[Kleftiwallah]

Good morning everybody, 
our greenhouse is two greenhouses butted end to end and the entrance is not on an end but situated in a corner of a long side.  Along the opposite wall to the door I have grown about six melon plants all doing well (ish).  The one plant opposite the door isn't doing too well, leaves appear flacid and limp.  I think the cold air coming in through the door is chilling the plant. 

I am now keeping the door closed as much as possible, I'm hoping this one plant will perk up.

Waddya think?   Cheers,  Tony.

[snowdrops]

Could be, could you construct a sort of baffle in front of it so the door can be left open as I’m sure some days it needs to be. Even if it’s only a sheet of polythene draped in front?

[Kleftiwallah]

An admirable suggestion snowdrops, I'll look into it (or around it)!

Cheers,  Tony.

[Hortic]

I found a caravan door fly screen to be very useful, the kind that is made up of vertical strips. Hung on the open door it should allow air to circulate but keep heat in.