Greenhouse thermometers and shade netting
You only know how cold your greenhouse got overnight if you measure it. A max-min thermometer records the lowest and highest temperature since you last reset it. In summer the problem turns around: without shade, a greenhouse can pass 40°C and scorch your plants. Shade netting cuts the heat on the sunny side.
Brannan digital max-min thermometer
Simple max-min thermometer from a British maker
£13 at Amazon · 4.5 stars (2,184)
Digital max-min thermometer
Thousands of reviews, records the overnight low
£13 at Amazon · 4.5 stars (3,672)
Elixir Gardens 40% shade netting 2 m x 10 m
Light shade for tomatoes and cucumbers
£12 at Amazon · 4.6 stars (281)
Greena 55% greenhouse shading
Heavier shade for a small greenhouse in full sun
£12 at Amazon · 4.1 stars (786)
Prices and ratings from Amazon.co.uk when we checked. Affiliate links. We have not tested these ourselves.
What to look for
- Hang the thermometer at plant height in the shade, not in direct sun.
- Check the overnight low on cold mornings in autumn. It tells you when to switch on the heater.
- Fit shade netting on the outside where you can. It stops heat before it gets in.
- Shade paint on the glass is the other option. It washes off again in autumn.