can use ordinary bubble plastic, often used for packing things, but heatsheets are designed for the purpose. Still, free bubble wrap is as cost-effective as you can get!
Measuring the Temperature
Finally, you will find a maximum and minimum thermometer invaluable to check you are keeping temperatures in the area you want.
Greenhouse Growing, Coldframes etc. Further Information