If you want to keep sunloving plants in it, you will have to take the plastic cover off. Even with shade cloth on it, it will get too hot for plants when the outdoor temp is 100. My greenhouse is glass and rigid polycarb so I don't try to keep anything in it over the summer even with all the windows open. Dawn and some others have film houses so they can tell you better what to expect.

It had a high UV rating, but It was relatively inexpensive, like $100 for a giant roll so I am not out too much if I only use it for one season, It comes with enough to wrap it 4 times probably. I figure with the May storms I might want to take it off to be less of a wind catch anyways. I should have used some rainx on the outside so the snow would slide off easier I think, haha. Do you guys buy ladybugs? I have something that just started nibbling little holes in my cabbage leaves and I want to eliminate them before it gets worse.. Plus in years back I have had serious issues with aphids. I just bought s1,500 but I only see them moving when it is hot.

I'd remove the plastic. If it is 6 mm, you should be able to store it and use it again in the fall/winter of 2014. If it is 4 mm or lighter, I don't know if it is worth hanging on to it to reuse it again.

I have 6mm greenhouse poly film on my greenhouse and it is covered with Aluminet Shade Cloth in the 50% class. Both stay on the greenhouse year-round. I don't even attempt to keep anything in my greenhouse after May (sometimes early May, sometimes later in May if weather is staying cooler than average). It gets too hot for most plants, even with 50% shade cloth, in winter and spring. To counter the heating caused by the greenhouse effect I open the two doors and 4 vents and run a fan as needed. I also have a large swamp cooler.

I'd like to suggest that you get a MIN-MAX thermometer and keep a log of your greenhouse's minimum and maximum temperature each day, alongside your area's high temperature and low temperature each day. That way, you can see at which point in the season your greenhouse is getting too hot. In my greenhouse, if I don't open the doors and windows by 9 am on a warm, sunny winter day, the temperature can hit 115 before you know it. By April? The temperature in there can reach 145 well before noon. You train yourself pretty quickly to open the doors and windows as early as you can every day because the greenhouse effect is very real.

The only plants I put in my greenhouse are those in containers, so I can move them out of it when the weather warms up. If you intend to grow plants in the ground within the greenhouse, you'll have to take the plastic off before the daytime highs get too hot in late spring.

Once I move all my plants outside in spring, I leave both doors and all 4 vents open all summer long so that the greenhouse isn't getting overly hot each day. Mostly I just store planting flats and containers in it during its off-season. In fall, I close it up a week or two before I intend to move containers filled with plants into it, and I am very careful to check it carefully every day for snakes. I normally am closing it up about the time that snakes are looking for a place to spend the winter, and I don't want for them to choose the greenhouse.

If your greenhouse doesn't have vents or at least two large doors or windows that allow good ventilation, you might want to think about adding them. Poor air flow combined with our typical heat and humidity can turn a greenhouse into a disease-infested mess. My long walls face the north and south to allow good lighting. My short walls, the end walls of the greenhouse so to speak, face east and west. Each of the end walls has a large walk-thru door and two large vents. Air flow is great, and I cannot think of a single time that the greenhouse plants have developed any kind of disease that could be blamed on poor air flow.

I love my greenhouse and it functions as expected, but I never intended for it to be in use year-round. Summertime here is just too brutally hot.

I can use greenhouse film for several seasons, but the only time I used construction plastic, it made it through one winter on the greenhouse and started breaking down before summer. I don't have a greenhouse now, but do use greenhouse film for low tunnels.

What is your minimum temperature goal? I have been shooting for 50 but have dropped down to 40 a few times without any losses so I wonder if I am heating too much?

It depends on what is in the greenhouse but I generally don't heat mine at all. I never planned to heat it, though I reserve the right to change my mind if we're still having weather like this in late March.

I do have a huge number of molasses feed tubs (they are roughly the same size as whiskey half-barrel planters) and cat litter buckets filled with water to serve as solar heat collectors. They line both the south wall and north wall of the greenhouse, sometimes two deep. I can lay boards across them and set flats of plants right on top of them. On cloudy nights when the wind chill is not too extreme, they can keep the greenhouse 10-15 degrees above freezing. They don't keep it quite as warm when there is a really severe wind chill. This winter, they have kept it at 32-33 degrees when the outdoor air temperatures have been as low as 18 degrees. Even when the outdoor air temp dropped to 5 to 8 degrees, just the water alone kept the greenhouse at or above 18 degrees.

I don't have anything in there at this time of the year that cannot handle zone 7 winter temperatures. When we built the greenhouse, it never was my intention to heat it all winter every winter. It is fairly large and I had no desire to run up our electricity bill by heating it. My greenhouse was only intended to give me a place to extend the season for a month or two in both spring and fall. It wasn't planned to be for full-time winter gardening.

Later in spring, usually sometime in March but also some years at the end of February, I start moving transplants I've raised from seed out to the greenhouse, including tomato transplants. Often I'll have 200-300 tomato transplants out there, and I don't heat the greenhouse. If I think the temperatures will drop below freezing, I just put a frost blanket rated to give 10-degrees of protection over all the tomato plants, and I do it in early afternoon to hold in whatever heat buildup the greenhouse has achieved. Between the large amount of water-filled containers that serve as solar collectors and the frost blankets, I have left tomato transplants out in the greenhouse when the outdoor temperatures have dropped to the low 20s, and the greenhouse temperature did not drop below freezing and the plants were not damaged.

If I was trying to keep tomato plants happy all winter, I'd try to keep the overnight temperatures at 50 or above. I grow a gazillion tomatoes in the warm season, but don't bother with them much in winter. To me, their flavor in winter is so poor compared to their flavor in summer that they aren't worth the trouble. It is easy for me to say that because I can tomatoes in many forms, freeze them and dehydrate them, so I can get my tomato fix all winter long, albeit not with fresh-from-the-garden tomatoes. The dehydrated ones, when rehydrated, are close enough in flavor to fresh ones that I don't feel the need to grow winter tomatoes. Most of the time, in the fall I will move a few tomato plants growing in molasses feed tubs into the greenhouse, usually in October, and sometimes not until November. I merely want to keep them warm enough that the fruit already on them can be harvested, and I can do that without a heater. Often, we are still harvesting tomatoes in December or January without even using a heater. If I didn't preserve so many tomatoes to eat in winter, I'd likely either heat the greenhouse or keep a couple of plants in containers in our sunroom.

You can let the greenhouse get a little colder than 50 degrees at night if your tomato plants aren't flowering and setting fruit and if your only goal at that point is to keep them alive throughout the winter or to keep them alive long enough to ripen and harvest whatever tomatoes are on the plants when they stop flowering and setting new fruit. The flavor of winter tomatoes can suffer in the greenhouse if they are exposed to too much cold temperatures. If you are letting the plants stay colder than 50 degrees, you won't get much fruit set. They need warm to hot temperatures to develop good flavor, and they need to stay above 50 degrees to set fruit well.

Pepper plants in a greenhouse are entirely different and I handle them differently. I don't put home-grown pepper transplants out into the greenhouse until it is staying well above 50 degrees at night without heaters. Pepper plants that are exposed to cold temperatures too early in their young lives can remain stunted and non-productive throughout the entire growing season, so I generally keep mine indoors about a month longer than the tomato transplants, and I don't put them into the ground as early as the tomato transplants unless it is an incredibly warm spring.

I have a space heater for the greenhouse, but never have used it. It is a "just in case" heater, in case we ever have an incredibly late cold spell after the greenhouse is filled with transplants in springtime. I'd probably use it if I thought the temperatures in the greenhouse were going to drop below about 20-22 degrees in spring.

I also should add that some people do not have much luck keeping their greenhouses warm enough with containers of water serving as solar collectors, but it works for me. I think two reasons it works as well as it does is that (1) I have a huge number of molasses feed tubs filled with water in there....probably about 35 or 40, and probably twice as many cat litter buckets as that. They literally cover the floor, so that all I have is a pathway down the middle aisle of the greenhouse; and (2) I deliberately chose Aluminet shade cloth because it reportedly would not only keep the greenhouse cooler during the sunny hours but also would keep it warmer during the non-sunny hours by helping hold in the heat that had built up inside the greenhouse. I have found that is exactly what it does. My greenhouse stays substantially warmer at night than a neighbor's greenhouse does. That neighbor doesn't use solar water collectors like I do and doesn't have Aluminet shade cloth. Together, both of those work well for me in terms of keeping the greenhouse as warm as it needs to be in order to keep me happy.

I also use my greenhouse for seedlings, because I don't get enough sun, or have enough room to keep them inside my house... This was my first year with a greenhouse and everything is an experiment so far, I may not always heat it. Where did you get your shade cloth and barrels? I assume that you have broccoli, cabbage, lettuce and spinach growing now? All with no heat? Do you sell your tomatoes or does it take 300 plants by the time you dehydrate, can, freeze, etc... I was thinking 50 would be enough but maybe I should start some more for summer... I am going to look up your threads, you seem to know what you are doing and that has been hard for me to find!