A thermometer is, of course, a simple, accurate guide to garden temperatures in general and greenhouse heat in particular. I have been keeping an eye on the Max-Min from Europa Manor, which specialises in greenhouses and accessories. It features a big, curved display rather like a car's speedometer, which is easier to read than the more conventional column of figures. Switching from red to blue when the temperature dips below zero is another example of good graphics. The 'max' and 'min' needles share the same logical colour coding and are reset by turning a button.
The thermometer is designed to be free-standing or to hang from a wall. It costs pounds 13.35, or pounds 14.70 including postage, direct from Europa. The ideal location in a greenhouse is central and at about chest height.
Europa Manor Ltd, Appletree Road, Chipping Warden, Banbury, Oxfordshire OX17 ILL (0295 660588).