On 09/02/2017 19:26, Judith in England wrote:
On Wed, 8 Feb 2017 10:02:37 +0000, Martin Brown
wrote:

snip




Thanks to you and others for excellent suggestions


I've built propagating frames like that for many many years.
polystyrene underneath then polythene sheet over the base and up the
sides (sides being at least 4 inches deep) then about 1 1'2 inches of
sand, the cable snaked back and forth across the base with the wires
around 3 to 4 inches apart, then cover with another 2 inches of damp
sand. Cover with black polythene to stop the sand drying out and to stop
any roots getting into the sand.
A rod thermostat through the side of the frame so it sits just below the
surface and between the wires to get the best reading.
If you are going to use it for cuttings, if you can build a frame around
it covered with polythene sheeting, the front should have a curtain that
seals at the sides and goes down over the front. If you have a string
stretched tight across the front then you can tuck the sheet under it
and get a good seal, this will help to keep the humidity high and stop
wilting.
Good luck
David @ a dry but cold side of Swansea Bay