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Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 5:36 AM

Hi all.

In New Zealand a couple months ago I built the prototype for a very cheap, easy, high volume and reasonably portable greenhouse design, largely intended for use in urban type environments.

Details here:

http://urbangreenhouse.blogspot.com/2011_06_01_archive.html

And for the last month or so I've been in Paris looking to set up a collective project with the aim of growing large amounts of food within the city.

The biggest problem we've had has been the plastic. In NZ I was lucky enough to get a good deal from a local garden supplies store, but even then it constituted two thirds the cost of the entire project. Here in Paris it's more like 80%, and we'd have to travel 100 km out of the city to get even that.

The original idea for the greenhouse design was to use plastic mulch or construction film, but they break down in sunlight in a very short time; weeks to months. I've looked into other sources of plastic, preferably something mass produced and ideally disposed of.

Any ideas? It only needs to be something easy to get hold of, be able to last even only 6-12 months outside, and let at least 30% light through.

Being able to source this would make this project and urban farming as a whole vastly more viable.

Cheers,

Daniel.

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#1

Re: Cheap and available alternative to greenhouse plastic for use in urban farming?

08/01/2011 6:47 AM

i've pondered on this myself. i use pvc water pipe for the frame and use 1 x 4" cross slats with banding material for stiftening the frame. the plastic covering is the major problem. i've noticed that solar covers for swimming pools seem unaffected by solar rays, but of coarse they're not suitable for a green house.

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#2

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 12:47 PM

You want to check out the greenhouses in Southern Spain! All plastic (apart from the metal or wood struts and supports) I would hate to see these go into production in other places! There is a google map of 'El Ejido' and all you can see is plastic greenhouses for as far as the eye can see. They are the most ugliest monstrocity I have ever seen! The main problem is the plastic! (believe me, they have tried all sorts of plastics and they all fail after a year or two in the sun!) You could change the plastic easily but knowing how lazy people are, they will just dump the old sheets behind a bush or in a river and slowly but surely, the place you introduced these new plastic greenhouses will turn into a dump unless you can solve the disposal problem by offering to collect the old and supply the new at a cost which is cheaper than your competitor otherwise it's 'Hello El Ejido'

Sorry for the little rant I do wish you the best for your venture so check out suppliers of plastic sheet in S.Spain.

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#24
In reply to #2

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/09/2011 11:32 AM

Thanks for your reply. Your concern for safe and environmentally friendly disposal of plastic of any kind is well founded. We have a solution. It's called "biomass gasification". We can "Gasify" most anything that is not mineral or metal without combustion and make enough electricity to power our operations. We also draw from a community's municipal waste reducing their need for landfills. We introduce recycling programs for those components we're not able to Gasify. We can also use processed Sea Water to grow our crops. As long as we're generating our own electricity, this is economically feasible. We create a sustainable life cycle while cleaning up the environment.

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#26
In reply to #24

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/17/2011 4:39 PM

Yeah nice one.

What's involved in gasifying plastics? Is it methane that you get, and how much compared to organics?

I can see gangs of street urchins scouring the city for plastic waste to fuel their community gasifiers...

And how are you desalinating?

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#3

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 5:51 PM

Have you considered "silage wrap" as used by dairy farmers?

This is like "cling film" food wrap, but comes in around 900mm wide spools. It is weather proof (as the silage bundles are stored in the weather) and recyclable. There is usually a faing green tinge to the material.

It is also cheap and readily available as the farmers use heaps of it. Like cling film, it doesn't tear easily, but rather stretches in both orientations.

Similar material is used to secure pallet loaded materials for transport companies, and than material is clear.

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#4

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 6:11 PM

@Truman

It's not so much production as trying to develop an open source model for urban food production. It's not meant as a business, just a toolset that people can adapt and start growing their own food.

Disposal of plastic would be a problem, yes, which is part of the reason I'd ideally like to use some kind of waste material. The rest of the greenhouse is pretty much just scrap wood.

And yeah, I've seen that area in Spain. Ye gods that's a lot of greenhouses. An eyesore they may be, but it is a very good way to grow food...

@Just

I checked out a couple of those industrial wrap style things, but people I spoke to seemed pretty sure it wouldn't even last a couple of months. But there might be specific stuff, like the silage wrap, which is made a little more robustly.

Do you know how long it's likely to last?

Also, stretchy isn't really ideal, as the construction of the greenhouse design requires putting the plastic under some tension.

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#5
In reply to #4

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 6:21 PM

Looking into silage wrap, most of it seems uv treated and guaranteed for twelve months, which is actually pretty good.

Problems tho are that it is stretchy, and doesn't seem to come in clear. Only white, black and green.

Wonder how much light the white transmits?

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#6
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Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 8:13 PM

Maybe you could consider something other than plastic. For example the Reemay fabric or similar is more durable than plastic and it doesn't become shreds of impossible to retrieve garbage. Yes it's white but admits around 70% of light. Manufacturers will specify how much light gets through specific products. (I'm using it for shade cloth at the moment).

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#7

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 11:17 PM

http://www.agriculturesolutions.com/Sun-Selector-Greenhouse-Plastic/View-all-products.html?gclid=CKT3j43Rr6oCFQsS2godT0-u_Q

My cousin in Indianapolis uses this stapled to both sides of a wooden framework made out of 3/4" wood and inflates the two layers with a 12 volt boat blower connected to one side of the two layers creating an insulating 3/4" thick double layer of plastic drawing air from the warm inside.

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#8

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 11:24 PM

The light transmission through a single thickness of silage wrap would be adequate for Aus and NZ conditions. (I've grown vegetables inside a "portable carport" using the white fabric cover with great success.)

There is a clear version used by transport companies to wrap and waterproof their pallets. Just like cling film. I've only ever seen this in 450 wide and do not know of its UV properties.

The silage wrap is able to be recycled and is actively recovered to be re-processed into other items.

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#9

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/01/2011 11:51 PM

BHV 55 Rue de la VerrerieParis, France 75189

www.bhv.fr

Building products section, specifically the masonry isle for clear 6ml plastic in long rolls.

recyclable.

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#10

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 4:40 AM

Hey, thanks guys, some good info here.

@artsmith

That stuff actually looks very interesting, it's cheap and seems fairly durable. Repels water but is porous. I'm not sure letting some air through would be such a bad thing tho, might help with oxygen buildup and wind. Shouldn't greatly affect temperature, I guess. I'll look into this.

@129C

That film looks pretty good, and the price isn't bad either. Matter of general availability tho. We had a good look round here for similar stuff and did find some, just that it was pretty expensive and out of the city. Other than that it would've worked fine.

I like the idea of an inflated double wall, but for urban growing one of the key factors is mobility. It's only a matter of time until you lose permission to use whatever land you can find, so need to be able to pack up and move at pretty much a moments notice.

On the subject of heat regulation, I was thinking of something like what I prototyped in Australia:

http://cr4.globalspec.com/thread/67521

For the masonry plastic, any idea how long it would last? I might go check, as it's local..

@just an

Ok, good to know about the silage wrap. I would be needing something that doesn't stretch tho, and it sounds like this stuff is specifically designed to do so.

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#16
In reply to #10

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 1:00 PM

I don't know about France, but Reemay is widely used by farmers here in Canada as a season extender. It allows moisture and light to enter but does provide some warmth as an enclosed space - different weights are used depending on how much heat you want to capture. It is also laid right over the plants as a pest control barrier.

When it's used on the ground it gets dirty and torn at the edges - and this is where I got my shade cloth, for free. My friends are running an organic farm and use the stuff extensively on very long rows, and they were discarding bags of reemay after 2 or three years service on the ground. I picked through the bags, found less torn parts, cut useable sections, and washed it out - came clean and white, perfect for my application.

So where money (more than labour) is a factor, you might look into the local usage of this or similar material by farmers, see if you can get the used material free, and wash out, fix/ re-use the discards.

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#11

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 4:43 AM

what about transparent polycarbonate???

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#12

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 7:18 AM
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#13

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 7:34 AM

Raised on a farm in Vincennes, Indiana we used green houses every spring to start plants then later transplanted them to the fields. We used a heavy plastic film purchased from our local Farmers CO-OP. I do not recall the mil thickness. A yahoo search yields a vast array of suppliers such as this one http://www.greenhousemegastore.com/category/plastic-greenhouse-film

The best green house my grandfather ever built was made like a pole barn. He covered it with clear fiberglass corrugated panels on the roof, sides, and ends. Then he filled the floor with pea gravel for drainage. It was expensive but had next to no maintenance. It was constructed some 25 to 30 years ago and still in great condition.

If you want portable then you might consider building your cold frame green house on a wagon or trailer. We did this with all of our farm wagons as we were going to transport the plants to the field for final planting anyway. A 2 x 4 mounted vertically on each end is joined/braced with a horizontal 2x4. Then the plastic cover is attached to one of the wagon sides and then rolled over the cross brace to the other side. There it is attached to a 2x2 that extended beyond the wagon bed by a foot or so on each end and provided a handle. This side was allowed to just hang there and was not mounted or attached to anything other than the 2x2. When you want to uncover the wagon one person on each end rolls the plastic up on the 2x2. The roll is laid on top of the wagon against a couple of wood slats to keep it from being knocked off on to the ground. The wagon sides were made out of 2x10's or 2x12's so plenty of room for the seedlings.

Are you using your green house to just start the plants or are you wanting to use it for the entire growing season?

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#14

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 8:14 AM

@ Mohamed

Definitely looking for something flexible, so when the whole thing is taken down and moved, probably once or twice a year, maybe more, panels can be rolled up and easily transported.

@129C

Nice pdf. Some good info in there.

@The Mechanic

Those prices are pretty similar to here in Paris. It's doable, but would be a lot moreso at about half that.

Regarding trailered growing spaces, yes that is an option, but I was wanting to make these things pretty big. It's not ten times the cost or work to make something ten times the size.

http://urbangreenhouse.blogspot.com/2011_06_01_archive.html

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#15

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 10:40 AM

Not that it's ugly or anything...but it looks like the old Cheepee Teepee I used to see in Mother Earth News...anyway...check out this link for someone who is like-minded, she apparently had issues with zoning:

http://www.dailytribune.com/articles/2011/07/12/news/doc4e1c43e84305e443511356.txt

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#17

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 5:41 PM

While away from the site overnight, I remember another greenhouse that I saw on a local tour. They use "geotextile" fabric as the liner. Comes in 3m wide strips, allows air exchange and also readily available.

Good luck, but given the resourcefulness of people prepared to look after a garden, they will often find materials that we haven't even considered.

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#18

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 6:04 PM

Geotextiles ayy....

They look interesting, but yet to see any numbers on transmissiveness and UV resistance. They are meant to go in the ground...

How was it working out for those you saw using it? Any idea which particular type they were using?

Also, is air exchange likely to be a good thing? It won't hamper the heat retention too much?

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#19

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/02/2011 11:22 PM

The geotex that was used had been in place for 12 months and was being used primarily for seed raising location. Light intensity here is reasonable and the plants in there did not seem "leggy". We were told the geotex was effectively fibers made of molten stone and so weathering would naturally occur, but the material has no "grain" and thus tears do not propagate and could be patched.

As far as air exchange and temperature retention, local winter conditions would bottom at -2 overnight with around 60 frosts per year. Winter daytime ambient is around 18, so we don't face the challenges that others need to consider.

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#20

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/04/2011 5:29 AM

12 months is plenty. As I say, the aim is to have a highly mobile distributed farm, with greenhouses being taken down and relocated maybe a couple times a year. So as long as the process of replasticing them is not too much work, it doesn't really matter too much if the plastic itself doesn't have the longest shelf life.

Geofabrics and Reemay I think are two very solid leads on this that I'll be chasing up in Ireland.

Man, it's going to be such a luxury actually being able to speak the language...

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#21
In reply to #20

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/04/2011 8:09 AM

Oh Man, are you in for a suprise with the Irish accent LOL!

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#22
In reply to #21

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/04/2011 9:05 AM

Yeah, I've been there before and three years in Scotland, it always takes a while get to get my ear around it. On the bus to Dublin the first time it literally took me a couple hours to realise they were speaking english. I thought it was Gaelic...

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#23

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/08/2011 7:03 PM

Daniel - Sounds like I'm doing the same as you i.e. designing 17ft x 100ft Urban Greenhouses which can be easily fabricated and assembled. I'm using PVC Piping and sheet Polyethylene (by the roll) cover obtained, in most part, from local sourcing. We're also providing equipment and training and supervision for sustaining the operations.

We're using hydro and acqua-ponic technology to get ten to twelve fold yield of "better than organic" produce a year in any climate. If our "Polyethylene" sounds like what you need, I'll research Global availability and pricing. RFH 8.8.11

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#25
In reply to #23

Re: Cheap and Available Alternative to Greenhouse Plastic for use in Urban Farming?

08/17/2011 4:10 PM

I think maybe PE was what we were using in New Zealand. Seemed pretty good stuff and we got a decent deal on it. Is the sort of thing we tried to source in Paris, I think it was some random local unavailability meant we couldn't find it in the city or quite cheap enough.

Interested in your setup? Where are you based? Got a website?

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129CBRider (3); artsmith (2); cuba_pete (1); fredhoward (2); jlstitt (1); Just an Engineer (4); Mohamed Wahab (1); Mr. Truman Brain (2); sugarandfat (9); The Mechanic (1)

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