Episode-799- Greenhouse Thoughts, Construction, Usage and Considerations — 37 Comments

  1. We had windows replaced in our home (manufactured home on permanent foundation) and we saved the windows that didn’t get broken. We saved them with the intention of making cold frames or a greenhouse or something. Today’s show has definitely given me some ideas. Thanks, Jack!

  2. Enjoyed today’s show very much Jack and your enthusisam and zeal are very evident. I also like the way you continually beat the drum that modern survivalism is multi-faceted and often dependant upon reserecting old skills in a modern time.
    The BBC produced a 13-part series in the late 1980’s entitled the Victorian Kitchen Garden. It is available on You Tube and wonderfully parallels Jack’s points.

  3. I swear you always are reading my mind. Thanks you answered my questions that I had on yesterdays show. My brain hurts and is going 90mph with so many ideas. I live in WA and it’s been below freezing for the last 5 days or more with freezing fog. The tomatoes and the peppers I have in the green house / hoop house are so far so good. I do cover them with just an old bed sheet at night. They are looking a tad stressed.

    Last year I put low tunnels over the tomatoes and covered that with old flannel sheets. We went down to 19F for two nights in a row (very unusual) well things froze. This year I have a pile of piggie and alpaca poo with some straw in there and that is the only thing that I have done differently. Oh yes and I have straw mulch. I hardly had to water at all this year using straw mulch. That could be another factor in why the plants are hanging on. I haven’t watered in a while like weeks.

    Herbs oregano sage chives rosemary thyme are all doing very very well. The basil not so much looks a little droopy. Lack of water cold? combo? I may try to trans plant and bring into the back porch and then into the house.

    Thanks again this was a fantastic show and perfect timing.

    PS When I used contractors plastic at the end of the season it started cracking by the next season it was dust. Had millions of tiny pieces to sweep/rake up. I still use it from time to time in a pinch. However only for limited periods as I don’t want to face that mess again.

    I have very thin wire cable with turn buckles at the end thread old bed sheets on to it (most of my sheets were open at one end those that weren’t I just made a little slit in the seam.) they are attached to the side of the greenhouse. I am adding another wire next to it like a double curtain rod and then attaching a wire at the peak of the green house. I can draw the sides shut the draw the second curtain shut and lift up the bottom and clothes pin it to the top wire.

    For my low tunnels I ripped 2×4 into 3-4 sections about 1/2 inch thick and then cut into 18″ long sections drilled a small hole in one end through the flat part. Screwed them on to the sides of my planting beds so that they will rotate upwards. If the hole is a few inches up from the bottom and you screw it onto the planter box in the correct place you can just step on that short part flipping up the long part the short part sticks into the ground now you have an instant frame to drape over your plants. Just throw over a cover of sorts (what ever is needed) and poof you are done. When the cover is no longer needed take it off the frame and just tap the frame flat to the ground. Poof its stored easy up easy down. Best of all it’s already attached and stored. I have even used them as tie up supports. Stand the sticks / levers up tie a string from end to end and instant trellis.

    • I got the idea for my tunnel supports from an old fashion wooden ruler. The kind that folds up.

    • @Roundabouts, awesome stuff thanks for your contribution to the site, just really great insights.

  4. Loved this greenhouse episode! My wife and I are still looking for a place to buy, but when we find our place, we’ve talked about setting up a greenhouse and attempting to grow vanilla orchids, coffee, and citrus…in Ohio. 99% of people think it’s absurd, but I truly think, with the right systems in place, and if we do it intelligently, we can make it work. I always thought we would need to do some alternative heating for nights (other than just storing solar energy) like chickens, compost, rocket mass heater, etc., but after listening to yesterdays podcast with Steven Harris, I almost think we could make it work with all solar! Exciting stuff! Now if we can just find that right property/piece of land!!

    • Oh when you get this going keep us posted that would be so great. Good luck property hunting

  5. Question on green onions: Would the same perennial effect be achieved by cutting the stalks off instead of ever pulling them out of the dirt to begin with?

    • @greenthumbelina, yea but I would figure you would loose a good inch to and inch and a half of that really nice white part. When you replant you really only need about a quarter inch if that off the end.

  6. Great episode Jack, really like the subject matter. Lots of good ideas on heating and saving heat. One of the best ways of saving heat that I have heard from a couple of customers is that they have installed bubble wrap overhead in their greenhouse. If you run a piece of wire across your greenhouse from the purlin on one side to the purlin on the other side starting at the front and adding a wire every 3 feet or so until you get to the back. That wire would be about 7′ off the ground in your house. Then you get some wide bubble wrap and lay it on top of the wire, you can actually feel the difference on your head when standing under the wrap. You can move it over to one side during the day but even if you don’t the light and heat will get through. You can also use those wires for trellising in the summer. Great idea about the under floor heat circuit too. Happy planting

  7. Broccoli will take a hard frost and sub-freezing temperatures.

    A lot of lettuce will take frost, too. The trick is to let it thaw before picking to avoid wilting.

  8. Hi jack Nice episode been thinking to do a mini wood frame plastic sheet greenhouse for a while now but just havn’t got in to gear to do it yet but nice to hear that it works well, might give it a go now.

    by the way you where almost describing an earthship ( with the south facing green house and you also mentioned the mini greenhouse that you digg down in the earth to get the thermal mass , you should check them out if you not herd of them before that is 😀 or maybe even do a episode about them ?

    love the show!!! 😀 cheers olof

  9. I built a couple tunnels over our 3 x 12 raised beds. One has 3/4″ polypipe hoops on 2 foot centers and the other uses 3/4″ emt conduit , bent into 3 1/2′ high x 3′ wide square hoops on 3 foot centers. It has a 2×4 fastened down the center with pipe clamps and is covered with 6mil poly with the long edges stapled to a 2×2 so it is simple to roll up one or both sides as needed. If you have a conduit bender, this method is easier and less bulky then a wood frame. We also have a 12x 24 hoophouse made with 1″ PVC conduit on 2 foot centers .Amazingly, it has withstood 18″ of snow on a couple occasions. Also , one issue we had with coldframes was leaving them closed because we expected a cold overcast day only to have the sun come out while we were away and returning home to find steamed veggies in our frames. Coldframes make great solar ovens if you don’t vent them ! We fixed this by installing automatic greenhouse vent openers. They use a wax filled cylinder that expands as it is exposed to heat so uses no electricity . We use a light weight version that will lift a 35 lb. lid. No problem with our polycarbonate lids.

  10. I’m drinking atm. I didnt listen to this podcast but I just listened to your podcast with Paul Wheaton. …

    I’m Ukrainian to Jack. it’s not The Ukraine. I know you are Americanized but it’s not The Ukraine. It’s Ukraine, but yeah. kinda annoyed me. . whatever I love you Jack ahahah drunk talk

  11. wait a sec I did listen to this podcast I loved it, Cause I’m up in Canada where is cold like a Id swear here …

    this podcast interested me. really needed to listen to it. thank you!

    i thought this was the steven harris podcast link. sorry

  12. Jack,

    Once again you have a show that is eerily timed just as I’m getting ready to construct a 15×15 greenhouse in my backyard.

    You gave me a great idea to finance this venture. I’ll go to the farmers market this year and pawn off several heirloom tomato plants that I’ll be able to start early.

    Thanks again.

  13. Great show Jack! It’s been too long since your last
    Gardening show. I have to agree that it is an
    Essential subject for our community. Thanks again.

  14. As you mentioned in your opener. You have to eat everyday. I think you could podcast one day a week on gardening. And given the seasons, keep it fresh and topical. So +1 for continued gardening episodes.

  15. Ive been doing a lot of reading and research for building an earthen hobbit house and we’ve been talkin about adding a greenhouse. Our concern was summer heat….well we figured puting unobtrusive doors but this episode gave me a bunch of new ideas to implement. Screens and windows that open add a whole new element. Thanks.

  16. I have been learning how to use a green house seriously for the last 18 months in this travel I have a few things to add to jacks Ideas. On a small poly green house with a non green house film thorw it away after the season it doesn’t last long with out the uv stableizers and the last thing you want is to have it fail mid season after you put all the hard work and time into your plants. use the frame that is left to hold chicken wire. This will help keep out squirels and cats and other unwanted critters.
    Everyone says to buy the widest green house you can afford. you have more area in the middle that is not as cold as the edges and you can always add to the length as your budget allows. I had listened to the family garden doctor talk to the guy from he had talked about useing poly barrels painted black and filled with soil as his solar battery. then grew warm season crops in them that like warm roots like tomatoes.
    venting is so important even in the cold of winter it can get hot during the day so plan to add a fan or have ridge venting.
    My green house ( zone 5 ) is a 12 by 24 poly tunnel with 4, 275 gallon ibc totes on the north side painted black filled with water, one is a aquaponic system. the main bed is 3 foot by 20 square foot garden style. I grow vertaily on the north side of the bed I have grown more in this area than my outside garden. runner beans don’t pollenate well till you get bees into the green house so use other types of beans to get better results. In November I added a propane live stock heater in a 2 by 4 horse tank to add extra heat battery. Late November I added a low tunnel over my bed inside the green house then I added two lights total 100 watts thermostaty controled to come on at 40. The lights uselly come on at dark after I losse my solar heat. I have cellery,radish , cabbage, swiss chard, rosemary, carrots, leeks, brocilli, dill, and a few other plants growing in there after we had several night in the -6 range and single digits for about 12 nights I had peppers on the vines till the really cold weather hit. It got down to 23 under the low tunnel during the coldest nights. My main goal was just to extend my season and I think I will be able to winter over some of my vegs. what ever survies will be used for seed next year.
    Good luck and try new things:)

  17. Interesting show .. What about a greenhouse, mini house etc for a BOL that you don’t live at ? I guess that may be less useful, although it seems like these things are portable so if you are there for some extended stay you could do it I guess.

    If it’s unattended for too long, would it tend to get buried in the snow ? Otherwise, could you grow some stuff in a small greenhouse when the temps get down to 20 degrees at night or sometimes a little colder and it is a free standing greenhouse not attached to a house with no other heat source ? The compost for heat did sound interesting however ..

    I didn’t quite understand the dynamics of how a greenhouse can cool an adjacent structure in the summer time ?

  18. Jack,

    Great show. (Ironically I listened to it as I was setting up 55gallon barrels as heat sinks in this year’s greenhouse experiment, and you we spot on.)
    Last year I did low tunnels with pvc and contractors plastic over cool weather greens. It worked well from a protection/incubation standpoint, but by the end of the season I had tired of the constant covering/uncovering/venting/sealing necessary to maintain the right band of temperatures.
    I found the sealed low tunnels to be volatile to temperature swings; left sealed on a sunny but cool day and the inside temperatures were tropical. (Note: I have seen self veting low tunnel plastic @ commercial grower supply houses, but I haven’t tried it due to relative cost).
    This wouldn’t be bad if I was trying to keep peppers or tomatoes or non-hardy herbs going, but I was growing lettuce, spinach, chard and similar. Also, the condensation inside the tarp attracted a lot of dirt as the tarps were rolled on and off dozen of times; I always had mud on my hands to some degree after messing with them. Because of the relative opacity of the 6mil whitish plastic I tried to remove it when I had any string of “favorable temperature” days and nights. The food was fantastic and I was sold on the idea, but by March I was planning on better solution for this winter.

    This year I decided to pursue a high pvc tunnel over 3 long beds in the back of my garden. (Details are here:
    A higher roof and larger volume is an advantage in managing temperature swing vs the low tunnels. Your extra volume from the raised foundation will be a +.
    I highly recommend using greenhouse poly vs contactors plastic. It is thinner, more flexible and has higher light transmission properties. Additionally, it looks better from both the inside and outside. I purchased the 1 year poly from greenhousemegastore in the 24’ width and will have 3 or 4 years worth of covering for about $100. I didn’t opt for the multi year covering since this is all still in the experimental stage and I will undoubtedly reconfigure to some degree after this season’s lessons are learned.
    1” PVC cross braced is very sturdy once the poly is stretched over it. Amazingly so.
    Self venting is mandatory, at least a partial self venting solution. I have one high window operated by an auto opening cylinder; it mediates the temps on sunny days but…. (see next point)
    Cross ventilation of some sort is needed for sunny milder days. A sunny day in the 60s here pushed the temperatures into the low 90s inside the tunnel, even with the vented window. This is good, right? Not necessarily….. (see next point)
    Brassicias and lettuce will bolt quickly if the nights are near freezing and the temperatures in the greenhouse hit the 80s/90s for more than a few days. This was a surprise I missed this year- the damn thing worked TOO well and my beautiful broccoli bolted to flowers rapidly- much faster than spring planted broccoli had (this shouldn’t be an issue in the fall by I created to perfect conditions for it. Lettuce acts the same way- it turns stalky relatively quickly and bolts. This is the bad news- the good news you can have two cycles of brassicias in the fall winter- one normal fall planting uncovered and a later winter planting covered.
    Humidity: more humid air is a good thing in general and watering is minimal. Unfortunately, this warmer humid environment is nirvana for some of the pests that managed to fund their way in. Cabbage worms went from 0 to 1000 it seems overnight (BT took care of them quickly). Slugs have rediscovered my chard and bok choi and will have to be dealt with.
    Winter seeds: I put a flat of lettuce seeds out a few days ago to replace the bolting patch and germination has been very fast and consistent, better than anything I have tried in the past.
    Soil temp and plant growth: The garlic, spinach and chard inside the tunnel is all much larger than the same outside- planted at the same time. The warmer soil is the key I believe.
    Double coverage: For my low tunnels, I pulled a tarp over the double layer on the colder nights. It made a significant difference on the inside temps and the condensation didn’t freeze @ temps of 16 with a single halogen shop light underneath. I can’t do that with this setup, but I can get double coverage on the beds by using row covers over the individual beds. I picked this and much more up from a homesteader/blogger in Michigan who has had success with poly-covered greenhouses that have no special sources of heat. ( ) I haven‘t needed it in N GA yet, but my tender lettuce seedling with likely go in the ground in early January and will be @ risk for cold damage if I don’t. (Check out her outdoor masonry oven posts too- excellent).

    I could ramble on. It I a whole new ballgame and like my previous expansions, I am having to learn the tricks as I go. Bottom line I highly recommend it.

    Thanks for what you do, I hope these snippets help.

  19. For those looking at water for thermal mass.
    I’ve been trying to design a completely passive solar greenhouse for my specific Lat. Long. that would support growing year round, with no energy inputs aside from passive solar. Accounting for the thermal losses of the structure, glazing, and ground losses and subtracting them from my estimated solar gains I’ve found that it takes about 2 pounds of water per cubic foot of airspace inside the structure to make it feasible for my specific location.

    This took quite a bit of information that is site specific. Including average temps throughout the year, Sun angles and sunlight duration throughout the year (Univ. of Oregon has a sun chart program on their site) and it also took me three days to come up with a formula to find roughly how many btu/hr per square foot the sun will put down depending on it’s angle in the sky. Then throwing it all together and mashing numbers until I was braindead, I found what I feel is 99% perfect for me.

    Long story short, no matter how bad it sounds, and how many people tell you “It won’t work” never give up and just go with the crowd.

    I hope to break ground on my greenhouse this year, if I can locate a few more components for cheaply as possible (free I hope) it’ll happen.

  20. Carpus,
    Combining the heat sink thermal mass with a cold sink might enhance your plan. A cold sink being a trench or trenches 3 ft lower than your beds for colder air to settle into. mother Earth news had a basic design illustrating this concept.

    • I have gone back and forth on a cold sink, I think I may start without one and add it later if I find it necessary. I could also use some pipe to make the cold sink a fresh air inlet during the warmer parts of the year, also use it as a pseudo root cellar in the colder times.

      Thank you for your thoughts on this.

  21. I’ve just started listening so please forgive if I repeat what you’ve already addressed.
    I so enjoyed this about greenhouses. As a girl we would just cut the green onions off at ground level and they would grow back year after year in bunches. I try to grow some tomatoes, peppers, parsley, basil, etc. in pots so that I can bring them in when it gets cold here in Spokane, WA. Yesterday, December 11, I picked a tomato, a pepper and basil.
    I have one of those closet sized greenhouses on my deck. When it gets below 25 I put a heating pad in the deck below the shelves. My 2 stevia plants are still alive as well as the lettuce, spinach, kale etc. By the way, you can eat the tips of green pea vines for salad greens and stir fry the rest of the vines. I start my baby plants early on the hot water heater in my laundry room and close to my sink. I put the tray into a plastic bag until they sprout.
    If you haven’t read Eliot Coleman’s book The Winter Harvest Handbook you are missing a treat.
    If your greenhouse is somewhat permanent, you could build a trombe wall for heat retention.
    Thanks for the reminder about soil cubes. I need to try that. I bet my worm castings, (I have three bins of red worms) would make great cubes.
    I would love to hear T.C. Sherry (of Deep Winter) as a guest.

  22. Looking forward to sharing what I have done with some small greenhouses made from recycled materials. Thanks Jack for all that you do. Love your casts!

  23. As I was saying . I would have put the door in the back of Jack’s green house and allowed for more glazing up front. It is still not too late for Jack to dig a deep pit where he will be walking and put a cat walk there to allow the cold air to sink down and push up warmer air. You could use old wooden skids for that. Maybe wooden chips a few feet deep around the house would keep the ground temp a little warmer too as it they break down.

    • @Joseph DuPont, I know you mean well dude but

      1. I have zero need for a door on the back side, there is nothing back there but think brush. If anything the wall will become a vent for the exhaust of a rocket mass heater. Insulation there will do nothing, the heat loss to the roof is so much more than the North wall that it doesn’t relaly matter.

      2. Digging a “deep” pit isn’t practical there is about 18 inches maximum to go down before you hit and absolute slab of white quartz, not rocks but a slab of bead rock.

      3. I do plan to put in vents from a cross flow of air on the back wall. This won’t require the framing of a door but will allow air pass through.

      4. Your prior comment about “clearer” glass on the front is also kind of missing the mark. Glass is glass all the glass is as clear as glass gets. I guess you mean more glass, if so there is little more to be gained.

      Keep in mind Arkansas is not PA, I don’t need as much gain as you do. It is also always easy to say what someone else should do like “dig down deep” when you don’t have any idea of the facts on the ground where they are working. Digging down deep at this location would require either the complete destruction of the track hoes hydraulics and bucket and/or explosives. BTW explosives is what it took to get my neighbors house installed, they had to literally blow out a shelf for the foundation.

  24. When setting up our greenhouse for the winter, we put down a thick layer of newspapers and paper sacks first to help with ground heat loss, covered it all with a tarp, then put our Springhouse greenhouse on top of it. We also used a 35 gallon black trash can filled with water as a heat sink. I think we probably need at least one more. The only thing I have in there right now is some pepper plants I was trying to overwinter. Your podcasts have inspired me to try other things as well, though. Thanks.

    • Well cold falls and heat rises.
      Some peopole just use 55 gallon drums and put their plants on them as a shelf. If you can have enough water to not totally freeze you will go a long way to help your plants survive the Winter.

  25. Jack,
    Thanks for a great podcast. Listened to it last week, and took it as some motivation. I have some greens planted in my 12 x 4 raised bed (also put in b/c of your show) that have been doing “okay.” I have them covered with a PVC frame and netting to keep the deer out. This weekend, I covered it all with some plastic sheeting to create a small hoop house.

    Thx for the motivation.
    – Roger

  26. I did plastic tunnels last year, and at best it held things where they were – yes, they lived, but they didn’t grow any – and I’m talking cold weather stuff like broccoli, lettuce, spinach, etc. I had resolved to say the hell with it this year – too much work for too little reward. But after listening to this episode, I ramped up one of my beds & built a new frame for it that should resist our punishing Sierra winter winds better. Thanks for the inspiration, Jack!