greenhouse temperatures

[sallylockhart]

Hello,

Can anyone tell me what an ideal temperature for a greenhouse would be, and how best to maintain it? It's an aluminium frame glasshouse - 2m x 2.5m.

On saturday it was 25degC at head height (5foot) (sunny day with windows open - about 18degC ish outside), and yesterday it reached about 15 (not so sunny day, but still warm - 14-15degC ish)

Is this kind of fluctuation normal? And will it be OK for my tomatoes and courgettes?

Also, I have just discovered that the greenhouse has automatic opening devices on its louvres and skylights. We discovered this after trying in vain to get the windows to stay open earlier on in the year and then thinking we had invisible pixies on the first sunny day when all the windows opened on their own  :o

So - can anyone tell me how these work? (not fussed about the physics - more about whether screwing the black handle in will make the windows open at a higher or lower temperature and how to calibrate them).

cheers

sl

[sallylockhart]

[tim]

How long's a piece of string? Especially  if you're a mile away from it!!

1. You will NOT maintain an even temp however hard you try. Yet fluctuating temps are an anathema.

2. Toms etc like over 50F & under 80F. A small 'house can quickly exceed 100F.

3. The only way you can assist the louvres is by using a fan and/shading. Better less light than overheated.

4. Damp down the floor frequently.

5. The actuators are based on mineral expansion & should be adjustable to open sooner or later. In summer - we have 24 vents open 24/7 & still overheat.

6. You are not alone!!

[euronerd]

Tim's right I'm afraid. I experimented with a mini greenhouse inside the main one, and still had a variation of 50º on more than one occasion.

If you screw the black thing in, the window opens at a lower temp (or at least mine do). The only reliable way of calibrating is to actually be there as the heat begins to rise.

Geoff.

[caroline7758]

I've found shading paint pretty effective- and cheap! Paint in on in early summer and it just wipes off when you don't need it any more. I've also been lazy and bubble-wrapped my greenhouse in winter then left the bubblewrap on as shading in the summer! Mine is a makeshift, lean-to built against a garage & only gets sun in the morning but I've still managed to grow tomatoes in it, so don't panic.