[VeggieVirgin]

We're planning on making a heated propagator using damp sand and a soil warming cable. Our dimensions are approx. 22 in x 54 in.

Can anyone recommend a specific make of warming cable and thermostat? There are loads of versions on the internet, and I'm feeling a bit boggled. I reckon a 6 m cable would be sufficient for the size we're proposing, but please let me know if I've done my sums wrong!

Please feel free to point out any pitfalls too.

All help appreciated!

[AlaninCarlisle]

I made mine about ten years ago. It's 42in x 24in and I have a 6 metre Parasene cable and thermostat. I'd say your calculations are about right, but if there is an 8 metre cable that might be even better. In my experience you'll need about 30kg of sand. Not sure why you want to use damp sand, I found dried sand better as it seems to find its own level instead of you having to faff about smoothing it

[VeggieVirgin]

Thanks, AlaninCarlisle.

Websites say damp sand conducts heat better than dry sand, but we'll probably use dry sand then wet it once it's in situ.

[Eblana]

I made mine last year and used a 12 mtr cable but my bench is 18" x 72".  I put insulation and plastic on the inside of the 'box' put a couple of inches of sand in the bottom, coiled the cable back and forth across the sand, put another couple of inches of sand and then put a layer of chicken wire in topped it off with more sand and then watered it well.  The insulation stops the heat getting out and the chicken wire and water help to conduct the heat.  The thermostat should be near the top but covered by the sand.  I used peresene cables and thermostat.