On Mon, 18 Apr 2005 09:51:38 GMT, "peterlsutton"
wrote:

I have just bought a large (22" x 15") Sankey 22 watt heated propagator for
£20. I put some cuttings in it and switched it on. With an ambient
temperature of 62F, a thermometer pushed to the bottom of the pot registers
a temperature of 98F, in the middle of the pot it is 85F and resting on top
it is 72F. I have compared the thermometer with another and am happy that
it is accurate. The propagator is placed on a sheet of polystyrene.

This sounds as though it could fry cuttings pushed in too deep. What
temperatures should I be using and at what measurement point. It has only
been on for 36 hours so far and nothing has died yet. Presumably this steep
gradient is normal, irrespective of the actual temperatures.

Yes, and laterally as well - it's quite patchy. A lot will depend if
your rooting medium is in pots on sand or similar or if it's direct
into the propagator base. If the latter it will probably be on the
warm side if the cuttings are too deep. I use one of these for
germinating Cyclamen seeds for which I want a constant18C, I've hacked
a proper thermostat into the mains lead. By proper I mean reasonably
accurate (+/- 2C or better) and above all repeatable.Suitable
instruments are available on the electronic surplus market. This one
is OK.
http://www.highland-weather-shop.com...tat-Controller

I've had a couple of these from him, one runs my workshop heating with
the help of a suitably rated mains relay, the other controls a
propagator like yours. It's reassuring to know that what you see on
the display is what you get.

=================================================

Rod

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http://website.lineone.net/~rodcraddock/index.html