Well, I need a lot of space, because I'll probably never stop building perennial beds here. I though about the hoop, but I was worried that it wouldn't be warm enough for an Indiana March. I'm not just growing winter sow perennials, but many other, plus some veggies too. I figure I at least need grow lights...but still researching! :)

I have been pursuing a similar goal, I sowed twenty 1020 deep plug trays with perennial seeds this year. I am more interested in letting nature cold stratify my seeds, similar to the wintersowing method, and haven't been aiming for the extra warmth and an early start like a greenhouse. I tried a low tunnel type setup with row cover fabric the last 2 seasons.

There are strategies to grow year round in a greenhouse passively without added lights or heat. One way is to orient the tunnel east to west, and place a radient barrier similar to mylar on the north half, to contain the heat somewhat at night. There are passive automatic vent openers too. Research "solar passive greenhouse". Lots of options for active, powered greenhouse, beside heaters, running 2 layers of plastic and an inflation fan between the layers creates an insulating air cushion. Bootstrap farmer has lots of videos on youtube for info. High tunnels are very scalable and there is plenty of University advice published as well.

Rain control has been an overlooked problem for me using row cover fabric, trays flood, seeds wash out, and seedlings drown, so I will be switching to greenhouse plastic with lots of screened vents next year, still aiming for natural cold stratification. Look out for slugs too. I currently have a 4'x12', 2x6" wood framed bed with 1/2" PVC hoops attached, but a wider walk-in high tunnel would be easier to work with and a better place to start. You could build it makeshift from PVC conduit (conduit is UV resistant unlike Sched 40 DWV PVC) or steel arches, steel would be more durable and the parts to work with it are commercially available, so you wouldn't be repurposing things. You can more easily attach wooden boards and wiggle wire to steel arches. Cattle panel greenhouses are also popular for a more budget friendly makeshift option.

My initial observation was that you said you had space in an unheated garage. I was concerned about the temperature. As you said with the hoop the heat was your concern too. There are a couple of ways to take care of this depending on your plants requirements. You can use a propagation mat under your seedling trays in your garage. Also, you could build a "cold frame" of sorts over the area in your garage. Double up, like dressing in layers in the winter. For a cold frame you can place heat cables under your soil to heat things up in there. Also, you can throw a heavy blanket or something with an insulating effect over the cold frame at night. You would need lights in your garage, you would not need lights in the cold frame. To start seedlings in a greenhouse you would probably not need lights. Mostly those are used in areas where there either isn't enough light or there isn't enough light for a long enough period of time during the day. This is mostly for mature plants. You can get a greenhouse with roof vents and/or side vents and try that. A lot of the greenhouse kits have ventilation at their doors as well - either a Dutch Door or a glass that can be raised to expose screen. Depending on your weather and sun intensity, and how long you intend to leave the plants in the greenhouse, you may be able to get away with just that. If that is not sufficient you can retrofit a ventilation package as the need comes up. Tammy

How many flats do you want to work with? If you only do a dozen or so, smaller stuff like cold frames or hoops or setting up a heated space in the garage with lights might serve you better than a greenhouse. If you do a few dozen, then a house might be better for your needs. Or if you are in the habit of potting up your plants from small cells to bigger 3" and up pots to grow out you may need greenhouse space.

You may also find you want an outdoor nursery area with your greenhouse. You say you aren't interested in overwintering but... Some perennials can benefit from being container grown up to a bigger size than what one seasons growth provides. Or you get something you want to grow out a bit before putting in the yard.

I feel ya with the 5 1/2 acres. I have a lot of land too that I'm working on with perennials. I started out with just a few flats of annuals originally, mostly veggies and some flowers. Now I've gotten to the point of getting past that dozen or so flats of all the stuff and need to work on getting a greenhouse of my own set up.

Great information! I definitely plan on having a few dozen - or more! - flats every year, for early-starting veggies, annuals, and perennials. Probably too much for my garage.

I haven't considered a hoop house. So a hoop house sits on bare dirt but provides insulation/protection for young plants, that are planted directly into the ground (if I'm understanding this properly)...and can be protected during a cold snap with protective plastic and having the hoop house properly oriented...? So I could start seeds, in the ground, in early March, and they'd likely get enough sun (through the plastic?) and heat (insulation if needed) to thrive? I will check out Bootstrap Farmer and do a little more reading.

Just to clarify...living in southcentral Indiana/zone 6a/6b...if I do buy a greenhouse and start flats of seeds with heat mats early in the year...I will probably NOT need grow lights? They'll get enough light from the sun? And if we have, for example, several dark days of rain, they'll still probably be all right without grow lights? That's a major factor in my decision.

Thanks so much for the feedback and I'll keep doing research!

beesneeds, it's SO tempting with all of this 'blank' land! I've already added a 10' x 12' bed in front of the house, and bought a TON of starter perennials at local sales. I'm planning to propagate this original group, always adding in more (of course!), and just keep building beds. I love it so much!

You don't have to plant in ground in a hoop house. Some folks do, some have raised beds set up in them. Some folks set up racks and do their flats and bigger gallons pots in them. Some folks set them up fairly low to the beds, others with much higher side walls before hitting the dome.

I've seen pretty basic ones of just some bent pipe with plastic attached and a flap over entrance all the way up to professional structure, double walls with air flow for heating and cooling... Depends on how much cash and how much greenhouse you want.

Oh, and can have. Make sure you check with your local building person at the town hall to find out what ordinances there may be about greenhouses for you. You probably can have a simple hoop house, or be able to build X footage of greenhouse in general based off the size of your property, what kind of greenhouse you want, and so on.

I might have gotten my terms mixed up, a hoop house is used interchangeably with low tunnel and high tunnel. The low tunnel is the mini green house over a row or bed, and high tunnel greenhouse is the larger walk-in type that can be designed to pretty much any spec. I edited my last post to reflect that.

Naw, it's probably me Skip. Around here hoop house is kind of anything that's hoops, big or small, so long as a person can get around in it, lol. And the covering seems to count too, hoop houses have the more flexible plastic films or shade cloths. For some reason the few folks around here that have the rare solid panel hoop houses tend call them huts.

Greenhouses tend to be the more square built things with windows or panels, lol.

Heh, I've had a bit of fun with some sort of greenhouse stuff over the last few years. I've long used a handful of those little 4-shelf mini-greenhouses. I love them. One year later on in the season I spied a decent 6x8 or maybe 8x10 "pop-up" greenhouse on clearance and thought it would be nice to have a real space set up in the spring to move around in! As a test to see how it set up, I popped it up over my pepper patch as a season extender into the fall. Boy did it work really nice for a few weeks, peppers were still happy while the garden outside the greenhouse bit the frost... till one stormy night when Mother Nature managed to break the tethers on that greenhouse! We found it the next day. It had apparently puffed up and over the fence, cleared the brush line on the back of the neighbors yard, and landed a goodly ways into the field behind that. It was really funny when I asked my neighbor if he had seen a greenhouse laying around anywhere, and he asked Why? Did we lose one?

The next year in the fall we wrapped the old dog kennel framework that I use for gardening anyway in heavy duty clear plastic and tarped the roof with white tarps. That worked extremely well for overwintering and a spring greenhouse, I was able to bump my flats outside way earlier than usual. But we hadn't but enough thought into support for those tarps on the roof, and we had serious sagging problems- ended up solving the watering need in the greenhouse but... wellll... ;/

Last spring the neighbor whos been in contracting his whole life is kind of getting into retirement and got a lot of stuff piled up in the barn, including a bunch of windows. He told me I could just have them all since he can't really use them and they are just sitting and he can tell I'm wanting to have some sort of greenhouse or something for all the gardening stuff I do around here. Some are probably good for greenhouse, some will probably end up becoming lids for raised beds to make for some cold frame action in the future.

That's one of the complaints I've heard about the cheaper greenhouses, that they're flimsy and don't stand up to a strong wind! Great idea to use plastic over the dog kennel frame. YEARS ago I got a truckload of old glass windows on freecycle. I stored them at my grandparents', planning to nail them together "somehow" to make some kind of a greenhouse. Flood came along and washed them all away, though! Oh, well! I'll try to think creatively about ways to make this transition work. I have to admit that I'm really attracted to the look and relative "ease" of a greenhouse...but if I can make a high tunnel hoop house for a fraction of the cost that basically does the same thing, that's what I'm going to do! Really excited about the possibilities!

I got my 8x12 greenhouse on freecycle. I love it to bits. I raise all my own plants from seed, sowing pretty much every month of the year apart from July. It was the best thing in my whole gardening career - I can grow enough plants for my garden, my allotment and even for my wood. The advantages are numerous although I don't heat mine, nor bother with heating mats, propagators or lights. It is at its fullest over winter, almost empty apart from scented leaf pelargoniums, a passion vine and bell peppers.

Instead of a cold frame would you consider a hot frame. It's basically the same thing with a manure source of heat. Some techie types might say you need electric heat, but you don't.

You build a frame from 2x12's to match the size of a window you find used. In the spring you dig out the ground under the hot frame 3 feet deep. You fill it half way with manure and then raise the soil level to about the original level. Fresh manure works better than well composted manure most gardeners use. Manure with straw heats better than without, if there's none in the manure you can add in layers of spoiled straw or old garden mulch straw.

The following spring you repeat the above except that you have some "well composted manure" to improve your garden beds.

It helps if you're retired as no matter what time it is when you need to open or close the glass you have to open the glass. There are thermostats to do it automatically, but I have no experience with them.

I grow annuals, some perennials, herbs, and veggies in cell packs inserts and flats. Most of them are in the 32 per flat size, some with fewer cells (bigger plants). I have three grower plant stands with wheels, four adjustable shelves each (with lights), with room for a total of sixteen flats per unit.

I start my seeds in two or three germination flats over heat mats and transplant everything into the cell packs, no heat, under lights. We constructed removable frames for each cart with aluminum insulation panels which help reflect light and heat all winter long in our unheated garage! The frames can be unscrewed in a few minutes to store in the shed at the end of the season.

So, I end up with a average of around 1,800 plants between the three carts! During nice days, the carts can easily be wheeled out into the back yard for "some fresh air and sunshine" and a bit of rain.

Plant stand with lights

Campanula, you found a greenhouse on freecycle? How lucky! This is exactly what I'm envisioning. :)

John D, that's an interesting idea! I will definitely look into this! Lots of farms around here so I think it would be easy to find fresh manure!

Rhizo 1, do you have a photo of your aluminum panel set-up? We've got a couple of windows in the garage but very little natural light seems to get inside. I was planning on using heat mats but I'd never though of reflective panels.