Soil Warming Cables

Answered by Harrod Horticultural Posted in Category Propagation

Dear Martin

Is it all right to use an old wooden drawer as a tray for the sand and cables? I'd also like a compatible thermostat and want to know the best place to position it. Can you help?  


David Thurston

Dear David

Many thanks for your recent message regarding the soil warming cables we supply and a compatible thermostat. The cables are not supplied with a thermostat and can be plugged into the mains to give a constant source of heat but are compatible with a large number of thermostats – any model with a two pin plug will fit the cables.  

Moving onto the propagation bench you’d like to build, and your proposed idea for housing the cables and in an old wooden drawer seems ideal. Just make sure the drawer is large enough to leave 8-9cm between the loops in the cable when laying it in position or it may overheat.

In my experience, it's best to position the thermostat sensor as near to the area the heat is required to achieve an accurate level of control. In the case of the warming cables, you're interested in the temperature of the soil in the seed trays around the root zone of seedlings, so pushing the sensor into the compost should give the best results.   Likewise with a greenhouse heater; try to position the sensor at plant level as it's this area you want the thermostat to monitor and heat.  

I hope this information is of help and happy propagating!