I'm not familiar with your growing zone, the amount of daylight or ambient temperatures for your area, but I can say that a hoophouse type structure makes a tremendous difference in retaining temperature and humidity for growing things.

In the winter up here in Wyoming, we can get in the 70s inside the greenhouses when it is in the teens outside. That's just using the daylight - no heaters.

We're growing turnips, lettuce, Swiss chard and kale now, even though our temperatures at night have dropped into the low 20s. And, we use no additional heat - we just use a row cover inside the greenhose to serve as a greenhouse inside a greenhouse.

I suspect the problem that you will have is too much heat inside the hoophouse instead of not enough heat to support your interests.

The link below is to a simple PVC greenhouse. You can also build something similar by making "ribs" or "hoops" and creating a hoophouse style greenhouse.

Up here in Wyoming where we are dry in the summer and windy and very cold in the winter, the difference in plant growth between indoors and outdoors makes it almost essential to have a greenhouse if you are going to be serious about gardening and keeping plants from drying out or being frozen and wind burned.

Here is a link that might be useful: Build a PVC greenhouse

I live in Birmingham. I keep a cool greenhouse. I only heat when temps are predicted for 35* or colder. The ground in the south stays relatively warm all winter. A hoop house without heat can protect from cold damage down to about 28*. My greenhouse stays 8*-10* warmer inside than outside without heaters at night. I suggest you use a double coating of plastic with dead space in between. YOu may need a little heat if it gets down into the twentys or teens. A 10K or 20K BTU kerosene heater will keep plants from freezing.

Thanks !!

i have a hoop house that is heated, my first year, but I live in North carolina also. I live north of winston-salem. I can tell you that during the day it will get warm and you will probably need ventilation. However, if the sun is not out it is normally 8-10 degrees above the outside temp. I have a 14x35 and before I started the heater it got down to 46 inside with outside temps at 37. I do have additional insulation and I used double poly 6ml with a blower. I guess it does depend on what you want to start in january. I would highly recommend a heat source if starting this early. In our case, we used the hoop frame, ordered plastic from farmtek, you will need ventilation fans and circulating fans. We anchored with steel rods and used treated wood as foundation. We also used polycarb boards and extra insulation. We also have a blower in between the plastic for extra insulation. I guess it all really depends on your goal. I am having humidity issues, but will try some advise found on this site. Good luck maybe I can help with some of your questions. That is the great thing about this site, you can help others, while still needing help yourself.

I erect a simple hoop house in my garden for the winter. I made mine out of an old 10 by 20 foot canopy frame (metal) with extra cross pieces and braces made of pvc pipe. It is all very homemade and crude but it works like a charm. I don't go for all the fancy stuff because I am only storing large potted plants in it instead of trying to grow a crop. I don't even have doors on it, I just bundle up the extra plastic sheeting on the two ends and clamp it all shut with large plastic clamps at night and open them up during the day (unless it stays cold). I live outside Raleigh. Occassionaly I have a mild frost inside the hoophouse but most of what I am growing is dormant by late winter anyway so I have rarely lost a plant. I heat with a small electric space heater on most nights and if its going to get into the low 20's I drag in a kerosene heater and let it run all night (it usually makes it too hot!). If the temps are supposed to dip into the single digits I cover the whole thing with an extra large fabric tarp and run both heaters (I've only had to do this once in the 8 years I've lived here). Many plants are sensitive to the ethylene gas given off by the kerosene heater but I haven't had a problem - and I collect impatiens which are very sensitive to it.

I imagine if you wanted to grow a food crop you would need to build it sturdier and have it heated better and probably install some lights. Most of the tomatoes or peppers I have tried didn't get growing strong enough to produce a crop in mine. I mostly store large citrus, tree ferns and other potted tropicals that can actually take a light frost.

Most people that see it are impressed with the easy construction of my hoophouse - I use no power tools to set it up, everything is held together with duct tape and clamps. But my yard is sheltered from strong winds and I haven't had much snow so it hasn't gone through much winter weather.

It all depends on what you want to grow.

Good info here folks. I'm looking at putting up a hoop house myself. I want a good sized greenhouse for some growing veggies, some tropical overwinter and general winter protection for some of my more tender potted plants. I have been looking at the "hard" poly carb greenhouse kits, but for the size I want, the are a bit out of my range. I'm looking for a 12 X 15 or a little larger one. I've been considering the Quonset hut style but really like the one in the link above. My question is if I choose to go with the Quonset hut structure, how hard is it to bend the PVC?? Do you construct these on a summer day? Or do you heat the PVC to bend? This is looking to be the most economical way to put in the size I want. Thoughts on design as to which is easier to construct and best for use?

If you build a PVC hoopbuilding, it is very easy. You do not need to heat the PVC. It will bend in a Quonset shape by just firmly placing one end in the ground or attaching it to the side of the greenhouse frame, grab the other end and bend.

I would also suggest that you that you use 20 foot pieces. Take my advice, don't try to put to ten footers together. I had many problems and failures with the couplers and tee's

Search for hoophouse and jrslick. I posted some directions on Gardenweb.

Good Luck!

Before I got the old canopy tent metal frame I built my hoophouse completely out of pvc pipe - a very easy material to work with. Mine is 16 feet wide and 20 feet long, an arch of 28 feet with a ceiling of maybe 8 feet. I built mine in a quanset hut shape of arched ribs that would come apart and be easier to store (I disassemble my entire hoophouse and store it over the summer). Jrslick is right in that you cannot get a good connection using regular "T's" or couplers made for pvc, what I did was run a short length of wooden dowel rod (2 foot long) inside the pipe at the junctions. I blocked the dowel from sliding down the first pipe by screwing a small wood screw into the pvc one foot down from the junction. It is far easier to assemble the ribs flat on the ground and then raise them into place as one long pipe. Pvc will bend easily if it is long lengths. I found that if I pound the short "U" posts into the ground along the outside edge every 2 feet or so, I can lay the pipe into the "u" and secure it with either duct tape or zip ties or screws, or all of the above. I use landscape fabric staples (those big wire thingys you pound into the ground to hold landscape fabric in place) to secure the plastic sheeting to the ground around the frame. I used to build complex doors or use old screen doors as my doors but now I just use large clamps to secure the plastic to the ribs along the two ends. I got some tarp zippers and made zipper doors on both ends. So far they work like a charm. The one condition that sets me apart from everyone else I know using a hoophouse around here is that I have to do all this work by myself. I can usually set up the frame in one afternoon and pull and secure the plastic sheeting in another. If I had one other person available to help I could probably get it all done in one day (pulling a 30' by 50' sheet of plastic is the hardest part - made easier if it is a windy day).

I read the book recommended here somewhere by Eliot Coleman. He says that if people knew how great a hoophouse was, every gardner would have one.
I plan on getting one up this spring. I think I'm using cattle panels to frame mine w/6ml.

We just built a PVC hoop house that is about 22 feet wide and 65 feet in length out of 1 1/2" schedule 40 pipe. We bought 20' joints of bell end pipe and cut some of them in thirds (80"). We put an 80" piece to a full 20 foot joint without using any glue. To hold them in place, we drove the shortest metal T-post along each side at an angle and then with one on each end of the put together pipes we simply pushed the pipe into an arch and slipped it over the posts. It is much easier to do this if you grind the corners off the top of the post before driving it in the ground. Otherwise, the corners want to scrape the inside of the pipe. After all the arches were in place, we installed boards along each side and one on top for the ridge. The boards were attached using metal pipe clamps screwed to the boards. I bent the clamps out a little before attaching so that when they were screwed down they would clamp tight to the PVC pipe. Then we pulled a 28' plastic cover over the frame and secured it with tape and staples. We get some wind sometimes so I am going to add wind bracing on the inside yet. We had no problem bending the pipe to fit and will probably build another unit 96 feet long in the next month. This was built over several beds of already half grown cool weather crops and we are going to seed others in the extra space.