Hello Leer1,

I'm not an expert on air mass, but I think the difference between the 10x12 and 6x8 can't be too significant. I'm sure some folks on this site have a great deal of information on this issue.

I think the greater issue is flexibility and the ability to move about. The 6x8 is essentially a galley design. No place to move but in and out.

I think the ability to move about in a larger greenhouse would be great.

Cheers.

DG

Usable wall space might be another consideration. The side panels of the 10x12 are 6Â 5" tall. With the base/foundation, our side walls are about 7Â tall. This will allow a 30" tall bench, a wire shelf above that, and a lower shelf under the bench top. So, three levels of plant space is easily possible (I generally have small pots of cacti and succulents.)

The side panels of the 6x8 are 4Â tall. The final height is determined by the height of the foundation added, so adding a 12" foundation could mean sidewalls about 5Â tall. For my plants, that might limit me to two levels of plant space.

The 10x12 does allows a bit more flexibility in floor plans. WeÂre building a long bench on each wall, and adding three peninsula benches off one bench, with standing spaces in between. Somewhere I saw a pic of a 10x12 with a U-shaped bench around all three side walls, and a small island workspace in the center. Not roomy, but possible.

Regarding aesthetics, I like the feel of the overhead space, but I admit the GH does "stand out" visually in the yard. A shorter GH would have blended in better with our landscaping. I like it when IÂm inside, but when IÂm outside I wish I could crank it down a few inches!

At least one member here has mounted a ceiling fan at the peak of the 10x12, another use of that space.

IÂve considered creating a "false ceiling" out of solar pool cover in the winter, to block off the peak and limit the amount of air IÂll be heating. (I already have three horizontal braces in place at ceiling height.)

IÂve wondered if the (roughly 10 ½Â) height of my 10x12 might help it feel coolerÂif the warmest air concentrates above the level of my head and my plants? But I have no knowledge to support that idea (my newly erected GH is still one big oven.) Maybe someone else has thoughts about thatÂIÂm too new to understand how warm and cool air behaves in these things.

The higher the roof the better in hot weather.
If you live where it reaches 90F when you have plants in it you will not be able to cool a lower roof GH without a mister or water wall.

Thanks everyone. 10x12 it is.

Posted by leer1 6 (My Page) on Thu, Sep 20, 07 at 9:20

Thanks everyone. 10x12 it is.
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If you buy a 10X12 HFGH be sure to read in the FAQ about this GH also do a search on this site before you start.
This GH needs a lot of modifications to it but with a little effort on your part it can be made into a decent GH for very little money.
The cost of the GH is less than the foundation\flooring\heating\cooling\grow lights\benches\heat mats\exhaust fans\vent openers\thermostats\thermal blanket\insulation\shade cloth\wiring\installing water.
Their are plenty of people here to help if you need it.

Here's the link to the Greenhouse FAQ section, where you'll find gardenerwantabe's excellent thread about modifying the Harbor Freight 10x12:
Greenhouse FAQ

Doing a search for "HFGH 10x12" will pull up tons of great posts with links to photo albums by many members. I would never have had the courage to build one without reading the great info in these posts and pictures.

Here's my blog about our 10x12:
Building the HF 10x12

Our experience has been just as gardenerwantabe says...the cost of the kit is less than all the other expenses for required "goodies." (But it's a pretty fun way to spend money.) ;-)
Sheri