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RE: ever get nailed by a power outage? (Follow-Up #2)

posted by: curlygirl on 06.20.2012 at 02:35 pm in Greenhouses & Garden Structures Forum

Great question! That is something that really concerns me. I want a greenhouse that is resilient to many challenges and so we are building strategies into the design. Among the many years I have been researching this, here are many of the following design strategies I have come across and am seriously considering:

Passive Solar Design
Orient the greenhouse so that most of the glazing faces south and is angled to best take advantage of the sun. In the winter, the sun's lower position means its rays penetrate more deeply into the greenhouse, warming all the surfaces. The design takes advantage of this by having many heat sinks (aka "high thermal mass" or "thermal stores") which soaks up the heat, holds it and then releases it when the sun goes down, extending the heating time frame. The northern wall is heavily insulated to reduce heat loss. Starting a design with Passive Solar principles in mind is a strong first step in making your greenhouse more resilient because it is not dependent on fossil fuels for it to work. However, it has its limitations. It is great for season extension and when combined with other strategies can be used for four season growing. It all depends on where you live, your property's attributes and what you are planning on growing.

Pit Greenhouses
This design uses the earth's stable temperature (roughly 55 degrees year round under the frost line) to maintain temperature. Just as the name implies, the greenhouse is largely underground, often with just a glass roof. By limiting the glass, you are limiting all the ways that warm air can escape and cold air can get in during the winter. The beds are all raised and the pathways are sunken which keeps the plants safely above the coldest air. The cold air sinks and then gets warmed by the earth, rises and the cycle continues. When the sun is out, it warms the thermal mass of the earth which also stores heat for the night time. Innovations, Inc. Unveils Pit Greenhouses.pdf

Attached Greenhouses
There are many benefits to having your greenhouse attached. The convenience of simply walking from one part of your house and into the greenhouse is huge -especially in the winter with high snow- but you also have the advantage of sharing heat. When the sun is out in the winter, you can open the connecting door and let in the extra heat into your house. At night you can let your house's heat into the greenhouse. However, it is not as simple as it sounds. It is best to design a system from the outset that circulates the heat naturally -often just opening a door does not create a significant enough draft to really circulate the air. And, to really generate heat for your house, you would need it to get to temperatures too hot for the plants. So, this is not something you should count on. Also, in the winter, greenhouses generate a lot of humidity which could create problems for your house.

Subterranean Heating and Cooling System (aka "Climate Battery or "Seasonal Store")
This innovative heating system captures the hot air of the greenhouse in the summer and stores it underground; and cooler, dryer air comes up to replace it. Over the course of the summer, the earth below the greenhouse has so many BTUs stored that you can actually heat your greenhouse in the winter with summer heat. To heat a 1200 square foot space, it requires a slow moving fan that uses the equivalent amount of electricity it takes to power a large refrigerator. The fact that SHCS takes the hot humid air, puts in underground and cooler, dryer air replaces it, means that you are controlling the excess humidity -a really handy feature- and you are both cooling and heating the space with the same system. It is simply taking heat from one area, storing it, and then moving it again when needed. This is a form of Geothermal Heating only it is cheaper and it also has the dehumidifying feature so needed in a greenhouse (and the humid air of the greenhouse makes for a super efficient system because of the phase change that occurs). In terms of a power outage, I would feel comforted that my plants and trees would be sitting on top of my heat storage even if the fan that circulates the air could not operate. It would be unlikely the greenhouse would outright freeze.

Geothermal is very similar to SHCS -rather than burning energy to produce heat, it is simply moving heat from one place to the other which is far more efficient. The upfront costs are very expensive but over the lifespan of the system it is the cheapest way of heating and has far less maintenance. For houses, the payback period is between 5 to 7 years (with government tax incentives). Unlike SHCS, Geothermal can be used to both heat the greenhouse and the house. It also has a lot of health benefits because the burning of natural gas and other sources of heat has health consequences.

Phase Change Materials
There a number of materials that can store heat at one temperature and release it at another. Water is one of them. Often in a Passive Solar Greenhouse, there a large amount of water barrels used to absorb heat when the sun is out and then release it when the sun goes down. Many have reported great results from doing this, others not so much. The main limitation is that water takes up so much space that could be otherwise used for plants. There are other phase change materials that can store a lot more heat for a fraction of the space. And SHCS is a phase change. The hot humid air is pushed underground where is the cooler temperature forces a due point. The water vapor is release, carrying with it the heat. Sunny John (who promotes SHCS) estimates that five times the amount of heat is stored because of the phase change.

Thermal Solar in Radiant Heated Beds
Using thermal solar panels, you can heat water or some other liquid, and run that through a radiant heat system that heats the soil of your beds instead of the air which is much more efficient and less heat is lost through the glazing. Plants and trees need their roots to be warm more than the air around them. If their roots are toasty than they can take a fair amount of cold air from time to time. However, some plants may get out of whack because they do need a certain amount of heat in proportion to the light they receive. How you run the pipes through your soil is a bit of a design challenge. You probably don't want them directly in the soil because you can inadvertently burst a pipe when working with tools. You may be able to design it into the walls of the beds.

What I plan to do . . .

I am concerned about Peak Oil (and Peak Everything!), Climate Change and economic uncertainty and it may seem that building a greenhouse might be extravagant with such concerns but I think greenhouses will become a handy feature of a house in the future. The key is to design one that is not a resource hog!

For awhile, I had concluded a passive solar attached pit greenhouse (with the glazing tall enough to grow fruit trees) would be the ideal design. Then I learned about SHCS and thought that I could integrate that into the design as well. However, when we finally found a property that had enough southern exposure, we find now that the high water table is probably too high and may interfere with the SHCS tubing. So, we probably won't do the pit design and I am hoping that the heat storage below will provide the freeze protection that a pit design would give us in a power outage. I am also concerned that being in Massachusetts I might not get enough solar exposure to heat the greenhouse year round. We are looking into another heat source -any suggestions?

So now we are considering geothermal. We have natural gas for our house and I am concerned that although the price of natural gas is not so bad now that in the future it will be. I also rather not use a fuel that is sometimes retrieved by fracking. Geothermal is so expensive in upfront costs that we may not be able to afford it, however, our state does offer some loans and there are federal tax incentives. Geothermal would allow us to both heat our house and greenhouse, however, we would not get the benefit of the dehumidifying that the SHCS would provide us. I'd like to do a hybrid system but we are not sure if we can afford both.

In addition, we are designing a rain catchment system with an underground cistern and a root cellar. With the typical rainfall we get in New England, we could provide all the water we need for our greenhouse, household and gardens if we have a cistern big enough to store the water during rainy periods.

As for what to do when we go away. We have a number of neighbors who are just wonderful! This spring we created a garden on our property for three households to use. We built it all together and when one of us goes away, we have each other to look after the garden plots. -I used to have to hire someone to water my garden! We plan on doing something like that for our greenhouse where we invite friends and neighbors to enjoy it on some level whether is by sharing the harvest or spending time in it on a cold wintery day to lift their spirits. Little by little, we will show them how it works so that when we go away, we'll have knowledgeable people we can count on.


clipped on: 05.06.2014 at 11:54 pm    last updated on: 05.06.2014 at 11:54 pm

RE: Row Cover Gardening (Follow-Up #33)

posted by: Hudson...WY on 09.28.2012 at 09:09 am in Greenhouses & Garden Structures Forum

The mesh is 47" 12 1/2 gauge Field Fence available at most farm supply stores - a full roll is 330' but most stores have smaller rolls as well. I cut the fence in 6' lengths with small bolt cutter or wire cutter and cut the vertical wire such that there is 6" of wire on both sides of the hopes to push into the ground to anchor the fence. The center height is approx. 24". I plant in wide rows of 30". The mesh size is 6" squares (for easy reach-in, weeding etc.) although the bottom couple of rows are a bit smaller. I gap the fence in the rows approx. 18" to reduce the cost and because the row cover does not sag with the gap. I like the fence because it will last many years and I live in a climate where we have had snow every month of the year and periods of hail or strong wind. The fence does an excellent job holding up the weight of the snow and withstanding the wind/hail etc. It pulls out easy at season end and stores by stacking one inside the other. I have never tried PVC pipe so I am not in a position to compare. I am sure this fence method is more expensive but I like the way it performs.


clipped on: 05.04.2014 at 06:15 am    last updated on: 05.04.2014 at 06:16 am

RE: Row Cover Gardening (Follow-Up #17)

posted by: karin_mt on 12.27.2010 at 12:47 am in Greenhouses & Garden Structures Forum

OK, here are some photos:

Overview - basically it's a simple perimeter fence. Instead of making a T like Dan's. we just put in vertical posts at each corner and then every 8' along the row. Next year we'll add a lower strand of wire to catch the shorter canes.

Close-up of the wire tensioning device - a threaded hook with a nut on the end. Spinning the nut adjusts the tension. The wire is basic fencing wire.

Summertime view. A William Baffin climbing rose sits at the midpoint in the rows and there is a gap in the raspberry fence here so you can get in between the rows here. This is best done while wearing long sleeves because the rose is even thornier than the raspberries, so it's a bit tricky to negotiate. That said, I wouldn't trade this magnificent rose for anything!

Time to make jam! This is from the year before last, early August. Yum.

Thanks for the info from the extension Dan. I can only hope that my crop keeps going for awhile longer, as moving it is not a great option at this point. After all the canes died last winter, things filled in well this year with the exception of one area.

I have lost track of which varieties I have where. I planted a wide range of them: Boyne, Redwing, Latham, Heritage, Royalty. However I did not keep detailed notes about which type is where, and at this point they have all spread around. I didn't realize that Redwing and Heritage are fall-bearing - all the types produce at similar times for me. Nowadays I keep meticulous notes about everything I plant and so it bugs me that I am relatively clueless about my raspberry types.


clipped on: 05.04.2014 at 04:43 am    last updated on: 05.04.2014 at 06:12 am

RE: Best way to fasten aluminet shade cloth? (Follow-Up #14)

posted by: mudhouse on 04.13.2010 at 02:24 pm in Greenhouses & Garden Structures Forum

Thanks, I love my mosaic bench/sink area. Honestly, it's usually got so much dirt and crud on it, it never looks like those photos in my blog anymore. But, it works!

Having the thermostats in full sun will definately skew your readings, but I can't say how much. This is my first greenhouse too, but I read that it's best to locate thermostats close to the center of the greenhouse, close to (or just above) plant level, and out of direct sunlight. Because the thermostats are basically the "brains" of the greenhouse, I figured it was worth a bit of hassle to try to hang them in a good spot. Also, I tend to slop water everywhere, and knew that mine would be safest if they were hanging from the ceiling...but with your slick system, that shouldn't be a problem.

Here are a few threads/links that might give you more ideas:
Thermostat location
thermostat placement in a greenhouse
how to install a greenhouse thermostat

I spent time with your blog this morning, and it's really good (and fun to read.) I love the stone foundation, stoplight lenses, and the row of glass bottles (being a closet fan of funky folk art and bottle houses...)

I think the important thing is to have fun, and it looks to me like you're doing a great job of that. You are right that everything always costs more than we think it will, but I figure at the end of my life, I won't be saying "I wish I hadn't spent money on interesting hobbies that taught me stuff...!!"
Good for you.


clipped on: 05.01.2014 at 08:12 am    last updated on: 05.01.2014 at 08:13 am

Pics of my first lighted grow the bathtub!

posted by: squirrellypete on 11.15.2012 at 11:13 pm in Growing under Lights Forum

Well as I mentioned in another post I think I found the perfect location for a lighted grow rack, in an unused bathtub in our loft bathroom. Feel free to critique it. Just don't critique the dirty-looking floor of my bathtub....I've been tracking my muddy shoes in and out of it while I worked lol.


The bathtub perfectly accomodated 4 foot long shelves however I was limited in the width by the base of the tub which was just a little over 18" at the very bottom. So if I want to use the full height of the enclosure from floor to ceiling then 24" shelves were out of the question, at least on the bottom half. I know alot of standard flats are approximately 22" so if I get some of those they'll just overhang some on each side. However, I am currently getting free 18 plant flats from Lowes and theirs are exactly 18" long so that works out. As you can see I have room to hang at least two more tiers of lighted shelving underneath this one, but I didn't want to get carried away until I tried one and knew it would work. The flats in the pics are currently empty, just wanted to see what it would look like.


This is a VERY tiny bathroom so I decided it would actually be much easier to hang the unit rather than erect a big old free-standing shelf. You can easily add, subtract or adjust the tiers as well as the lights with chains and "S" hooks, much easier to carry in the pieces than try to bring in an entire unit or try to build it inside of the bathtub.

I wanted to use things I already had or had scavenged. I already had one of those $80 chrome 5-tier shelving units I bought from Lowes some years back to store my plastic pots outdoors, and since those are now being stored elsewhere it was just sitting empty. However it was rusted so badly that despite WD-40 and a couple of hours of effort it could not be re-configured, several sections of legs and 2 of the shelves were completely stuck. So after deciding to instead hang the shelves I cannibalized the portions I was able to get loose. I saved two of the 6 foot legs which are very rigid and sturdy, cut them to the span of the bathtub and added some 1" rubber chair bottoms to cover the ends. These chair bottoms are identical to the rubber ends on a shower curtain rod. Except for the top shelf which I added to sit across the steel cross pieces, all of the lower shelves are the 18" X 4'ones from the chrome unit. That big reflective thing in the foreground is the track for sliding shower doors which we never installed and instead went with a traditional shower curtain. It's kinda' in my way so I'm going to remove that whole track (finally). I'm also going to securely mount the power strip to the wall and tidy up the electrical cord situation so it runs tightly along the trim boards and down to the electrical outlet. I can't stand a mess of electrical cords, this was just temporary to get it up and running tonight.



I did buy a 20" X 4' long wire closet shelf from Lowes which sits on the top of those two cross pieces. I quickly zip tied it to the two rods which locks everything on that level together. There is a little room between that shelf and the wooden ceiling so I plan to use that rack as my seed germination level since they don't really need light until they germinate, at which point they'll be moved down to a lower lighted tier.

I also plan to line the bathtub on three sides, possibly the ceiling as well with mylar. I may even hang a homemade mylar curtain between the shelves and the exterior shower curtain. I don't know if all that will be necessary. Will have to see how it goes. I can also add small fans to each level if needed to help the seedlings grow sturdier and will eventually add a light timer, for now doing it manually. Right now I've got the lights on a power strip so I can just flick the switch and both come on or I can use the pull chains for individual units.


What I like about this set-up is that room stays between 70 and 80 degrees on any given day, even in the winter time. Being at the top of the house and the adjacent office containing loads of electronics, it is always warm up there so I don't think supplemental heat for germinating will be necessary. Also, I still have a regular pretty fabric shower curtain in front of everything so I can just pull the curtain closed and TA-DA! It's back to a useable bathroom for guests with no one the wiser. That bathtub has never once been used in the 10 years we've been here for anything other than storage.


Of course, even with the shower curtain closed if the fluorescents are on it's not completely disguised as a bathtub. Oh well.

I cannot wait to start some veggies and flowering plants in this puppy!

Thanks to everyone else who has posted their setups for inspiration. Danielle


clipped on: 04.29.2014 at 06:36 am    last updated on: 04.29.2014 at 06:37 am

RE: Passive solar heating (Follow-Up #9)

posted by: curlygirl on 09.04.2012 at 05:09 pm in Greenhouses & Garden Structures Forum

I just heard back some encouraging news from Rgees. They recommend my putting encapsulated PCMs within the heat sink of the SHCS -along with the soil and/or gravel. That way, I can have the dehumidifying benefits of the SHCS along with the extra heat storage of the PCMs. Please note that SHCS is a phase change system -it is just that my high water table has me pursuing this other avenue (if my heat sink was flooded, it would take away my heat and -if this happened enough times- would fill my tubing with dirt).

AZjohn -I know what you mean about SHCS! Have you been looking at Sunny John's site? He used to have great forums where people could discuss their plans and challenges. I used to read them all the time when I was renting and could only dream and research. Now that I have a house and could use the forums to ask for feedback on my particular challenges, the forums are gone! However, I have some good news. SHCS is alive and well! Check it out:

KimHat- I know you can store PCMs in other materials such as metal tubes but I am having trouble finding that information right now. I would just go on the greenhouse fashions blog and ask questions in the comments. The blogger, Nina Reinhart, works for Rgees and is interested in getting PCMs into greenhouses. I think primarily because it would help their company expand into a new market but also because PCMs are absolutely perfect for greenhouses. The large temperature swings, the limited space, the high cost of heating and cooling, etc. Anything you can do to reduce temperature swings passively is something that will pay you back every year. I say all this without knowing what they actually cost but I think if you are in the planning stages of your greenhouse then it would make sense to think about how to incorporate them into your design. You can add them later but for me, aesthetics are pretty important so I am working them into the design now.

Also, there is another PCM product made by another company called Bio-Based PCM which you can integrate nicely into your house and it actually acts as a moisture seal too:

Cole Robbie (love the name, by the way!)- where do you live? What are you growing in your greenhouse?


clipped on: 04.27.2014 at 11:04 pm    last updated on: 04.27.2014 at 11:05 pm

RE: Shade Cloth Questions (Follow-Up #5)

posted by: mudhouse on 03.13.2013 at 11:15 pm in Greenhouses & Garden Structures Forum

I've been using Aluminet in many ways on my greenhouse, coming up on six years, with no failures or problems. I hope I don't have the problems fruitnut mentioned (so far so good.) I first purchased 40% for the roof, but that was not nearly enough protection for my plants during the intense summer months. I later changed it to 60% for the roof, and used the 40% aluminet elsewhere.

It's very versatile, and easy to work with because it's so lightweight.

I made a cover for my roof, by folding over the raw edges, hand-sewing with a big needle and strong nylon thread, and adding grommets. Then I used it to make screen panels for the south wall of my greenhouse, by stretching it inside the Home Depot metal frames for making your own window screens. I've also made a simple curtain out of it (hand-whipping the edges, again) that slides on shower curtain hooks on a rod over my greenhouse doors (lets the breeze through, but keeps the sun and birds out.) I've wrapped it around a wooden frame for my greenhouse gable, and stapled it in place with a staple gun. Really easy to work with.

Rosiew, the appearance is very silvery and shiny/sparkly. It has a fairly loose weave and stretches quite a bit in one direction. It doesn't look organic at all, though, and at first I was a little disappointed with the shiny metallic look. I used to joke that it made my greenhouse look like the Starship Enterprise. The stuff works so well for me, though, I've stopped worrying about that.

If you'd like me to send a small piece in an envelope, so you can see the material for yourself, send me an email through Gardenweb. I have lots of little scraps.


clipped on: 04.22.2014 at 02:09 pm    last updated on: 04.22.2014 at 02:10 pm

RE: Foilastic glazing tape/HFGH (Follow-Up #13)

posted by: mudhouse on 03.12.2013 at 03:23 pm in Greenhouses & Garden Structures Forum

OK, I'm back. Eastpenna, ordering from Harbor Freight is sorta like herding cats through a three-ring circus. Always an adventure. ;-)

The person you spoke with was incorrect and/or confused; the clips are still available.

Here is the info you need to call back with. The clips are identical for both the 6x8 greenhouse and the 10x12 greenhouse. However, Harbor Freight uses different part and SKU numbers for each kit. I asked him to look up both for us, so I could post it all here. He said to be sure to give them the SKU number and that will avoid confusion. (Good luck with that, lol.)

For the 6x8 greenhouse:
Part number 46 panel clip
SKU number 27339, set of 72 clips, $9.99

For the 10x12 greenhouse:
Part number 53 panel clip
SKU number 29457, set of 130 clips, $15.99

Hope this helps, feel free to post back if this doesn't work. Be prepared to speak slowly and be persistent. ;-)


clipped on: 04.22.2014 at 10:24 am    last updated on: 04.22.2014 at 10:24 am

RE: South, true south, solar noon - orienting a greenhouse (Follow-Up #1)

posted by: TomSlawson on 03.13.2013 at 11:59 pm in Greenhouses & Garden Structures Forum

Play with the program in that link a little. You can change dates, drag the cursor to your house, all kinds of stuff. A very instructive view is "path + rays." After playing with it for a while, you will realize the sun is so far south in the winter that as long as you long wall is pretty much south, it is no biggie.

Here is a link that might be useful: Sun position calculator


Alos see links in post a little further down in the thread.
clipped on: 04.22.2014 at 10:18 am    last updated on: 04.22.2014 at 10:19 am

Another way to use thermal mass

posted by: steve22802 on 02.27.2013 at 09:50 am in Greenhouses & Garden Structures Forum

i just wanted to share another way to use thermal mass that I've recently found to be quite effective. My homemade greenhouse has single pane tempered glass on the roof and as you might expect it doesn't hold heat very well overnight. So instead of trying to heat the whole 12x16 foot greenhouse I made a rectangle on the ground using 5 gallon vegetable oil jugs full of water then I put my seed flats and dahlia pots inside the rectangle. At night I cover the whole thing with old blankets and deck chair cushions for insulation.

I've just been doing this for about 4 days but it seems to be working quite well. There was one night where the outdoor temperature dipped to around 20F after a sunny day. The temperature inside the greenhouse dropped to around 30F but under the blankets the temperature stayed over 50F. Two days ago was a sunny day and the water warmed up nicely. The outdoor overnight low was 27F but under the blankets it was 54F. Yesterday was rainy and overcast so I didn't uncover the pots at all. This morning the temp in the protected area was 49F after two cold nights and a full day with no solar gain at all. (The overnight low last night was only 36 so that helped slow heat loss too.) Today is forecast to be 54 and partly sunny so I have the jugs uncovered hoping for a solar recharge.

Obviously this won't work for tall plants but for getting an early start with seedlings or potted dahlias that can fit under the 14 inch height limit of the jugs it works pretty good.


I use a long 4x4 to keep the blankets from sagging onto the pots.

All bundled up for the night.

Older picture of my greenhouse


clipped on: 04.22.2014 at 10:15 am    last updated on: 04.22.2014 at 10:16 am

RE: OK - getting the greenhouse going for the season! (Follow-Up #10)

posted by: Hudson...WY on 03.11.2013 at 08:15 pm in Greenhouses & Garden Structures Forum

OK - The photos on this post motivated me to do some planting! I am jealous of Those of you that live in warmer climates (but not enough to want to move) - so I will just have to improvise - with 2+' of snow on the ground and freezing temps in an unheated GH. I have no idea if this will be successful but We are going to give it a go! The GH temp this morning was 32 degrees. The tomatoes survived the night and I will set the timer to give them as much darkness as I can but keeping them warm as OS temps dictate. As we move towards spring - I should be able to give them more darkness. If anyone as tried this method please give us some advice! The GH is going for the season. Oh, by the way - I still have back up starts in case this idea fails...... We had ripe tomatoes the middle of June in 2012. We are one month earlier planting tomatoes in our GH this year. If this idea works - we may have ripe tomatoes by the end of May??

This post was edited by Hudson...WY on Mon, Mar 11, 13 at 20:39


clipped on: 04.22.2014 at 06:46 am    last updated on: 04.22.2014 at 06:46 am

RE: OK - getting the greenhouse going for the season! (Follow-Up #2)

posted by: billala on 03.10.2013 at 04:11 pm in Greenhouses & Garden Structures Forum

Having grown up in my Dad's commercial greenhouses in Indiana, I tend to take a utilitarian approach to greenhousing, i.e. far more attention to usefulness than beauty. The following photos definitely show this.

Down here, we're in the middle of the winter growing/harvesting season. In this climate, we harvest baby lettuce and swiss chard all winter in a squirrel/jay-proof "screenhouse". We have to grow 4-5 crops of lettuce for a continuous supply, but just one swiss chard crop supplies us all winter. Most winters we have to cram the lettuce into the greenhouse a time or two for a day or two at a time, when the nighttime temp falls below 26̊F. It never got that cold this past winter, so the lettuce stayed in the screenhouse continuously.

Lettuce nearing end of harvesting (2d crop of season):

Romaine and Green Lollo 2d crop:

Cherokee Red 2d crop:

Next Lettuce Crop (3d of the season):

Romaine in 3d crop:

Red Lollo and Cherokee in 3d crop:

Bright Lights chard:

Fordhook Giant chard:

The spring tomato and herb seedlings are well along. The herbs can stay outside, but the tomatoes must go in containers which are moved into the screenhouse when the lettuce is finished, and as the tomatoes begin to mature, again to combat the squirrels and jays. If successful, the tomatoes will be ready for harvesting in May through June.

Tomato, basil. parsley and sage seedlings:

Tomato volunteer "rescued" in October:

Three of the four tomatoes on the volunteer after five months:

Overwintered herbs:

Overwintered Meyer Lemon:


clipped on: 04.22.2014 at 06:44 am    last updated on: 04.22.2014 at 06:45 am

RE: ventilation fan (Follow-Up #1)

posted by: cuestaroble on 04.07.2013 at 09:19 pm in Greenhouses & Garden Structures Forum

The recommended air exchange rate is one volume per minute. Therefore, you need 3800 cfm fans, without any additional passive ventilation. For only passive ventilation, the roof vents should be 20% of the floor area, and the bottom side vents should be 10% of the floor area.


clipped on: 04.21.2014 at 10:55 pm    last updated on: 04.21.2014 at 10:55 pm

RE: Carbon footprints and environmental responsibility (Follow-Up #39)

posted by: sdrawkcab on 08.18.2008 at 10:28 am in Greenhouses & Garden Structures Forum

"There are times and crops that outpace conventional agriculture. Certainly, we may be able to equal the output with a much smarter approach than to blanket spray everything all the time. I am not saying you are wrong, just not completely correct."

Can you provide some examples of crops that can be grown organically and produce higher (or even comperable) yeilds than plants grown with chemicals such as fertalizers and pesticides?

When you say "Blanket spraying everything all the time" I'm not sure what you mean? In real life, farmers don't spray unnessicary chemicals 'just because'. Think about it from the farmers point of view- they have to buy the chemicals, and pay for the labor and equipment to apply those chemicals. Why would they incur all this expense that can not be passed along to the consumer to treat pest or disease problems they are not experiencing? Remember, produce is a comodity; if my tomatoes cost me 65 cents a pound becasue I have so much tied up in all the chemicals I sprayed them with and the farmer down the road is selling his tomatoes for 42 cents a pound because he didn't spray as much, buyers will be purchasing his tomatoes and not mine.

I've done a lot of work with hydroponics in college and in my free time. Aquaponics uses the same basic methods ony with fish providing the bulk of the nutrients for plant growth. Any form of "ponics" can be successful in a lab setting where all variables are monitored and controlled but it will be a while before the deserts of north Africa can be converted to fertile aquaponic farms.

If you are interested in this type of culture, i've attached a few pictures of some of my hydroponic systems:








clipped on: 04.17.2014 at 10:03 pm    last updated on: 04.17.2014 at 10:04 pm

RE: GH Benches (Follow-Up #6)

posted by: qrper on 03.04.2013 at 07:45 pm in Greenhouses & Garden Structures Forum

another photo,


clipped on: 04.16.2014 at 11:28 pm    last updated on: 04.16.2014 at 11:28 pm

RE: GH Closed for the Year (Follow-Up #4)

posted by: Hudson...WY on 11.08.2013 at 10:22 pm in Greenhouses & Garden Structures Forum

Hi Danielle - haha - yes, hauling 16' panels can be challenging ! I don't suppose they can deliver them for you or maybe borrow a neighbor's trailer? I know it can be a hassle. Bolt cutters work well to cut the panels and once they are installed - they will last as long as your GH so you only have to do this once!

Here is a photo of what I think you are after. Please let me know if they don't show what you are looking for. I wired the panels to the galvanized pipe that hangs from the GH rafters with stout chain. I spaced the cattle panels about 16" from the GH roof panels to allow plenty of room for the tomato plants to grow in-between. Good luck with your setup - it has worked well for us !

 photo image_zps03f4eb6c.jpg


Great idea!
clipped on: 04.14.2014 at 09:04 pm    last updated on: 04.14.2014 at 09:04 pm

RE: Solar Greenhouse Heat Sink (Follow-Up #12)

posted by: hex2006 on 01.05.2010 at 10:29 am in Greenhouses & Garden Structures Forum

we`ve been down to -8C this winter so not as cold as some places. The driving force is the sun so air tempering is probably a better term than "heating", it tends to conjure up images of propane heaters and the like :)
Air is drawn down the center of the plenum where it meets a cone deflector which directs it into the 15 lower tubes.
The air travels through the lower tubes and back towards the plenum.
The recirculation feature is located at the point they reach the plenum and the air is either drawn back into the intake or directed to the outlets which are the holes at the top.
The heat collection (and cooling)process is driven by a 700cfm 10" duct fan, variable speed controller and a differential thermostat. I sized the fan to provide upto 45 complete airchanges per hour for experimenting but 10-20 would be quite reasonable. The greenhouse is 9.5ft high with a volume of about 900cubic feet.
These were the results of some tests i did using different fan speeds,the soilmass temperature was 13CF (55.4F)at 3.5ft deep.
200cfm intake temp: 28C (82.4F) Outlet temp: 13C (55.4F)
400cfm intake temp: 30C (86F) Outlet temp: 15C (59F)
677cfm intake temp: 30C (86F) Outlet temp: 17C (62.6F)


clipped on: 03.18.2014 at 04:33 am    last updated on: 03.18.2014 at 04:33 am

RE: Is anyone using a shcs in a cold climate? (Follow-Up #10)

posted by: hex2006 on 12.02.2010 at 02:01 pm in Greenhouses & Garden Structures Forum

Night time lows of 10F (-12C) with greenhouse soil temps reasonably steady at 50F (10C). My 150sqft greenhouse is very small compared to most that have a shcs installed.
The shcs consists of 180ft of 80mm perforated tube arranged in a 2 layer radial loop pattern (a giant 15 armed octopus buried in the greenhouse floor). The lowest tubes are 4ft deep with a central plenum driven by a 700cfm 10" duct fan.

Six hours of sun per day would be nice but its not very likely with only 6 hours of daylight available :)


clipped on: 03.18.2014 at 04:10 am    last updated on: 03.18.2014 at 04:27 am

RE: North Side cinderblock wall: Heat sink or insulation? (Follow-Up #4)

posted by: hex2006 on 10.09.2009 at 12:21 pm in Greenhouses & Garden Structures Forum

Install the insulation vertically on the outside of the wall and extend it below ground a few feet.
If thats not possible you can install the sheets horizontally instead with a slight slope away from the greenhouse (google for "wing insulation" for more info). Use extruded (xps) polystyrene / blueboard as its the only thing that doesn`t soak up water and become useless after a few weeks.


clipped on: 03.18.2014 at 04:21 am    last updated on: 03.18.2014 at 04:22 am

emt trellis elbows -- pvc

posted by: luke3026 on 04.03.2010 at 12:41 pm in Square Foot Gardening Forum

Last year, I followed Mel's instructions of making trellises out of 1/2" EMT conduit placed over rebar hammered into the ground. But the elbows he recommends (metals ones with screws) are about $5/ea around here -- would have cost me $40 in elbows for my setup. At Lowes I found some 1/2" PVC elbows, threaded on both ends. I hammered these onto the trellises and they seemed to hold pretty well, and at $0.50/ea. I really liked the price. Well, after one season they are still holding up well. A couple popped off when moving them for storage, but I was able to pound them back on. So it seems as though they'd last at least a couple years, and are cheap to replace. Just a suggestion for the budget-conscious SFG'ers out there.

Here is a link that might be useful: Garden blog


clipped on: 02.21.2014 at 09:38 am    last updated on: 02.21.2014 at 09:38 am

Improving your 6x8 HFGH

posted by: dewey1945 on 01.25.2013 at 11:22 am in Greenhouses & Garden Structures Forum

HF greenhouse owners cite four major shortcomings for the 6x8 unit. Premature panel failure (poor UV protection), lack of headroom, flimsy aluminum framework, and the poor sliding door design. Here are some alternative building techniques you can consider to turn the HF greenhouse into a real bargain.

1) Cover the polycarbonate plastic panels with 4-year 6-mil UV film.
2) Raise the roof of you greenhouse by nearly a foot using 2x12's, on edge, for your foundation.
3) Design your bench and shelving structure so that it doubles as solid support for the aluminum framework.
4) Hang the HF door on hinges rather than mounting it as a slider.

Sorry I couldn't post up all the pictures and instructions here but this link will take you to the step-by-step account of how I built mine.

And thanks to all the others on this forum who have offered up their own "tweeks" for this greenhouse. It can be a real bargain for beginning gardeners. Feel free to post up any questions you might have here in this thread and I'll try to answer them.

clipped on: 02.21.2014 at 09:29 am    last updated on: 02.21.2014 at 09:29 am

Aluminet shade cloth screen panels for HFGH

posted by: mudhouse on 09.28.2007 at 01:00 am in Greenhouses & Garden Structures Forum

I just replaced four polycarbonate panels on the south wall of my HFGH 10x12 with screen panels made from Aluminet shade cloth. I wanted to see if I could add ventilation and shade at the same time. (Click on any of the photos below for more detail.)

I used do-it-yourself window screen components (HD or Lowes.) You cut the metal frame pieces with a hack saw, and plug plastic corners into the ends. The screen is secured with spline pushed into the groove, using a spline tool.

I wanted to use the same glazing clips to secure the screen panels in the greenhouse frame, so I used the thinner 5/16" screen bars (not 7/16".)

I had to build two cross braces into each tall frame. Without the cross braces, the stretchy Aluminet bowed in the long sides of the frame (almost an inch on each side.) The cross braces are attached with (wimpy) metal clips purchased separately.

Aluminet has lines in the weave, and it stretches in the direction that�s perpendicular to the lines. In my screens the Aluminet lines ran vertically (the least stretchy way) but I think it would work in the other direction as well. It�s possible the cross braces wouldn�t be as critical if you installed the fabric so the most stretchy direction went lengthwise, instead of installing it like I did. Also, Aluminet has a seam every 7 feet, and one of my panels includes the seam. It worked fine.

I cut the cloth so it was about an inch larger than the size of the frame.

I ordered 40% Aluminet because some cacti and succulent nurseries I know use 40%, but now I�m worried I should have ordered 50%. I also suspect (20-20 hindsight) that stretching the Aluminet somewhat taut opens the fabric and reduces the density further�in other words, the 40% cloth in a relaxed shape would probably create more shade than the 40% installed in my screens. (Something to keep in mind.)

The 40% Aluminet was easy to secure with .140 size spline. I�m sure higher densities of Aluminet are thicker, but this material is so soft I think they�d still work. If it seemed too thick to fit into the groove, you could try smaller spline.

I trimmed the excess Aluminet with scissors, leaving about �" edge on the inside of the screen (I thought it might pull out if I trimmed it close.) This is how it looks inside the greenhouse.

I attached the Aluminet panels with the same glazing clips as the poly panels. I lined up the cross braces on the screens with the horizontal braces inside the greenhouse, thinking I might attach the screens with screws, using the holes I�d already drilled in the greenhouse braces for the poly panels...but the clips worked great by themselves.

I numbered the poly panels with a permanent marker before removing them. We didn�t carefully center each self-piercing screw, so I have to put each panel back in the same place to make sure it lines up with the screw hole in the brace.

I really like the clean appearance and the increased ventilation! I don�t have to worry about the Aluminet blowing off. Before installing these, the temperature in my new greenhouse was at least 130� with the doors and roof vents open; with these panels in place, it�s much closer to the outside temperature. Installing the exhaust fan and shade cloth on the roof should help more.

Of course, the downside is, summer rains will easily penetrate the screens. I�ll have to be aware of what I put on that side of the greenhouse. Annually, we have lots of heat and little rain, so I think it will be a worthwhile trade-off. I may add a clear plastic curtain on the inside of the south wall to be pulled into place during summer monsoon rains, if I don�t want my south bench to be drenched.

Here�s what happens when you don�t consider screen placement when doing your electrical. Although we used GFIC outlets and in-use outlet covers, I didn�t plan on the back of the outlet being exposed to rain. I�ll have to figure out how to weatherproof the back, or live with a baggie over that outlet in the summer.

These Aluminet screens are too porous to be insect proof, but I don�t care. I do need to keep birds out; the Thrashers poke big holes in my succulents.

When the night temps get cool, I�ll replace the screens with the poly panels. I tried leaving the screens in and putting the poly panels on top, but the combined thickness of the two layers won�t allow the glazing clips to fit in the channels, so I guess it�s one or the other.

The cost for each 6 �� tall screen frame was about $12 (not including the Aluminet cost.) Of course, once you pay for the screen, it would be easy to change the density of the Aluminet or install regular screening.

Anyway, in case others have considered trying this...that�s what I�ve learned!


clipped on: 02.20.2014 at 10:14 pm    last updated on: 02.20.2014 at 10:32 pm