Greenhouse

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Greenhouse building

The Greenhouse Size

Choose the Right Size. The larger the greenhouse, the better its ability to buffer temperature extremes. That’s because a larger greenhouse will have a larger amount of thermal mass — in the form of soil — that is warmed by the sun during the day, resulting in warmer nighttime temperatures. Another reason to choose a larger greenhouse is that you’ll find more and more things you want to do with it.
My initial plan was to erect a 20-by-32-foot greenhouse, but I found that by purchasing the 20-by-48 stock size, I picked up 50 percent more growing space for a mere $100.

The Greenhouse Structure

Start With Simple Components. Most greenhouses are made from sheets of plastic stretched over a metal frame. Mine is a Paul Boers “gothic” style kit (the arches come to a peak at the top, which is better for shedding snow). I paid more up front to get 1 1/2-inch galvanized steel pipe, rather than 1-inch, for added strength.
Protect Your Foundation. Install a single course of 4-inch hollow concrete block on a small poured footer, then lock a better grade 2-by-4 (sealed against moisture) onto the top of the block foundation using J-bolts pushed into wet concrete in the holes of the blocks. The channel lock is still screwed into wood, but the wood is never in contact with earth or rain. With applications of sealant as needed, it should last as long as I do.
Brace for Winter. If you live in an area that gets snow, brace the hell out of your greenhouse! I put up 2-by-4 vertical braces to add support to the framing from the earliest possible date for snow in late fall until the latest possible date in early spring.

The Greenhouse glazing

I also recommend using 6-mil plastic that has been treated to resist ultraviolet breakdown. I use two layers of plastic with a small, energy-efficient blower to inflate the space in-between. The inflated “bubble” increases the insulating value of the cover, sheds snow more readily, and resists “chatter” in the wind, resulting in better wear.

Vinyl sheets: Lasalle canvas and ropes; 514-366-2800 (5’large x 3’long = 1 verge = $6.50; W1247 – 7oz)

Ventilation

Provide Adequate Ventilation. If you plan to grow vegetable crops in the greenhouse during the summer, your greenhouse will need large vents in front and on top or heavy-duty exhaust fans and roll-up sides. For most winter growing, however, exhaust fans are superfluous. I know growers with 20-by-96-foot greenhouses who report that winter ventilation is adequate just by leaving the doors open as needed.

Soil

Never add nitrogen fertilizers in the greenhouse, and I always use plant-based rather than manure-based (higher in nitrogen) composts. I am even concerned about the nitrogen added to the soil by my summer cowpea cover crop, and plan to follow it with a quick mixed grain cover to “sop up” some of that excess nitrogen before I plant other crops.
There are three benefits derived from keeping chickens in the greenhouse in winter: C02, heat and de-pesting.

Irrigation

Know When to Water. It’s best to water deeply from time to time in lieu of frequent shallow waterings. Water in the morning. Avoid overwatering, which makes plants “sappy,” less able to withstand cold and other stresses, and less flavorful and nutritious as well. Test the soil with your finger: As long as you feel good moisture half an inch deep or so, it’s better not to water.

More info


Greenhouse heating

Soaring Raven Laboratory (SoaringRavenLab at gmail dot com)

SRL, Soaring Raven Laboratory, is located in south central Colorado at an elevation of 7,000 feet above sea level. The high country climate has dry warm summers with daily temperatures in the upper 80’s to low 90’s followed by long snowy winters.
The lab was built around a self-contained 12’ x 24’ greenhouse that has the ability to obtain all of it energy requirements from the sun by the integration of both passive and active solar energy systems. It was constructed in the late fall of 2013 and became operational in December of that same year on the winter solstice.
The electrical power to operate the labs ventilation, circulating pumps and lighting systems comes from an array of solar panels.
While inside temperatures would hardly be balmy in the greenhouse, plants would still be safe from freezing. The internal air temperature dropped to 1C (34F) when the outside temperature plummeted to -27C (16F).

At the lab we are currently testing a simple low cost hot water collector to boost the amount of passive solar energy that’s being stored in the 300 gallon thermomass water tanks. Instead of using rigid copper pipe in the collector we are incorporating cross-linked polyethylene tubing, commonly called PEX or XLPE which is used frequently in domestic home water systems.greenhouse water battery bank

The advantage of using PEX is greatly reduced cost, as much as 75%, over the use of copper. PEX does not as effectively transfer heat from the sun into the water that is circulating through the system as does copper. When exposed to sunlight PEX piping can degrade. To counteract this effect the UV is being filtered out in our collectors before coming into contact with the tubing.

The PEX hot water collector is basically a loop of continuous tubing, perhaps a hundred feet long, snaking through a long shallow rectangular box painted black and covered with a sheet of polycarbonate. The PEX is connected to a low speed 200 GPH pump submerged in the thermomass storage water tank. As the water circulates through the loops it’s heated by the sun. The pump is controlled by a thermostatic sensor located in the solar collector. The end result is the water in the tank stores the additional heat that in turn is released back into the greenhouse as needed.
greenhouse inside 1In November, 2014 the PEX solar panel added 523,168 BTU’s (British Thermal Units) to the test tank. This energy was released back into the greenhouse in the form of radiant heat.
During the month there were 6 days of fully overcast skies and the PEX collector was inoperable during this period. Without the sun to power the collector or provide passive heating to the thermomass heat storage test tank the temperature dropped for a daily low on November 10th of 73.9 F to 62.6 F by November 13th. The control test tank dropped from 62.6 F to 60.2 F over the same period. With nighttime outside air temperatures at -2.9 F the greenhouse temperature at the ground level dropped from 54.7 F to 39.7 F.
While the PEX solar collector that was under observation collected more than one million BTU’s during the two full months of Collector Test Alpha, even with the help of a second PEX collector, this was not enough additional energy to protect the greenhouse from freezing should the nighttime temperatures drop below -15 F if combined with continuous gray, overcast skies for two days or longer.


Compost heated aquaculture greenhouse Vermont

4seasongreenhouseVidéos:

  • Chauffage au compost dans les collines du Vermont – youtube
  • Projet Jean Pain, chauffe-eau composte – youtube
  • Serre 4 saisons Massechusets – youtube

Greenhouse Resources

by MotherEarthsNews

General Season-Extension Information

  1. Winter Gardening Tips: Best Winter Crops and Cold-Hardy Varieties
  2. Garden Know-How: Extend Your Growing Season
  3. 14 Ways to Extend Your Gardening Season
  4. Extending the Season

Cloches

  1. Undercover Device: The Cloche
  2. How to Make Mini-Greenhouses

Cold Frames

  1. Use Cold Frames to Grow More Food
  2. Cold Frame Gardening Success
  3. Build a Cold Frame for All Seasons
  4. How to Make an Inexpensive Cold Frame
  5. Build a Ventilated Cold Frame for Winter Vegetables
  6. Building a Cold Frame
  7. How to Build a Cold Frame and Hotbed

Hoop Houses

  1. Build This Easy Hoop House to Grow More Food
  2. Low-Cost, Versatile Hoop Houses

Low Tunnels

  1. Make an Easy, Inexpensive Mini-Greenhouse With Low Tunnels
  2. Try Quick Hoops — Easy-to-Make Mini-Greenhouses
  3. Use Low Tunnels to Grow Veggies in Winter: Quick Hoops

Greenhouses

  1. How to Choose the Best Greenhouse Kit
  2. DIY, Low-Cost and Multipurpose Greenhouses
  3. The Amazing, Low-Cost, Multipurpose, Solar-Heated Greenhouse/Guesthouse
  4. A Small Greenhouse From a Bus Stop Shelter
  5. Build a Greenhouse From Used Windows or Storm Doors
  6. Earth-Sheltered Greenhouse
  7. Choosing a Greenhouse
  8. Will’s Mini-Greenhouse
  9. MOTHER’s Portable Garden Room
  10. Designing and Building a Recycled Greenhouse
  11. How to Build a Window Greenhouse
  12. You Can Build Your Own Add-On Greenhouse
  13. Cut on a Hot Tin Roof
  14. How to Build a Low-Cost Greenhouse With Pine Poles
  15. Greenhouse Growing: Tips for Basic Greenhouse Cultivation
  16. MOTHER’s Backyard Greenhouse
  17. Build a Solar Window Greenhouse
  18. How to Greenhouse Garden
  19. Build an Ecosystem: The Earth-Sheltered Solar Greenhouse
  20. How to Build a Pit Greenhouse

Season-Extension Tips

  1. Real-World Winter Gardening Tips From Your Growing Zone
  2. Use Hog Panels for a Greenhouse Frame
  3. Raise Seedlings With a Greenhouse on Wheels
  4. Inexpensive Mini-Greenhouse
  5. Lightweight Plant Protector
  6. A Frost-Free Garden Greenhouse
  7. Simple, Heated Cold Frame
  8. Freezer Cold Frame
  9. Build a Free-Standing Greenhouse