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successful Season extenders

Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
Let's see if we can't keep on track with this thread:
What successses have you encountered with using green houses or season extenders in your efforts? This would include row covers, solar pods, cold frames, poly tunnels and greenhouses.


"There is enough in the world for everyones needs, but not enough for everyones greed"
(Buckman)
Jami McBride
volunteer

Joined: Aug 29, 2009
Posts: 1779
    
  10
Ha!  Nothing that official.... I, using my desk stapler, I staple clear plastic sheeting along the side of my house and then drape over my plant bed along that wall when night freezes are coming.  We harvested tomatoes 1st thing in December, enough from 4 plants to completely cover a bed.  We are still eating them as they ripen 

I also drape some plastic over my rabbit pavilion, which also covers my line of garlic growing next to the rabbit pavilion.  My garlic always starts to sprout over a month earlier than what is planted in other areas. 

So my 'extending' is very low key to say the least, but I am surprise every time how big of a impact it has.
                              


Joined: May 03, 2009
Posts: 461
Location: Inland Central Florida, USA
I can grow peppers as perennials in my greenhouse (well not really a greenhouse as it only has sides in the winter, otherwise it is a shade structure with plastic over the top, I'm not sure if they would survive as perennial without protection here.  I guess I'll see because I have one pepper growing without protection right now.


TCLynx
[url]http://www.tclynx.com/[/url]
[img]http://www.permies.com/permaculture-images/2692_740/Avitar.jpg[/img]
                    


Joined: Oct 23, 2011
Posts: 0
I made what I refer to as a "redneck greenhouse" by making a rectangle with straw bales and covering it with a pick up bed topper.  Put buckets of water in there too. Worked well enough to keep my baby seedlings alive through some very cold weeks in April.  An unexpected problem was rodents chopping down seedlings like they were trees!  So we took everything out and lined it with chicken wire, and that stopped that.  Man, was that frustrating though!  They didn't even eat them, the baby plants were just felled like little trees and left there.  !!!
Brenda Groth
volunteer

Joined: Feb 01, 2009
Posts: 4433
Location: North Central Michigan
    
    8
i have used coldframes and greenhouses to a great deal of success..there are many plants we couldn't grow in our climate without them..so if you want those crops..you use at least coldframes..greenhouses are less needed but i leave my  tomato and pepper and rosemary plants in my greenhouse all season..they are much better in the greenhyouse..i have tried both..and the ones outside of the greenhouse never produce as well, if at all and are very much smaller, stunted and diseased..

i'll keep my greenhouse.

we also cover outside plants in case of frost if they are at all tender, spring and fall..with whatever is handy..

and i also use slopes as season extenders..things planted at the top side of a slope will grow in a colder clmiate cause of the frost drain.

and we use sun traps here for both outside ...more tender plants..and for heat traps for the house to keep the house warmer..

where i have plants in my sun trap..take thehibiscus for instance..the ones in the sun traps grow twice as tall and have much more and earlier flowers than those in other areas of the garden.


Brenda

Bloom where you are planted.
http://restfultrailsfoodforestgarden.blogspot.com/
Brenda Groth
volunteer

Joined: Feb 01, 2009
Posts: 4433
Location: North Central Michigan
    
    8
oh i forgot, also we use windbreaks for our gardens..i have planted evergreen trees along our west property line to cut the wind and have a forest on the North..it makes a great deal of difference where the wind is controlled at how well the crops grow and produce.
Joel Hollingsworth
volunteer

Joined: Jul 01, 2009
Posts: 2103
Location: Oakland, CA
lapinerobert wrote:This would include row covers, solar pods, cold frames, poly tunnels and greenhouses.


How about cloches?

Or waterworks of the sort developed near Lake Titicaca?

Does hugelkultur count as a season extender?

Black-colored mulch? Hugelkultur? Or are those too multi-purpose?


"the qualities of these bacteria, like the heat of the sun, electricity, or the qualities of metals, are part of the storehouse of knowledge of all men.  They are manifestations of the laws of nature, free to all men and reserved exclusively to none." SCOTUS, Funk Bros. Seed Co. v. Kale Inoculant Co.
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
I was really looking initialy for coverings so cloches would be a season extender. But hugelkultur or as the french did piling manure/compost against cold frames would be an extender as well.
When you refer to Titicaca are you refering to floating gardens or some other form of waterwork?
What are you using as a black mulch?
                              


Joined: May 03, 2009
Posts: 461
Location: Inland Central Florida, USA
Explain how you would make Huglkulture work to extend a season etc.  I think anything is valid if you can help relate how it might help extend the season.  Especially if you have actually tried the method and can share how it did for you.
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
With a hugelkultur bed oriented on an East West axis the fact that it is raised alone would help in heat retention. Constructing a new bed I would slope the bed to better make use of southern exposure. Depending on the degree of decomposition of the woody mass/material heat from the decomposition could be a beneficial factor.

My hugelkultur bed was created by accident when the contractor that built my house several years ago piled dirt from the foundation over trees, a local woody pant called bitter brush and  wild currants that sadly had to be taken down for the house.   The axis of the bed just happened to be North-South. The pile is relativley tall, app 40 inches. 6 feet wide and 35 feet long.  It has served as my tiered potato bed for the last three years.  I use both sides for potatoes and cover them with spun cloth if it dips below freezing. Even with the N/S orientation it has been a productive bed for me.
Across the very top of this bed I have planted a combination of northlake currants and black currants. In our area currants are a reliable producer of fruit if you can keep the birds away.

At the end of my current bed I have a 10 foot diameter  5 foot tall piece of galvanized culvert buried 2 feet into the ground (purchased for one dollar at an auction) I have turned it into a fish pond, blue gills and goldfish, if they can stay away from the bluegills, last through the winter in the pond without supplying heat. I do run a 12 volt areator powered by a solar panel but it runs only when the sun is out and seems to be sufficient. Old moldy hay that a friend refused to feed his animals went around the culvert again tiered to the top and mushroom compost over the bales has been our herb garden. Hugelkultur style with the hay decomposing. It has slowly slumped but the addition of more soil and compost retains its tiered design.
From above I guess it looks like a big comet with a tail.
                              


Joined: May 03, 2009
Posts: 461
Location: Inland Central Florida, USA
I suppose my season extension goes in multiple directions.  I need to try to keep things cool in the spring so I can keep growing cool season veggies for more than two or three months of the year.  Aquaponics without supplemental heat and unprotected by any greenhouse will keep lettuce and other cool season crops growing through March and well into April here with a little shade yay!!!

I'm going to be testing out some frost blanket this winter to see if it will assist the potato patch through the frost/freeze season so we can actually get some taters before it gets too hot and they rot.

There is a nice hot sunny microclimate right in front of the house (facing south and it is a light colored concrete block house) where I've been growing a couple papaya plants.  They will freeze back during a really hard freeze but so far they have done ok this week through the cold.
Joel Hollingsworth
volunteer

Joined: Jul 01, 2009
Posts: 2103
Location: Oakland, CA
lapinerobert wrote:When you refer to Titicaca are you refering to floating gardens or some other form of waterwork?


As I recall, in this system plants are only ever a few feet away from water, and the trenches are never too very wide either. I understand they work partly by having such a large heat capacity, and partly by converting more sunlight to heat.

lapinerobert wrote: What are you using as a black mulch?


I don't currently do so. I've seen black plastic as a method for earlier production in several places, and I bet charcoal or partly-charred wood chips might be effective, too.
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
I don't remember any description of waterworks other than the floating islands, I do remember pictures of the boats and house were beautifully made of reeds.
Floating islands were common in some lakes for food production in South America.
Joel Hollingsworth
volunteer

Joined: Jul 01, 2009
Posts: 2103
Location: Oakland, CA
These are perhaps under-publicized. What follows is the best of my recollection, maybe not reliable.

I saw them on TV a couple years ago, at which time they had made news. Some archaeologist filled them with water to see what they did (they were not set up in a way that made sense, based on surviving agricultural practice: too many to be for irrigation, to small to be for transportation; they were written off as spiritual or regarded as un-explained).

Once there was water in them, it was apparent that they did a good job of preventing frost. At which point the size of the settlements made much more sense: the current, much smaller, population struggles to subsist even with some food trucked in by fossil fuel.

The project then became a combination of archaeological/anthropological research and farm aid.
Mike Turner


Joined: Sep 23, 2009
Posts: 154
Location: Upstate SC
    
    1
I cover most of my beds with cold frames/mini-greenhouses.  Here in upstate SC, I am at the same latitude as Los Angeles and, as far as the winter daylight goes, I should be able to grow any of the cool season winter crops that they can in SoCal.  The trick is protecting the crops from the occasional blasts of cold continental air that blow through here from time to time during the winter (we are currently getting one now).  My cold frames keep my beds productive through the winter growing cool season crops and on mild winters allow me to produce a winter potato crop.  They also let me get an early start on growing the heat loving summer crops and self sown current totatoes usually start producing by mid May.  Also they extend the tomato and pepper season into Dec in the fall.  Without them my beds would be mostly dormant from Dec through Feb, serving mainly as a storage bank for root crops grown during the previous growing season.
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
I lived just outside Hilton Head for a few years.
It was such a drastic change from Wyoming where I grew up.
  I had a cucumber vine that crawled up to the top of my TV anttennae in my first garden there. Have a lot of good memories from SC. Funny I was looking at my shrimp cast net from those days in the garage as I came in tonight wondering why I still keep it.
                          


Joined: Jan 17, 2010
Posts: 31
For starters, as a brand new member, let me say that this site is unbelievably great !  It's also good to know that there are so many people out there who actually share my passions and priorities re what you call 'permaculture'.

Now back on topic ...

Since I live in northern NY, where it's fortunate to get a frost free 90 day growing season in many years, 'season extenders' are a must if you don't want to be locked into a relatively small selection of natural short season heirloom vegetable types or short season hybrids.  Over the years my family has tried a ton of potential options to stretch the growing season.

On the inexpensive side, the best option seemed to be row cloches ... which basically will 'buy' you two extra weeks of growing season by allowing you to transplant about 2 weeks prior to the normal 'last frost' date.   The primary help comes from the cloche allowing the earth temperature under it to heat up and stay warmer, with secondary help being protecting transplanted seedlings from direct frost exposure.

However, if you SERIOUSLY want to extend the growing season to the point of a major productivity increase, there is no substitute for a greenhouse !  A couple of years back I invested in an 8ft x 16ft RION 'plastic' greenhouse ... which successfully extends the growing season in northern NY from 90 days to at least 120 days ( with a tiny investment in auxiliary heat).  This opened the door to growing a much wider variety of heirloom veggies, and also resulted in harvests per plant which were nearly twice that of the same plants grown in an open garden.

Paul Cereghino
volunteer

Joined: Jan 11, 2010
Posts: 847
Location: South Puget Sound, Salish Sea, Cascadia, North America
    
  14
I grow most of my yield in 4' wide intensive raised beds.

CLEAR PLASTIC - I frequently put scrap of clear plastic on the surface of a bed, and plant on a seam or though a hole.  It gets soil temp up faster in our cool climate so I can grow melons and the like.  I figure clear plastic works best because the IR energy passes through the plastic and is absorbed by the soil, rather then having the IR absorbed by the plastic itself.

ROW COVERS - I've started experimenting more with row covers.  I don't like them because they are disposable, though I am getting 4 seasons from the cheap materials.  Jury's still out.  We had a week of weather in the teens at night, and everything but the cabbage got hammered... event the tops of Kale and favabeans died off... discouraging, but unusual weather for us...(what's with the frozen ground?!?!)

TEMP PLASTIC GREENOUSE - I pound 2 to 5 foot lengths of rebar every 3 or 4 feet on either side of a 4 foot bed, then connect them with arches of 1/2 inch PVC, then put a sheet of plastic, screwing a cedar 2x2 on either edge to facilitate rolling up an edge for access, and to hold down the sides, clipping the ends closed with stationary store bought 'bulldog clips' to clip close the ends of a plastic tunnel.

MOVABLE PLASTIC GREENHOUSE - 4x6 foot 2x2" cedar box with PVC arches, and plastic stapled.  Pick it up move it where you need it.  Its OK, but when the garden gets full I get annoyed

THE FUTURE - I think I'm heading towards movable 2 bed-wide greenhouses 9'x12' with enough headroom to grow indeterminate tomatoes from the rafters.  This is because both me and Martha Stewart have been inspired by Elliot Coleman's new book 'The Winter Harvest Handbook'.  He year round on the Maine coast with unheated mobile greenhouses.  And has a good practical style.  Get your local library to buy it.

http://www.fourseasonfarm.com/books/index.html#handbook


Paul Cereghino- Stewardship Institute
Maritime Temperate Coniferous Rainforest - Mild Wet Winter, Dry Summer
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
I like Colemans books and have begun to utilize his double coverage in my stationary greenhouse this year as an experiment.
It seems to be a successful venture so far but it has been an unusually mild winter here despite a few days of 26 below zero. Cabbage, leeks,claytonia corn salad, carrots all seem to have done quite well parsnips greens have faded but I have overwintered them in the past and they begin growing again once it warms up.
I have plans for an improved larger greenhouse this year and will adapt some of his suggestions into my model.
paul wheaton
steward

Joined: Apr 01, 2005
Posts: 14987
Location: missoula, montana (zone 4)
    ∞
A 2 foot tall raised bed added two weeks onto either side of the season.  So four weeks total.  I have done this in four different places with excellent results.

Mike Oehler's greenhouse - which is very different from other greenhouse designs, was pretty rough shod, with lots of room for improvement ... AND ... he could reliably keep tomatoes in there until mid december in north idaho without adding heat. 

It would seem that if you took oehler's basic designs and added some of the wofati stuff to it, you could raise tomatoes as a perennial.


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Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
I have traditional raised beds but in addition have a set of three that I have southernly sloped @15 degrees to boost solar gain.
A friend has an underground greenhouse greenhouseglimpses.blogspot.com and it is something that I would like to try in the future.
paul wheaton
steward

Joined: Apr 01, 2005
Posts: 14987
Location: missoula, montana (zone 4)
    ∞
lapinerobert wrote:
I have traditional raised beds but in addition have a set of three that I have southernly sloped @15 degrees to boost solar gain.


Ooooooo .... I like that .... 

Oh - and some folks are mentioning hugelkultur or compost for heating a raised bed.  I suppose you might get some value out of something like that if you built it in the spring, but you would have to put lots of dirt over it so that the baby plant wouldn't get too much N early on.  And it would be pretty cold come fall. 

Overall, I cannot help but think that these are not worth the effort.   

And, on top of that, I once had some dumbass spend way too much time trying to convince me of it.  He read it in a book somewhere.  And frankly, I think the author of that book must be a dumbass.  But this guy's position was that since I don't have a book on the subject, I must be wrong and the dude with the book must be right.  So now I have a sort of knee-jerk-reaction to the whole idea, which I recognize as irrational, so I'm trying to suppress it.  (now I have my dander all worked up .... that weasely dumbass  ... lying bastard ... icky twit ... i shoulda kicked him into next week ... )

                          


Joined: Jan 17, 2010
Posts: 31
^^^ agreed that the 15 degree angle idea for raised beds is something that is definitely worth trying ... especially in my northern climate !!!


in regard to theoretical attempts to pull off a year-round greenhouse in northern climates without auxiliary heating, ultimately this seems to come down to an inescapable trade-off.  Every square foot of 'glazing' that provides the photons which plants need during the day also loses a huge amount of heat at night.   And no amount of thermal mass can passively boost temperatures above the long term average.   Thus at some point of northern latitude / northern climate, the intensity and hours of available sunshine is simply insufficient to sustain minimum levels of light and minimum overnight temperatures needed for plants to remain productive.

This isn't to say that there aren't auxiliary heating and / or auxiliary lighting options available that aren't in keeping with with the basic tenets of permaculture.  However, none of these appear to be 'cheap' or 'simple'.  Thus until new and better options present themselves, I'm approaching permaculture for northern climates as an inescapable annual seasonal cycle ... where the ability to gain a few extra weeks of growing season via relatively 'cheap' and 'simple' measures is as good as it gets for now.
paul wheaton
steward

Joined: Apr 01, 2005
Posts: 14987
Location: missoula, montana (zone 4)
    ∞
Melonie wrote:
And no amount of thermal mass can passively boost temperatures above the long term average.


Have you read the wofati article?  I think having a higher annual average is what I was proposing.

                          


Joined: Jan 17, 2010
Posts: 31
^^^ yes, briefly.  However, in northern climates, you're still facing the issue that surrounding soil temperatatures are going to drop to 32 degrees to a depth of 3-4 feet ... and that snow buildup on an earthen roof is going to preclude solar warming.  You're then facing a situation where several cloudy winter days in a row will create a 'drain' on the temperature of the thermal mass.

But agreed that in slightly warmer climates, where solar warming of the earthen roof would occur year-round and where frost wouldn't penetrate surrounding soil anywhere near as deeply, that this approach could be a very viable concept.
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
What I am using in my greenhouse, which is comprised of three long raised beds, is double coverage over the beds, poly tunnels as described by Coleman.
  Experimenting with spun fiber over the top of the poly and am even using mylar over one bed in addition to the poly cover to reflect back any gain acheived during the day. When I go out to feed the animals I  step into the green house and cover in the evening and in the morning roll it back only takes a minute.
I do have a hundred gallon water resevoir in the green house that is used for hydroponics in the summer and a heat sink in the winter with a thermosiphon set up.
Travis Philp
volunteer

Joined: Dec 28, 2009
Posts: 951
Location: ZONE 5a Lindsay Ontario Canada
    
    8
I know a grower close to me who grows salad greens all year round in an unheated stand-alone greenhouse with no thermal mass additions on the inside or outside.

She uses a standard hoop house and floating row covers over the greens themselves. I wonder what she could get away with by adding some water barrels and growing container plants on them, or heating with compost among other passive means...


http://www.greenshireecofarms.com
Zone 5a in Central Ontario, Canada
                          


Joined: Jan 17, 2010
Posts: 31
know a grower close to me who grows salad greens all year round in an unheated stand-alone greenhouse with no thermal mass additions on the inside or outside.


Again the 'all year round greenhouse' equation isn't simply a matter of average winter temperatures i.e. growing zone.  A HUGE part of the equation is the number of actual days of bright winter sunshine available ( or consecutive number of days without it).  Another HUGE part of the equation is worst case sustained overnight heat loss ( which is a function of low overnight temperatures plus wind etc.).  Both of these vary tremendously with specific locations and weather patterns.   

An interesting read in this regard can be found at http://aes.missouri.edu/swcenter/research/Solar-heated%20greenhouse.pdf

I do have a hundred gallon water resevoir in the green house that is used for hydroponics in the summer and a heat sink in the winter with a thermosiphon set up.


No matter what sort of thermal mass is actually used, i.e. water versus earth versus adobe / brick, haveing enough thermal mass available to 'ride through periods of cloudy days and/or cold nights appears to be a not-so-secret ingredient for success.  I also have a couple of hundred gallons worth of water as thermal mass in my own greenhouse ... and wish I had the space for more.

Your thermosiphon idea sounds interesting ... especially if expanded to actually heat the soil in the growing beds somehow.

Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
Fortunately my area has a 300 day of sunshine average.
The equation also has to take into account what you are growing . I know I can't grow peppers or tomatoes during the winter so I rotate cool weather crops into the green house in the beginning of fall or as fall comes to an end. Though the ground under my greenhouse does get cold it never freezes to the depth of 3-4 feet even though it is frozen in my uncovered beds adjacent to the greenhouse.
With the double coverage of the raised beds in the greenhouse those beds didn't freeze at all even though we had some extreme low temps this year.
With limited extra effort, covering and uncovering the secondary poly tunnels with spun row covers, cold climate greenhouses can produce reliably if you have sunshine.
                          


Joined: Jan 17, 2010
Posts: 31
Fortunately my area has a 300 day of sunshine average.


^^^ insane jealousy attack LOL !!!  My area is below 180 days / <50%

http://www.ncdc.noaa.gov/oa/climate/online/ccd/pctposrank.txt
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
Yikes! I'd go crazy with only 165 days of sun, I get grouchy once the days start to get shorter.
Jennifer Smith


Joined: Jul 14, 2009
Posts: 669
Location: Zone 5
Joel Hollingsworth wrote:
These are perhaps under-publicized. ..
Once there was water in them, it was apparent that they did a good job of preventing frost. At which point the size of the settlements made much more sense:


What were they?
Robert Ray
volunteer

Joined: Jul 06, 2009
Posts: 1321
Location: Cascades of Oregon
    
  12
The Titicaca agriculture is in this article kinda interesting.

  www.sas.upenn.edu/~cerickso/articles/Exped.pdf
                                      


Joined: Jan 01, 2010
Posts: 172
Location: Amsterdam, the netherlands
    
    1
Hi all,

im sorry if i post a lot in maybe not the best places, im am still getting to know the forum.

we are using stone/rock a lot as season extender here. it isnt a greenhouse like structure, so maybe the wrong thread...

We ar in amsterdam, which is a temperate climate due to a mild sea breeze all year. so mild winters mild summers. but it can still freeze about -15 degrees Celcius, with snow and ice and stuff. the growing season is quite ok, but young sprouts sometimes die cos of late frost.

also we are in a city, and into urban PC. so we work with rock and discarded bricks buried in the soil. We have build a straw-berrie tower, i dont know why its called like that because all the ones ive seen got vegg and herbs in them but anyway.



it works a little bit like a herb spiral, but since its mostly stone surface it warms up early in the year, and we can keep harvesting from it a good 1,5 month longer than in our raised beds. almost everything gets bigger if it grows in the vegg. tower. tomatoes, kale, herb.

according to our pdc teachers the advantages are:
more soil volume than a raised bed that takes the same ground surface.
more growing surface than a raised bed on the same ground surface.
more different microclimates, sun, shade, half-half.
warms up due to the bricks.

at our website you can find some more about it, like fotos of building it:
http://swompenglish.wordpress.com/vertical-gardens/


land and liberty at s.w.o.m.p.
www. swompenglish.wordpress.com
                          


Joined: Jan 17, 2010
Posts: 31
Joop, from an aesthetic point of view your 'tower' is a work of art !

Also it is easy to understand how the reduced ratio of surface area to total thermal mass of your 'tower' would do a great job of retaining heat / maintaining a higher soil temperature at the plant roots.

Drainage would obviously be excellent as well

And the construction costs involved are next to nothing ... some concrete patio blocks or bricks

You've convinced me to try building conceptually similar but simplified 'towers' using much larger blocks and fewer levels in my own outdoor garden this coming spring, if for no other reason than to see how well it does 'riding through' my multiple day stretches of cloudy skies and low air temperatures. 

Specifically, I'm thinking of trying your 'tower' concept for 'three sisters' ... corn on the top, with bush beans planted in an upper 'ring' and summer / zucchini squash planted in a 'lower' ring.
Travis Philp
volunteer

Joined: Dec 28, 2009
Posts: 951
Location: ZONE 5a Lindsay Ontario Canada
    
    8
I'd say you posted in the right place Joop.

That spiral of yours...It's making me think that maybe I could use the 100 or so concrete blocks I have in the same way as you used your bricks. The beauty of the concrete blocks would be that I could plant right in them due to the three holes in each block and therefore not lose as much surface area to the blocks.
Jennifer Smith


Joined: Jul 14, 2009
Posts: 669
Location: Zone 5
Isn't it great how the threads overlap much like permaculture it's self.  Such a wealth of knowladge on the permie site!
tel jetson
steward

Joined: May 17, 2007
Posts: 3088
Location: woodland, washington
    
  53
I hate it, but we use black plastic mulch to grow basil and peppers.  works like a dream.

we built a couple of metal-framed hoophouses (some folks call them high tunnels) covered with polyethylene.  they're both 20'x95'.  they're mostly for tomatoes, but we grow lettuce in them when it's too cold for tomatoes.  we might put more work into them to keep them warmer over the winter, but we've already built them twice because of a nasty flood last year.

we started with pvc hoophouses, but I'm glad we've ditched those.  they were fast and cheap to build and relatively effective, but I have a special place in my heart dedicated to hating pvc.  pvc is nasty to manufacture and dispose of, degrades quickly in sunlight, reacts with polyethylene, and doesn't hold screws very well.

metal hoops are surprisingly cheap from greenhouse suppliers.  Oregon Valley Greenhouses quoted me something like $34 for a stout metal hoop sixteen feet in diameter.  five of those would be enough for a 20'x16' hoophouse.  UV-stabilized polyethylene to cover it might be $100.  some additional hardware to attach the plastic and you've got a sturdy greenhouse for a few hundred dollars.  save some of the money you make selling produce to buy polycarbonate when the polyethylene starts falling apart after a few years and you'll be even sturdier.

Thus at some point of northern latitude / northern climate, the intensity and hours of available sunshine is simply insufficient to sustain minimum levels of light and minimum overnight temperatures needed for plants to remain productive.


I'm interested in using a sort of solar closet to heat a greenhouse in combination with some of Mike Oehler's ideas and maybe some of Paul's.  if the thermal mass is large and gets exceptionally hot during the warm season, the average air temperature becomes less important.  I'll probably use triple-wall polycarbonate, with an R-value of 2.4.  not great, but better than poly film.  I'll add critters for some more heat.  maybe ponds south of the greenhouse to reflect light into it.  could be a disaster, but I'll risk it.


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get stung! beehives
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Joel Hollingsworth
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Joined: Jul 01, 2009
Posts: 2103
Location: Oakland, CA
Jennifer Smith  "listenstohorses" wrote:
What were they?


I think the language that included a name for them has gone extinct, along with the larger system of agriculture they were a part of.



Hydraulic albedo/thermal-mass season extenders? It might be worth thinking up a new name.
Joel Hollingsworth
volunteer

Joined: Jul 01, 2009
Posts: 2103
Location: Oakland, CA
paul wheaton wrote: I think having a higher annual average is what I was proposing.


I think the comment was talking about the average within the greenhouse: obviously, the thermal mass won't release more BTUs than it has absorbed (unless it's radioactive or something).
 
 
subject: successful Season extenders
 
cast iron skillet 49er

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