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!

24 X 30 is not a standard commercially sized g'house but should be a nice sized one for your purposes. If you are serious about conserving heat, you may wish to look into a pit-style greenhouse. I have one g'house we earth dammed into a hillside on its north side and it is by far my most efficient one. It was the first one we erected, and still my fav for growing and I keep this one fired all winter in a colder zone than you and it's cheaper to heat than the smaller one next to it. Actually a heavier double layer poly film with air inflation is as insulative as a thinner twin walled polycarb. If you are off the grid, you can get out of using electrically dependent fans by using roll siding. Big greenhouse fans are a heavy electrical user. This would be an issue with wind and solar power. The new top vent designs are also something you might want to look into. A grower up the road has these and it seems to be working for him quite well. I use a variety of systems depending on what I am growing in which house. There is absolutely no reason for you to be running your g'house in summer months. You will not be able to cool it down enough without some major equipment to produce a vegetable product as healthy as one grown outdoors. Let God and nature take care of that one. Use it for season extension. You can literally write books (heck libraries) of advice on setting up a first greenhouse but what you do now shall impact the success of your project down the road, so choose carefully and keep your expectations realistic. I've been operating g'houses for 25 years now and I had to still ask a lot of questions for each house we erected and it takes awhile to get to know what you can demand from them and at what expense. I'm putting a good link below with some very basic information you might find helpful. Good luck and good growing. Here is a link that might be useful: greenhouse buying guide

The roses are grown for cut flowers and are sold to retail florists. They have to cut them in the bud stage, so they cut roses several times a day. The plants aren't for sale. Wish some of the new ones I saw were. I don't know anything else about the rootstock. Maybe some one else can answer any questions you have. Yes the hydrangeas came from them, plus other cut flowers that they sell to florists. I wish I could have stayed longer just at this nursery. California pajarosa

I'm in Saskatchewan Canada so probably even slightly colder than where you are but it is super sunny year round here. This is my first year growing the superhots with a combo of starting seeds inside under grow lights, then moving them to a greenhouse with heat for spring and then fully outside for summer. They are now back in the greenhouse with no heat as nights are getting cold and am just starting to see the superhots ripen now and they were started in Feb! So that's 8 months and just starting to ripen! So you may want to go with shorter season varieties. A commercial pepper guy at my farmers market also grows some super hots in a heated greenhouse and he uses CO2 to force ripening so that may speed things up. I think the cost of all the heat and light etc for your climate will be pretty cost prohibitive but that's just my opinion.