Outdoor Winter Veggies in Mid-January

This is proof that winter vegetables can tolerate very cold temperatures.  We're in Zone 7 and although we've had an unusually mild winter, we've had cold nights.  Last night was mid-20's and tonight it'll dip down into the upper 10's.  Sara, my neighbor, planted her greens and herbs from Sow True seed last Fall and we've all been enjoying them since.  She has them in the backyard in a sunny spot and has recently began covering them overnight.  Thanks, Sara!!

Temperature Control for Winter Cool Crops

    When asked what greenhouse owners plant over the winter months, the more common responses are that some grow a variety of summer veggies which require high heating and lighting but honestly, who wouldn’t eat ripe tomatoes and cucumbers all year round?  Some don’t grow anything at all due to high fuel and energy costs but interestingly enough, there is a growing group of vegetable growers, private and commercial, that prefer to grow “cool crops.”  For temperature controlled environments such as greenhouses, these cold resilient vegetables are ideal for winter growing not only because they thrive at cold temperatures but also because of the minimal amount of heat energy needed to successfully grow them. Less energy required equals less costs to warm a space that inherently dissipates heat.
    All root vegetables (kohlrabi, turnips, beets, carrots, radishes, potatoes), hardy greens (kale, chard, spinach, mustard greens), anything in the cabbage family (cauliflower, broccoli, brussel sprouts), onions, and various herbs (parsley, cilantro) prefer cold temperatures.  They can grow outdoors in places where average low temperatures are around freezing but they flourish in greenhouses that maintain temperatures right above freezing.  
   Setting your thermostat inside your greenhouse at 35 degrees Fahrenheit will create an efficient temperature to grow cool vegetables as well as keeping your water supply from freezing.  Depending on the weather conditions of where you live and the construction of greenhouse you have, maintaining temperatures right above freezing, may easily be accomplished for the majority of places in the US through passive solar heating.  By simply storing heat from the daytime in some type of thermal mass inside the greenhouse, it can then be released at night when temperatures drop.
    Some different types of thermal mass greenhouse owners use are water, rocks, bricks, concrete, dirt, mulch, manure, straw bales and various types of phase change materials.  Some are better than others.  
   The performance of phase change materials are better solely because it stabilizes temperature while releasing its heat.  A good example is savENRG PCM at 32 degrees F.  This PCM is made from salt hydrates and is non-toxic and non-flammable.   It will consistently release a temperature of 32 degrees F and will require lesser quantities than other forms of thermal mass, providing more growing space inside the greenhouse.
   Regardless of what thermal mass is used and how you heat your growing spaces, keeping temperatures right above or around freezing during the cold season is reasonable and can be achieved with minimal energy costs.  At the same time, planting cool crops provides families and local communities with healthy and seasonal vegetables throughout the winter months.

Greenhouse at Asheville-Buncombe Technical Community College

South-side of greenhouse
-located at Sycamore Bldg., A-B Tech
-approximately 1200 sq. ft.
-construction with 1 ft. thick cement blocks and single layer glass
-heated with 2 steam unit heaters
-forced air ventilation on outside west wall, windows open and shut

Winter CSAs'

    Is there anything bad about being part of a CSA?  You receive a variety of super fresh, locally grown, vegetables and fruits, directly from the farm to the consumer.

   The only part that takes a little bit of thought, at least for me, is having to come up with new recipes for veggies and fruits that I don’t normally buy and eat.  But really, is adding variety and vitamins to our diets a negative thing?  How terrific would it be to have CSA’s all year round even in winter?  Winter Sun Farms is doing this through Blue Ridge Food Ventures and local farms.  Check them out at http://www.wintersunfarmsnc.com/

   A great way to to grow winter vegies in WNC is to grow indoors in greenhouses.  WNC winters can be harsh and we often experience snow, frigid winds and temperatures.  Greenhouses provide shelter, heat and a controlled environment.  So, why don’t all farmers do this?  I assume it’s due to the difficulty and cost of building and maintaining greenhouses with heating as its highest energy expense.

    RGEES, LLC is currently working on developing a procedure for heat storage solutions in greenhouses by maximizing the thermal mass and using latent heat storage through phase change materials.  What is thermal mass and latent heat storage?  It is anything that absorbs solar heat and energy during the day when the sun is out and then releases it at a later time.  Our main purpose is to design a practical and useful system that will dramatically reduce overall energy costs by decreasing fossil fuel consumption.

   We welcome any and all input from farmers, greenhouse owners/operators and experts on greenhouse heating and cooling.

--We’d like to know what your biggest challenge is concerning temperature?
--What kind of return on investment you expect (less than 5 years, 5-10 years)    

If you already have a greenhouse, we’d like to know about:  location in relation to seasonal temps, square footage of gh, structural layout, coverings, insulation materials, thermal mass, time/seasons of operation, desired gh temperatures for summer and winter months, heat/cooling systems, fossil fuel consumption, annual energy costs.

   Please feel free to contact me at nina@rgees.com

Heating at Huckleberry Ridge Farm's Greenhouse

     Recently, I’ve been visiting local farms and nurseries to check out the how the locals have constructed their greenhouses and the creative ways in which they are heating and cooling them.

    My first visit was to a lovely, little dwelling in Old Fort called Huckleberry Ridge Farm.  The owners, Ken and Judy, have built a small greenhouse that they use to grow greens during the winter months.  There is an infrared system that heats the dirt the on table beds where the greens grow.  They supplement with a wood stove and small fan to circulate the warm air on cold winter nights which has substantially, lowered their heating bills.  They’ve cleverly, placed bubble wrap on the inside of the roof covering for added insulation as well as insulating the backwall and using bagged leaves on the edges of the greenhouse.  They’re always seeking more efficient ways to heat the space and to increase temperatures during winter to grow more food.  A phase change material of 70 to 80 degrees F would be a perfect fit to store the heat for later use,  for decreasing fossil fuel consumption and burning less wood.   

    Judy and Ken’s specialty is fine rabbit meat.  They have beautiful, healthy rabbits which they process themselves at the farm, chickens for eggs, various greens and vegetables and lively ducks and geese that roam the property!  I can attest that their rabbit meat is delicious and they’ve got the best tasting eggs we’ve had thus far!

Thank you for the visit, Judy!  
Huckleberryridgefarm@hughes.net

Indoor Agriculture

 The importance of temperature control:

    The science and practice of producing high quality, high quantity plants and veggies indoors is better understood and precisely controlled more today, than ever in the past.  I’ve been reading quite a bit on controlled environment agriculture (CEA) or hydroponically-based agriculture.  Although it may seem unnatural to grow plants in a such a manipulated manner, there are irrefutable advantages to hydroponics.  

PCM Trees at Das Tropenhaus, Berlin

   This is by far the most creative usage of phase change material in a greenhouse application, I’ve ever seen.

   Just a quick bit of history... Construction of the botanical gardens in Berlin began in 1897 with the purpose of exhibiting exotic plants brought back from the German colonies.  ”Das Grosse Tropenhaus”, a main feature of the botanical gardens, is currently the largest, self supporting, glass structure in the world.  

   This gigantic tropical greenhouse maintains a temperature of 30 degrees Celsius with high humidity.  Before its recent renovation, it utilized approximately 1,500 tons of coal a year.  After recent renovation, energy consumption levels are one-fifth of previous usage.  Wallboards, tiles and concrete containing PCM, were considered for energy storage inside the structure.