From my couple months experience (engineering oriented guy), I would say for green house and indoor growing, if I was limited to buying one thing and making do with scrounging up the rest, I would stock up heavily on Perlite. Bright white, it is really the most useful stuff you can find.

Uses include very necessary aeration of soil. 1/2" on top of planters or beds greatly reflects sunlight to underside of leaves, expanding what plants do with sunlight conversion. Added to compost, aerates naturally without much need for labor of turning stuff over.

I look at all of the pots and planters I bought and the structures for indoor growing I came up with (pretty successful designs I think), and there is no reason pots expense couldn't have been eliminated and beds constructed instead out of recovered free materials.

I know from previous light gardening experience, for fertilizer, if you can get any fish and maybe cut into 1/3's, bury them 1/2 or 1 foot deep and anything planted on that will grow like the dickens.

Mirrors is second item for indoor growing. So I could have done better building bed structures instead of spending a couple hundred on plastic pots. Well, I experiment and learn. Pictures coming soon. Bedroom structure 2.5 feet by 8 feet is total success, as however I did it, that growing space is always brighter than outdoors. It glows.

OK, I fooled around with indoor planted plants for 2.5 months. It took me a couple monhs to figure out what is super-ideal for plants in such a situation. I transplanted a few bean and tomato plants that were planted and grew under very bad conditions. They seem to be permanently stunted and doomed. Seeds planted a couple weeks ago are higher, even though in new growth seedling form than the ones that were screwed.

My feeling is a plant that didn't start out in the first month or two in good conditions is permantly screwed and needs to be plucked and replace with a new seedling.

Anyone have this experience?

I really want to use the sheets too – the breeze last night must have been 50mph. I need about 200 bucks worth, but the doggone shipping is at least $200 more – no local supplier that I can find.



I have a bunch of old window sash I could try for the walls but am kind of afraid of going that route since we had some tennis ball size hail a couple weeks ago - the 6mil UV poly on the roof had a few dents but was otherwise OK.

At $100 for 10x100 feet which (for me) is enough for four applications, at 4 years for each application, that $400 gets me 64 years - Heck I'll be lucky to make it to 64 myself!

I didnt get the greenhouse up last year as was planned since there were other priorities.
But after the bird turd epidemic in my winter garden and all my lettuce and spinach going to waste,I have decided that its definately going up this spring.
My original plan was to make one big greenhouse 40 or 50 meters long but I have decided to relocate the greenhouse area and make a few smaller ones with the same total sq footage.

The materials for the frame was an issue,but after much contemplation I have chosen to use thermoplastic water pipe with rebar on the inside to reinforce it and go with a hoop shape.
The frame will be held together with Ts and it will look something like this.

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Now I can also take advantage of the space between the green houses.


The size of the greenhouses according to the new plan will be 15x5m.
There will eventually be five of these,but this year I will probably put up only two,and then add on yearly.

So even though this project was put off,in the long run it seems it worked out for the best.

This indoor crap I designed and built is ONLY useful during fall-winter-spring. In summer it is useless, for my far north location, as sun is too high in the sky for this crud to work. But that should be normal outdoor growing season, or greenhouse season.

I tell you, with the perlite/peat/woodmulch/soil combo, the 2 week new seed growth exceeds the previous 2.5 month screwed plants in height, noticeably. The soil deal is the deal, along with plenty of sunlight or such like.

Looking at pH ideal and all that, per plant type. Either maximize or die off in the... bad conditions a-coming. Wished I had started a year earlier for the learning curve. Just couldn't get it going til now.

You've given me an idea. I had planned on building insulated cinderblock walls on the North and West sides, due to very intense NW winds in winter, and now I'm toying with the idea of using recycled sliding glass doors on the front, tilted in at about 25 degrees.

Now all I have to do is think about the roof; polycarbonate, or standard opaque roofing?

I like the idea of rain water catchment to a barrel set inside, as the water can also retain heat at night during the winter.

I read once about using dual-pane replacement French door glass since it is a standard size and so mass produced and about the cheapest new glass available – still too rich for me though I expect!

I’m doing a remodel similar to your ide on our old garage-cum-greenhouse. Replace the south and some of the east wall with poly, replace the south-facing slope of the gable roof with poly, fur out and insulate the north slope of the roof as well as the north and west wall with 10” (R-22?) insulation, line the north wall with 55 gal drums of water.

Of course, as in all of me projects, I’m only a quarter of the way there. But I have maybe 4 dzn 6-packs a-growing with the help of a heating mat so at least it is functional.

We used a non-standard size insulated glass, even though we had planned to use a standard replacement size glass for sliding patio doors (if I recall correctly they are 34 by 76 inches and 46 by 76, but I may be off). I got a non-standard size because I got a pallet of it at an auction for much less than I had planned to pay, and have enough left to redo the entire structure.

I think that insulated (patio door) glass is worth using, inspite of the cost, because of the potential long life. Maybe hundreds of years? if not physically broken.

I would use vertical glass in the south wall with NO tilt unless you want peak heat in the green house in late spring or summer instead of winter. Almost anywhere in temperate climates (probably anyplace you would want a greenhouse), vertical glass admits the most solar energy in mid winter, as it is closer to perpendicular to the the sun's rays, and reflects less of the light. As the sun rises in the sky, more light is reflected from the glass as the angle of the sun's rays increases. With a modest roof overhang, it is possible to almost completely shade the south facing glass in mid summer, reducing the heating effect in the greenhouse, making it a more usable space in the summer. Ours is probably hottest now (late March through April), and then as the sun is higher in the sky, there is some shading of the glass and the greenhouse cools down as there is little direct sun shining in it. Hope that makes sense.

For an economical dual wall solution one can use double nylon.A lot of the commercial greenhouses are set up that way here.
Also in a sunny winter climate area,a solar air heater or two will do a lot.

Especially if it can be picked up from a contractor who replaces older sliding glass doors and wants an easy disposal of them.



Yes, that makes sense, though it depends on whether or not one chooses to make their roof opaque or transparent. If transparent/translucent, then the same disscussion arises. Most commercial greenhouse operators use automatic vents to lower heat generated from summer solar gain. Shade cloth in varying degrees of opacity is inexpensive as well. If people have opaque roofs, then can they grow much inside besides shade plants in the summer? Alot of it depends on the North-South width of the greenhouse.

I'm in Northern Virginia, so I'm in Zone 6, about as middling temperate as they come.

The question of roofs and even overhangs depends on whether the room is used for anything other than a greenhouse I guess.

In my case I’m most concerned about keeping the temps above freezing with as little additional heat as possible in late winter/early spring. So we need to get as much light as we can to the north wall to heat those drums. As was said shade cloth could be used in summer.

Our greenhouse/sunroom is 14 feet deep (wide?)--anyway, it extends about 14 feet out from the south side of our house, and is 25 feet long, the length of the house (its an old square farmhouse). It has a low pitch sloping shingle roof with 2 skylights that can be opened. We put in the skylights for possible ventilation, and if I were to do it again I would not do the skylights. The floor is ceramic tile, a close out pattern, on a cement slab that has tubing for future radiant heat in the slab, and insulation under the slab. Ceiling has 10 inches of fiberglass batt insulation in 2 by 12 rafters. South wall is glass and some 4x4 posts between the glass, supporting the roof, end walls (east and west walls have some glass plus an operating tall casement window, and a door in the east end. Ceiling on the low side is about 8 feet, and about 14 feet on the high side. We sometimes get a bit of frost if it is cold and cloudy--and by cold I mean minus 40--for a couple of days, and then we might get down to freezing in a few spots in the room during the night. If the door to the house is left open, there is no chance of frost. It is a usable space for starting plants for the garden, overwintering some tomatoes and peppers and lettuce, etc., plus small citrus trees, and a nice place to sit on a sunny winter day.

Did you build that yourself? Why not skylights? Think they lose to much heat at night vs the gain?

We have a perfect setup to construct something like that. Sliding glass doors go out onto the deck on the south side of our house. There are some big trees about 25 feet out, but the sun still comes through very nicely.

We have a roof that overhangs the house by a good 18 inches or maybe more. I wonder if its just to keep the rain away from the foundation or does it serve some higher purpose?

While primarily for inhabited building design, a program called Solar 2 can depict the sunlight reaching into a building throughout the year, and give BTU estimates for each hour of the day.
Solar 2

Cool program! Lots of other nice time wasting toys there too, thanks. Although I couldn’t talk it into modeling my transparent roof, I can get an idea of whether to make the entire south slope open or not by viewing the wireframe – with a little more playing of course!

BTW I shortened your link


Your greenhouse sounds great Jim, I’d love to have that setup, and our location would be perfect too.

Frank not only does the overhang protect the siding somewhat, in the summer it shades the wall and especially the windows but most importantly; gives you somewhere to hang your Christmas lights!