Hello, I'm very new to growing in a greenhouse as well but will tell you what I've learned so far. As far as basic ventilation you want your ventilation fan at the highest point as possible,and your shutter intake at the lowest possible point opposite side of the fan. The exhaust fan should change the air in the greenhouse in 1-1/2 minutes. Fan capacity is rated in Cubic Feet per Minute (CFM). For your correct fan size in CFM, calculate your greenhouse Volume: lengthÃÂwidthÃÂheight, then pick the correct fan and vent to achieve. This post was edited by hnycrk on Tue, Jul 8, 14 at 22:26

If I ever decide to plant in the ground inside the greenhouse, I'll have to move the greenhouse inside one of the fenced garden plots in order to keep our cats out. That first year, or maybe the second year, we built raised beds along one side and I was going to grow stuff in them in winter, but the cats thought I was building them a nice warm kitty cat outhouse with big, deep beds of enriched soil. That put a halt to me growing anything in there. We moved those beds to the big garden, one wheelbarrow load of soil at a time. The cats don't bother the plants or the soil in containers in the greenhouse, but they wouldn't leave the raised beds alone. Our greenhouse is sort of at the bottom of a slope because our neighbor's land to the south of the greenhouse is higher than our land, and that would be an issue almost anywhere on our property as their rain runoff mostly all runs downhill towards us. So, a little water stands there by the greenhouse (more outside of it than inside of it) when we have heavy rain, but we don't have heavy rain very often. Our clay soil doesn't drain quickly but we are always so rain-starved that I don't mind having a little standing water. It beats tripping over the cracks in the ground when no rain is falling. Before we built the greenhouse, its site was a weedy mess, so the greenhouse sure was an improvement over what was there before. I always thought I'd have a paver or gravel walkway in there but we never got around to putting in that walkway and I discovered it works fine with just plain old soil under mulch. I was out in the greenhouse for a while yesterday and today and it is like walking into spring in the middle of winter. I really didn't want to leave it and come back into the house. Dawn

Hi Margaret, You have the same model 10x12 Harbor Freight greenhouse that I do. Ours has been up for almost 9 years now. I totally agree with kudzu9; it needs to be anchored to the ground. I know the Harbor Freight manual still indicates you can set the frame on the ground and fill it with gravel, but my latest version of the manual also has a page up front, with bold type, that says "IMPORTANT - Wind conditions vary from site to site...may affect practicality of anchoring methods substantially...it is always your responsibility to ensure that the greenhouse is properly anchored...etc." This is because many Harbor Freight greenhouse owners have had their completed structures roll across the yard and be destroyed...when they are not anchored. Here is a link to the blog we did about building our HF greenhouse. There's a section on how we did our foundation. As you've noticed by watching videos, there are many ways to tackle anchoring the base...but it really must be securely anchored. Building our Harbor Freight 10x12 Greenhouse The other thing the manual doesn't tell you is that the panels must be attached to the frame more securely than the kit specifies. If you browse Harbor Freight threads in the archives here, you will also find threads about greenhouses that were destroyed when one or two of the panels blew out, in a wind. If the wind is strong enough, it can then rush inside the structure and bend the soft aluminum frame so it's not salvageable. I suggest using extra clips (order them by calling the toll free HF number) and by using one or two screws in each panel, going into the aluminum frame. The above blog shows how we did that, too. Some people prefer to caulk their panels in place, but I never did because I like the ability to remove and replace the panels easily. So Goal One is to anchor the structure well, and Goal Two is to anchor the panels to the structure well. When we built our kit, the 10x12 was fairly new, and there were a lot of Gardenweb forum members building them. So, there were lots of us brainstorming solutions about how to strengthen the kit. I gathered many of the great ideas from this group and put them in our blog. I really suggest reading it, because I want you to have only happy adventures with your greenhouse! There are a number of modifications that will help it to be safer and stronger. None of them are expensive, they just take a bit of time. Treated wood is better than untreated for a foundation, especially if your climate has even average moisture. Some folks have even built masonry foundations for these greenhouses. It does need to be flat, though, as you'll have problems with the rest of the build if you don't get the foundation flat and the initial pieces put together in a way that is square and plumb. My advice is to take your time. If you need to, maybe consider asking a friend (or hiring one?) to help you with the foundation. I hope this helps a bit. Please feel free to post back, or contact me directly if I can be of more help!

The only reason not to do it is if you have critters that will eat the seeds. This is how I start the seeds for my hydroponic system (only using rockwool instead of peat), and this year I was puzzled because I was having such poor luck, with a large dead zone in the center of the tray, and only random seedlings around the outside. Then one night I was out there and discovered an enormous Cuban tree frog lounging happily on the nice damp sofa made by the rockwool, reaching all around to dig out everything at all spicy that I had planted and squashing all the poor just-up seedlings under the center area where he was lying. So yes, this is a good idea if you have some way to protect them, especially at night when everyone goes foraging. ETA Not the plastic, something like screening that will let the air circulate. I've thought about getting one of those metal screen covers for picnic food for next season.