Opinions on where to put Greenhouse, please!

Hello! We want to get a lean-to greenhouse but aren't sure what place would be best. There is plenty of wasted space on the south side of the house, where there is a large concrete slab. I have read that a southern exposure is good for a greenhouse. This spot would get sun hitting it all day, and beating down on it for several hours midday. (The bedroom on that side of the house is the warmest room in the house.) So, I am worried that it would get too hot. To add to that worry, I have talked with a gardener friend of mine that used to have a green house that sat on a concrete slab, and even though she had a shadecloth and an automatic fan and vent, she said it was so hot inside the greenhouse, all the plants suffered. She said that was the most unsuccessful greenhouse she ever had. Does anyone have an opinion about this?
The only other place we could put a greenhouse is on the east side of the house - it wouldn't get nearly as much direct sun, but would it get enough sun?

During what seasons do you anticipate using the greenhouse? If it's just going to be a place to overwinter tropicals or get seeds started in late winter/early spring then the south side is probably best, but if you're planning to use it year-round then the east side might help with the cooling...but you do need to be careful that you'd be getting enough sun over there for whatever plants you're trying to grow.

Oh, good point - I use mine in the winter only, to overwinter plants and start seeds.

south side would be great during winter. and if you have room some solar mass would help with the heat during the night. "whitebear"

Not to mention that on the south side that it would probably be protected from the wind. Maybe budget for a thermostat controlled vent fan that turns on when it gets too hot. I found one at Lowe's for about $40, it is labeled "window fan" but would work over your vent, assuming you have access to electricity.

Go with the south side.

Ok, so what about the concrete pad? Will the plants get too hot?

the concrete pad will act like a heat sink for storing heat for nightly warming. the only thing is make sure you vent it well. and misters will help cool if its in the budget.

The large greenhouse near me has a concrete floor. In the summer they spread mulch on it, but in the winter it is kept swept. We are putting up a 8x8 greenhouse on a slab and I'm not worried since I will have plenty of vents.

Erica, where you are, you have the right idea. I know your weather well. I am about 60 miles from you. South side with concrete slab for winter housing of your plants is perfect. You will still need a source of heat in January and February for sure and possibly much of December.

Ok, makes sense! Maybe that concrete slab will save us some $$ with our heating costs.

If you build it around a window it can be a passive solar heater for your home. You open the house window and when the furnace comes on, it distributes the greenhouse heat to the other rooms. The greenhouse would naturally vent warmth into the house since the house air would be cooler. It would only work on a sunny day and between the hours of 10AM - 3PM. The greenhouse could end up paying for itself and then some.

I, too, am wrestling with location for my GH. This will be my first GH (bought the Rion Silverline 6x8), and the last thing I want to do is get it set up and secured, only to kill my plants and have to move it due to overexposure. I plan to use the greenhouse to keep my tropical plants safe in the winter, as well as whatever I can do in it during the summer months (display some plants, potting of new plants, etc). At night time (crazy at this might sound), I expect it to add a level of ambiance to our back yard/entertaining space, as the panels are pretty beveled polycarb, and I can imagine soft lights in there illuminating the immediate/surrounding area.

My options are all south facing.

1) On concrete slab with some shade in summer from overhead deciduous tree branches (so the winters will be mostly exposed to sun).

2) On ground a little further out by my deck. Very little shade in summer.

3) On the ground in a far corner of my yard, completely exposed to sun all year long.

4) Add on to my existing deck and place on that for foundation, offering a little shade in the summer.

I would appreciate feedback from GH owners about the pros and cons of concrete slab foundation vs. on the ground. Also, and this might seem like a silly question, but I'm a newbie so I guess it's fitting, if I go with a ground foundation/location, do I need to build up the "floor" aside from a vapor barrier and pea gravel? I've seen pictures of some with wood floors, and wasn't sure if that is better to do. Any/all feedback/suggestions/links to GH-erection for dummies like me is greatly appreciated! :)

I chose to put mine on an existing concrete slab under a deciduous tree. If you have it in full sun in the summer, you will need a shade cloth.

I have put solar lighting in my small GH, I like the look at night. They are small lights, not so much that you can work in there but just a soft glow.

Cathy -- I read about the concrete adding to the heat in the summer (though I would think the semi-shade during peak hours would help offset that some). Any trouble with that in your set-up?

Consequently, I also read about that same slab holding in heat for the winter being helpful in terms of keeping it warm then. Any comments on that in your experience?

Thanks much!

This message was edited Mar 17, 2009 10:28 PM

I've not gone through the summer yet. I took my cue from a local big greenhouse. They put mulch down in the summer over the concrete. I'm going to do that if it seems too warm, but with the vents and windows open today in full sun and 80º, the temp didn't go over 80º. I wanted the heat retention in the winter, a bigger concern for me. Running a fan is cheaper than running a heater.

Ours will be a lean to type against the house on a south facing wall. Part of the floor will be brick and a brick back wall to help catch the heat. There will be a door way between the house and GH and also the kitchen window. Both of which could be left open or closed to add heat. We have a solar house and have picked up a few ideas for solar heating of the GH, too. You can paint your concrete floor a dark color to absorb more heat but be a bit careful as wet painted concrete floors can be slippy. Cooling in the summer can really be an issue. You can do several things to reduce the light/heat in the summer. Such as shade cloths and sprays some homemade like white wash & powdered milk some commercially made to help with summer overheating. I understand that the lime based white wash is only to be used on glass GH as it is bad for the poly panels. Good luck with you GH project please post a few pics, too.

Hi Cathy,

If I were you, I would get the automatic window vent openers for your vents. I have two. One for each set of vents in the roof. You do not need electricity. The heat melts the wax which expands and opens the vents. Before I got them, I killed some plants. You will go crazy trying to remember when to open and close the greenhouse. Even if you don't open the door, the heat will rise out the top of the greenhouse. I am from New England and it is pretty hot even during the summer. My greenhouse is attached to my house (not lean to). I heat it with the wood stove in our family room which is the room the greenhouse is attached to. The trees semi-shade my greenhouse in the summer which is great. Hope any of this helps.

Bonnie

Thanks Bonnie, I bought one, it wasn't enough, so I've ordered another vent window with opener, and an opener for the back louvre window. You are right, I was going nuts running in and out, and the day I got stuck at the doctor's office longer than expected, it got HOT in there even with the vent open all the way. Now I'm trying to get the auto vent to close sooner, it opens just fine but waits too long to close. I've read that having more than one vent will work better, I sure hope so. The tomatoes love it hot, but the lettuce looked a little wilted. If it wasn't still dropping into the 20's at night, I'd stick the lettuce outside. Maybe next week.

Wow, I thought Missouri was warmer then New England. We haven't dropped below 35 degrees for a week or so. I was thinking of putting my first lettuce out this week. Broccoli will go to. Do you know if kale can go out also?

If the auto vent isn't working well, it is probably because you have to put the wax container away from the vent as much as possible. When I first put mine in, it would open because the greenhouse was over 80 degrees, but then would close because it was cooler outside. My husband adjusted it after talking to the manufacturer and it works great now.

Wish I could say that we have not dropped below 55. There was snow on the ground when I woke up this morning. It was not much but it was still snow! Nights for the next few days will be in the mid 20's. I am in south central Missouri and spring weather is unpredictable and unreliable. It can be almost 80 one day and highs in the 40's the next. Almost 80 was last week and 40 is today. It is not a good place to be watching baby sproutlets.
I would think that kale can go in the ground now. Mine is planted.

What about onions & garlic?

Definitely onlions and garlic need to be in the ground. There is an old saying that a snow after the onions are planted makes the onions sweeter. That shows you they will not be hurt by a little cold snap. Garlic is a tough little thing and can handle most of what nature throws it.

I think the opener problem may be how fast our temps have been dropping in the afternoon. Kale is like cabbage, it likes cold.

Bonnie that is a very pretty GH, did you build it yourself or from a kit?
Re temps. We've had a bit of a drop in temps down here in Pa., hitting low 30's and high 20's this week at night. Not bad during the day though.

Hi Holly Ann,

My husband built it from a kit. It took about two days. As you could see, building on ground level would have been easier, but I wanted to attach it. It is so wonderful to be able to "visit" the greenhouse all year and just through a door. We bought it from http://cedarbuilt.homestead.com/. It is a company in Vancouver, Canada.

I quickly have been outgrowing it, so we purchased a sunshed (cedar as well). The shed has only poly ceilings. As pretty as it is, it's insulating factor is 0. I am going to have to place a layer of plywood, then place bricks for the floor. I learned from some others on this site that the bricks hold the heat during the day and release it at night! The sides of the shed are thin boards of cedar overlapped. Again, I am going to need to put some kind of siding on the inside walls. After that, I think it will be fine to put plants in it as early as March.

Bonnie

Thanks Bonnie, Ric and I have been planing a GH for years and are finally ready. Ours will be a lean to type against the back (south) wall of the house and a door will go right out from the dining area. We have large glass windows stored in the barn to use and now are debating weather to use glass or not. It's a terrible hard decision as I had pictured exactly what my GH would look like, but know how hard it will be to heat. So many better products are now available. Mine will be more like a tropical conservatory so heating and cooling is even more of an issue as I will have plants in it all year round, and will want my temps a bit higher in the winter than some keep theirs. I very much like the look of yours and will check out that website.

Thanks for the info about the onions, garlic, and kale. I learned from an older member of our garden club that planting garlic near rose bushes will scare away the japanese beetles. I think it is worth a try. What do you think?

Bonnie