[gremlin]

I keep seeing the expression in books and sometimes on seed packets "grow on in gentle heat".

Can anyone give me a clue as to what temperature gentle heat is?

OK I know that "gentle heat" for a cactus is different to that for parsnips, but the expression is used in general gardening books, and is not plant specific.

[mumofstig]

I count my spare bedroom window sill as gentle heat - it's not cold but it's not that warm either 

I think it usually just means keeping things a little warmer than frost free, DD sets his thermostat for a min of 55F (12.8C) in his greenhouse at this time of year. Hope that helps

[sunshineband]

I always think of it as 15C as that is what our kitchen never falls below at night

[gremlin]

 a bit more googling around on g/h temps:-

"frost free" +2 (or 4, or 5) C
"cool"  +7 C
"warm"  +13 C    (I will include your comments on gentle heat here)
"tropical" +15 C
"heated" +18 C

Most amazing advice found so far:- "a candle will keep your greenhouse frost free"
That must be one great big candle, or a tiny greenhouse.