Itsme,
I have a lean to I built on the south side of my house. It has 2 windows that are in a small office area that leads into the utility room. I can open the windows and with a small fan heat it from the heat out of the utility room. But once the sun comes out bright the heat builds fast. I don't have anything growing in it now so don't have the windows or vents open. My hi/low thermometer has recorded highs over 125 in the last 2 weeks. I'm going to order an exhaust fan and intake louvers. Will be the only way I will be able to control the heat this spring.I can control the heat in the cold frames a lot easier than I can the lean to. I know growers who keep a shade cloth over their small greenhouses even in the winter. They say that helps to hold the temps down and they don't need to run fans ect. But I decided to get the fan and louvers and then I won't have to worry. Jay

I have a 12' x 24' greenhouse that I am just starting to use. It has two doors I can open (with screens to keep the bugs out) and 4 large vents (with screens to keep the bugs out). I don't have shadecloth for it, but that will be corrected sometime in the next few days. WIthout shadecloth, good venting for air flow, a fan or evaporative cooler, etc., greenhouses get too hot here, even in the cool-season.

You can shade your greenhouse with shadecloth, and there also is a whitish greenhouse coating you can paint onto your greenhouse to reflect sunlight off of it. It is available from some companies that sell greenhouses and greenhouse supplies. You have to be careful with shading. If you shade too much, you keep too much light from reaching the plants.

I don't know of anything that could survive in a greenhouse in our summer heat, unless you use a combination of shadecloth or that white greenhouse paint-type coating, and utilize vents, and utilize something to keep up good air flow. I have a huge utility fan (it may blow everything right out the door of the greenhouse) and a big evaporative cooler, but I don't plan to have anything in the greenhouse in the hot summer months anyway.

Everyone around me who has a greenhouse keeps shadecloth on their greenhouse year-round.

Dawn

Itsme,

I had a lean to also about 8 years ago. I expect it was set up much like Jays. I had three windows all together in one bedroom and I set a box fan in the west window, closed the center window and opened the east window. The box fan would cool the greenhouse and help heat the house, but as it got warm enough to not want the extra heat in the house it became much harder to heat and cool the greenhouse. Even with the door open to the greenhouse it would still get very hot in the greenhouse.

I only used it part of one year because I was growing more food than I could use without it. It had no floor in it and the grass would grow like crazy in it.

Mine was a cheap structure of wood, pvc and visqueen. It was not practical for me to use it in the summer or winter because of heating and cooling cost, plus I was single at the time and one person can only eat so much.

If you don't have electricity to vent your greenhouse it will really be a challenge to keep it cool on a 100 degree day. I have had the itch to build another greenhouse, if I do, venting and shade cloth will be high on the priority list, and electricity will be a MUST.

Larry

I have 6x8 HF GH, see picture in below link. It have automatic vent openers and also used shade cloth during summer. Last year I used it from Winter to Fall. In the spring, it helped in hardening seedling and grow some topical herbs in the early spring. In summer, I tried few hot loving plants (cucumber, bitter melon, eggplants, herbs, etc), out of many trial plants only bitten melon produced heavily in the summer heat, some cucumbers. Indeed I did train half of the vines spread on the greenhouse roof, it served as additional shade-cloth and it gets some fresh air itself, that might helped it produce lot of fruits. I also used small heater during winter (Jan-Mar) when temp perdition were below 20. GH also house large water tub as heat-sync in the winter and act a pan-evaporator in summer. I also keep doors and vent open in the winter.

This small greenhouse is really useful in keeping the overgrow seedling in the large pot until transplanting. My seed starting rack not big to hold large seedling, greenhouse will there second home before to their permanent home in the ground. I also noticed that seeds germinated very fast if you keep trays in the greenhouse, then move them to indoor seed-starter light rack. By the way, this GH survived to large storms! My daughter's wooden play-set was trashed twice but this greenhouse has been intact, but one of the panel blown away during second storm. It was my mistake, not closed the door and went that time. I ordered that part from HF. I also reinforced that greenhouse panels with self-drilling screws, worked well in keeping panels intact in the strong winds. 6x8 GH is not high, just 6.5ft high which is almost equal to fence height, it also located next to fance and also planted deciduous trees front and backside of the GH to shade and also protect it from strong winds.

Dawn your GH is really Big!

-Chandra

Here is a link that might be useful: Greenhouse

Chandra, I think people with the small one like you have think they are OK, but the next size up has gotten some really bad reviews. I started to buy the other one when it was on sale and I had a coupon in addition, but after reading about them, I chickened out.

I was amazed last year after the storm to see that yours was still standing, but I think the fence must have played a large part in protecting it. Did they determine that you had a micro-blast, or what? Besides all of that hail, you had some real wind damage.

Our trees are all so large here that a wind like that would take out a house. I was in Utah on business one time and Al called to tell me that a strong wind had come through our neighborhood like that. They were standing in the street talking and saw a sheet of rain coming across the lake. Each ran into their own yard and Al made in inside the house. The across-the-street neighbor was on a golf cart so he just pulled inside his shop and waited a minute before going into the house. Al heard a big crash and a huge tree had gone into their house. Al and the man's son had both heard the tree hit the house and started running inside. The elderly neighbor was just standing their staring at the chair where he had planned to sit down. It had one of the huge limbs in it which had fallen all the way to the floor. He said he was lucky that he had been feeling 'neighborly' that day and had stopped to visit in the street.

It sounds like you have a good understanding of how well yours will work. That is amazing because a little greenhouse is normal very hard to control the temp in.

In the event that you ever decide to spend a winter at home rather than gallivanting all over the world, you could grow salad greens most, if not all, of the winter in there. (We should all have such an interesting job.)LOL

Thanks everyone for the info. I guess I'll try to locate some shadecloth. Can that be purchased locally or does it have to be ordered through the internet? What sun blocking percentage of shadecloth is best for OK?

I loved the little greenhouse so much I thought i might invest in an 8x12 or 12x16 kit. But now I'm just not sure it's worth spending that much money. Anybody with a kit have a recommendation? I have looked at the BC Greenhouses, Juliana, and the Victorian (an 8 x 12 can be purchased through Sams Club.) Thanks again!

Chandra, Mine sounds big, but it seem too small to me to do everything I want it to do. It is just a high tunnel greenhouse, with wood and PVC framing and 6 mm plastic greenhouse sheeting.

In the spring, I mostly will use it for seedlings that have outgrown the indoor light shelf but which cannot yet go into the ground. In fall and winter, I will grow cool-season crops in raised beds.

Before we even had this one finished, Tim was making plans for how we'll build the next one. My husband is a wise man because he figured out, even before I did, that one high tunnel wouldn't be enough for me.

Itsme, I am in southern OK and I see shadecloth in stores all the time. Some places sell it prepackaged as folded pieces in a rather flat package and others sell it on rolls. Some stores, and this usually includes Lowe's and Home Depot, have big rolls of it out in the Garden Center area and they'll cut it to whatever length you need.

Sam's Club usually has rolls of shade cloth in their stores in spring and summer, but I was in Sam's last week and they didn't have any in the store yet. The year I bought some at Sam's, I believe it was either 6' x 25' or 6' x 50'.

I've always wanted a big, beautiful greenhouse made of class or twinwall poly. Last year, during a tornado in our county, one family at the northern edge of our county had baseball-sized hail just demolish their glass greenhouse. A photo of it was in the local paper, and it looked so sad. That's why I have a high tunnel type---if hail destroys it, a new roll of greenhouse plastic is pretty cheap by comparison to replacing glass or twinwall poly.

One day last year our insurance guy stopped by our house for a few minutes, and while we were talking about the greenhouse he asked if I wanted to insure it. I told him no, but if I had a more expensive greenhouse I would have said yes.

Dawn