Following the very diverse responses I had to my requests on various forums for help with my mysteriously chlorotic Anacamptis papilionacea I decided to go on instinct and install a soil warming cable in the plunge bed. I responded to one earlier suggestion that I should remove all the insulation I had as soon as possible by hastily doing so only to be rebuffed for doing so by the last bit of advice I received, which was actually the best advice I had received in many ways. But it was too late and I hoped that a soil warming cable with a thermostat would also reduce the heating bill (but I am not sure about that!) so I went ahead and did it. I contacted Two Wests & Elliot who I have used previously and they recommended a 40' cable and a Professional 3Kw rod thermostat. I spent pretty much all day yesterday fiddling about setting it up, luckily it was a mild day although a lot of the grit sand I had bought was still frozen solid! The connecting the cables was in no way as straight forward as they suggested - even a very electrically competent friend was a bit stumped by the confusing instructions and the actual wiring itself was very fiddly, but by lunchtime it was ready and I managed to get all the orchids in and put to bed tonight. Of course the weather has now turned but February often has a cold snap... Rather worryingly I am now at full capacity already, I have two more beds on trestles ready to get kitted up when the next crop of seedlings (mainly more Anacamptis morio and Dacts) are ready to deflask and at least this time I will know what to do!