To open are leave closed ?

Hi
I have a mini-greenhouse for the 1st time and I am trying to grow on some bedding plug plants. I potted them up about 2 weeks ago and since placing in greenhouse have kept it closed. Should I now be opening it during the day ? the average daily temp is now 10c .Would appreciate advise.

 

The main thing I'd be worried about if I was leaving the door open, is it exploding when a gust of wind comes (assuming its a 'blowaway' type plastic one).

It sounds daft, but trust me, I've seen it happen. A gust of window comes, inflates the greenhouse like a balloon, and then it just bursts

I have a 'blowaway' now, and on warm days I leave the door open because it gets roasting in there, but any hint of wind and I seal it up.

 

Open it or the plants will cook, as a glimmer of sun will set the temperature soaring. I've lost more early season seedlings/young plants to excess heat than lack of it.

 

Is that outside? As others have said direct sun will make the temperature soar. Pop the thermometer in the greenhouse and try not to let the temperature go over 25C if you can, and opening it around 20C would be better.

 

I bought a 6x4 aluminium a couple of weeks back and got caught napping by the sun...lost nearly all my rooted cuttings in one day...after all the effort and success on the indoor window sills it's a real blow... I've shaded it now...ah well!...live and learn.

 

The bigger the greenhouse, the easier it is to control the greenhsoue (although if you leave it closed it will still cook :( but in Summer its hard to keep 6 x 4's cool, much easier with 12 x 10 and bigger.

With smaller greenhouses yo can open door and vents, but all you are doing is creating draught, which increases transpiration stress. With larger greenhouses I guess there is less thermal gain, per unit area, so the heat can be dispersed more easily - so plenty of vents and, say, a louvre low down creates a convection current to cool the house, which is kinder to the plants.

Wetting the floor will help reduce the temperature (evaporative cooling) and the plants will appreciate the increased humidity). For cuttings probably worth having some shading over them - they won't need bright sunlight until they are rooted and growing strongly under their own "steam".