Sorry this may ramble a bit, but so much is going through my little head right now, I'm just letting it out as I think of it. This is bringing up lots of memories of when my dad started out with a small lean-to on the side of the house to sell tomato plants 35 years ago. That business grew several times until we had a single 40 X 50 greenhouse that took up the entire back yard. We now have 5 acres and multiple greenhouses at another location that I have run since 1997 and now produce and sell over 100,000 plants per season. So this is coming from a grower/retailer perspective. Check that you can sell items that aren't grown in your greenhouse. I have to grow 75% of what I sell on site in my zoning. Buy a greenhouse with the appropriate snow load/wind rating for your area. It doesn't take much wet snow to collapse a poorly designed greenhouse. I have two from a Canadian company-Harnois (the third is from a company that I think and hope are now out of business-they were awful to deal with). They were easy to put up and have worked great for us. The last one I bought (30 x 48-which probably the minimum you should consider) was about $7,000 nearly 10 years ago. This price included one heater and three roll up motors and two layers of plastic. I had to build my own end walls to save a little money but you can buy an endwall package separately. You will need electricity for the roll up vents (side and peak) and for the ignition for gas heater(s). But that requirement would be less than for exhaust fans for a ghs with no vents. I wouldn't risk my plants in somebody else's greenhouse that couldn't keep them heated if needed. Nor would I trust my hard work to a greenhouse made from PVC. You need one large enough that people can walk around comfortably and accommodate each vendor. Hoop houses generally don't have a lot of head room along the sides unless you get a high tunnel. If you expect the business to grow get a greenhouse that may be a little larger/wider than you think you need. Otherwise you will be replacing the small one real soon-kind of a waste of money. We went from lots of small greenhouses to a couple larger greenhouses to the single large house and now several large greenhouses. Buy something that is intended to be a greenhouse-you don't want to be jerry rigging something that might not work as expected. There are plenty of professional greenhouse manufacturers (Nexus, Atlas, Jaderloon, Conley, Harnois,etc) out there that will help you. They also will have the proper materials to use and be able to provide you with some guidance. You'll be much happier and the product will probably last a lot longer. Check out Greenhouse auction This is a past auction that still has 450,000 square feet of greenhouse left from a bankrupt nursery. They will arrange shipping for a fee. My hoop houses (20 x 48 & 17 x 48) are open at one end where I can pull the plastic up or lower it to get air and cool off the house. The other end has a regular sized door. The larger one is made so I can pull up the sides about 2 feet off the ground using ropes. Even when fully open, they get 100F + by late May or about 20-30ºF warmer than outside. I use these to hold plants-no customers allowed. Trust me, nobody wants to stay in those conditions for very long-customers or vendors. I also would be leery of the pest issue. Even if everyone has 100% pest free plants (extremely unlikely IMHO) you will get pests. Who will be responsible, and what kind of controls will you use? Preventative or curative? An ornamental grower will have different requirements than an a veggie or herb grower. You may have to have separate greenhouses and spray equipment etc. This idea opens you up to additional liability. If somebody else's plants are lost in your facility you'd better have insurance! Of course you should have insurance if the public will be on your property anyway (a hidden cost and a selling point to potential vendors) $25,000 is not a lot of money. You will run into lots of unexpected costs. Will you have to make other improvements to accommodate the public and vendors-like bathroom facilities? How quickly do you expect to get a return on your money? The people who you should listen to as far as the type of structure are the people who would be using it. What are their needs and concerns? Taking the plastic off in the winter raises a few comments/questions. I assume that you would recover in the late winter/early spring. I don't know about your area but in mine that time of the year is the worst time to try to stretch a huge piece of plastic because most days are breezy. It takes only the slightest breeze to fill a greenhouse cover like a giant sail. You have to do the job when there is no breeze otherwise, you will be miserable trying. It is also a job for several people. The larger the greenhouse the harder it is to cover. Although easier to cover a small greenhouse heats up extremely quickly and has other disadvantages as well. $10 a day is a lot to pay for a vendor-farmers markets in our area cost $50 for the whole season (May thru November, one day per week). Maybe you should charge for the whole season instead of by the day. Or do both but give a discount if they pay for the whole season up front. That gives them an additional incentive to show up everyday. You have to convince your vendors that you have something to offer for their money. And it needs to be something they can't do on their own and will make them money. Find out what they expect and need and then offer that to them. What would the advantage be to have their plants in your greenhouse if they have their own already. Is this advantage worth them paying a little extra money to you? Who will take care of promoting the market? Pay for advertising? Hope this helps!

use rope that is attached to the baseboard and the board the poly is attached to in a zig-zag pattern. if you want to use less rope you can just have vertical pieces of rope every few feet attached to the baseboard and the board the poly is attached to. there are many pictures available if you google roll up sides.

My hoophouse is pvc but I still utilize roll up side walls. I have 1.25" pvc pipe as my roller if you will. The poly is taped in a couple spots and rolled up about a foot or so before it leaves ground level. I just drilled holes through the poly and pvc pipe and use three inch long sheet rock screws to join it to my base board. If its calm, no wind I'll just put three screws in for the night. Otherwise I batten it right down every four feet. Your Situation my be different (metal pipe/heavy) but I'd design several u shaped channels for the pipe to rest inside of in the closed position. Place one every four ft or so to get a good seal and design a quick clamp or just screw or lag bolt it for the winter. I would not bury anything in the frozen ground! Also, some commercial growers use 2x2" joined with metal as the roller and simply attach it to the base board everynight with two headed nails. Very simple. There is always the what if factor! Hope this makes sense to you.

Thanks for the listserve info Flowerfarmer. I started with a high 20x96 high tunnel in 2001 growing tomatoes and cucumbers. It was a revelation for me although my season was ended when the plants cooked in my absense(at market) in Oct of that year. So I modified the structure by bringing in electric to include a thermostaticly controlled exhaust fan and intake louver, circulation fans, stoker coal stove and lights. Now I can plant in early March and have tomatoes in early June. It's now a greenhouse. In 2004 I was able to purchase a used 30x96 structure and I immediately ran electric to it and installed an exhaust fan and lights. Other than a second exhaust fan given to me and an intake louver I bought at an auction, I probably will not install anything else in it. I typically don't plant in it until early April but it has convinced me to stop planting tomatoes in the field. As far as definition goes the high tunnel would not have the electricity or heat features of a greenhouse. I've heard that some growers use that term to describe a portable structure to avoid paying higher property taxes. For me, I am not in such an area and the cheap improvements with mostly used supplies has doubled the extent of my harvest season with much improved fruit quality. Both of these structures have the rollup sides becuuse the exhaust fans can't remove the summer heat near fast enough. I usually leave the sides in the rolled up position continuously from june thru Sept. anless bad weather threatens. I've tried peppers with poor success mainly because of light availability when peppers are grown with vertically growing tomatoes(clipped to frame suspended stringline) and cucumbers( trained onto frame suspended plastic mesh). I might try peppers again in a future tunnel). I have a small 15x40 bench greenhouse that I use for the potted plants- probably what you are looking for. You can erect one for under $1000 if you avoid all the frills. My frame cost $400 in 1994. I put a dubble poly plastic covering over it and haven't replaced it yet. It has a $3 used barn fan as an exhaust fan and a woodstove for heat. The benches are hand made stands covered with old doors and plywood covered with plastic. By April it is packed with plants, most of which we start in our house under lights. Sorry for the rambling but I wanted to paint a picture of SEASON EXTENSION as it works for me. June tomatoes pay for my structure costs repeatedly each year. By mid july everybody has them.