Shading

Yeah, I need to work on the other bit

 

Has anyone tried rigging up a blind attached to one of the thermo roof vent thing so it only gets shaded when it really needs it? I have a small greenhouse as well and it's not in an ideal position. In the spring and autumn when I go to work in the morning it's too cold to open the door and the one auto roof vent is not enough to keep it cool. summer Is not so much of a problem as I leave the door open but on the four sunny days we get each year the temperature does soar.

 

My blinds that I installed last year.



Made from old curtain linings and each panel is secured by the bolts in the greenhouse roof. Cost me nothing to make and I can take down some of the panels to increase light to other plants in the greenhouse.

 

Just out of interest, what do we reckon is the minimum/optimum light level for growing 'normal' greenhouse crops successfully? I used to use the commercial greenhouse shading, but thought it was a bit too dark.

 

I personally would look at changing the roof vent over to the north side if your greenhouse has that option, mine can do this and it's a halls one. It would involve taking all the glass out and moving the vent bar though, but I personally would do that instead of making compromises with the shading.

On the other hand you could create a wooden frame to go over the opening of the vent on the inside and then fix the blind to it somehow. Can supply you with some bolts if needed, if your greenhouse has grooves on the inside of the frame, which it should do.

 

I'd suggest buying an extra vent(s) John. Commercial greenhouses have continuous ridge vents to allow the heat to escape via the chimney effect, and I think that hobby greenhouses often have far too few vents. Not sure how many you have? but my small greenhouse has 6 panels and 4 vents (on alternating sides) and the large one has 14 panels and 8 vents. I open the vents on the side opposite the prevailing wind for gentle ventilation and both sides for normal summer ventilation. I don't use any shading - although, ahem!, the glass isn't exactly crystal clear at the moment!

I'd also recommend a louvre low down, if you are re-jigging things anyway, so you can get convection, particularly at those times in the season where you don't have to throw the door wide open.

If you are refitting a vent, and if its the same type as mine, make sure you get the hinge locks in the right place as I think that may be easier to do at initial construction than when taking a pane of glass out to fit / move a new one. Assuming the same as mine the vent hinge fits into the ridge member (in fact not sure how one would retro fit one as they slide in ...) and there there is a locking piece (a tube that also slots into the same member as the vent and has a retaining/locking screw) which prevents the vent moving side-to-side. Several of mine are not precisely located and the vents don't close accurately, so I have to "fiddle" them to get them fully seated when closed. But adjustment of the locking screws is inaccessible without taking half the glass out!! :( so I have never got around to fixing them.

Of course when my Alitex Cliveden arrives all will be perfect, and the pigs will be fed and ready to fly!

http://www.alitex.co.uk/national-trust-greenhouses/the-cliveden.aspx
a mere £25K for a 12' x 21' greenhouse

Only photo I could find of their ventilation, you can just about see the continuous (for 2/3rd the length) roof vent on the far side, and the prop-open lower vents (same convection effect as louvre) on nearside

 

eBay maybe ... worth a long-term email-me-search on the make/model as a keyword? - just in case the seller happens to know what type they actually have. You could resell the rest of it as a special vent-less structure

EDITed to make more sense