Greenhouse advice

[jwrmo]

Hi all,
I need a little help deciding on a greenhouse. After a year and a half of research (and saving) I am ready to purchase. I have narrowed down the choice to two models. I have never owned a greenhouse before and am not sure which one is better for growing orchids. I have been growing in my basement for a while and believe that it was good practice for owning a greenhouse. I am concerned about two items in particular. One, the sidewall height, will I have to stoop in the greenhouse and will it really be a problem. I am only 5’ 10”. The other concern is the wall thickness, do I really need a 10mm thickness in the Midwest. I have included the dimensions of the models I am considering. Any and all help would be appreciated.

Model Juliana Premium 9.9 Halls Optimum 96
Height 7' 10" 8' 1"
Width 9' 1" 8' 2"
Length 12' 2" 12' 8"
Sidewalls 4' 9" 6' 3"
Covering 10 mm twin wall poly 6 mm twin wall poly

[harrywitmore]

I'm short but I would opt for the taller sidewall. I'm not sure where you are in the midwest but what I would want to know is how much will 10 mm increase the r value over 6 mm.

[stonedragonfarms]

Where are you at in the midwest? Winters are very cold here in MI, given the choice of the two I would opt for 10mmtwin wall, though imho, triple wall is even better if you are hell bent on rigid poly. I have double inflated poly with about 2" of space between the sheets--which is very good insulation... How will you be heating, is the gh to be attached or free-standing & what are your target night temps?
Adam

[jwrmo]

Sorry I guess I should have included additional information. I am in St. Louis MO and it does not often reach zero degrees and not for very long. Average winter temp is 21. I am planning on heating the greenhouse with a 25,600 BTU electric heater or a 17,100 BTU heater if I go with the 10mm poly. It is a freestanding poly greenhouse kit. I am not sure that I can modify the poly in any way. Thanks again for the assistance. Jess

[stonedragonfarms]

Jess: 21F is cold!--though it's often colder here... I would shoot for 10mm poly, your pocketbook will thank you for the extra insulation that it provides when it is super cold out there. I always think that a bigger heater is a better heater, you would rather have it warm right now, rather than struggling to overcome the cool, but given the size of your greenhouse, either of these should suffice, unless you are hoping on running a hot house (85day/70night), then I'd go with the bigger of the two...
Given the choice of the two, I would go for higher sidewalls (you will be able to make better use of bench space, as spikes on the rear of the bench will not have as much of a chance of hitting the slope of the roof, you will have more flexability with bench height and you will not have to stoop should you decide to run an aisle on either side of the benches in the house). You never mentioned, what is the door height for the two?
Adam