[Market-farming] High Tunnel Winter Growing

DFORD8N at aol.com DFORD8N at aol.com
Mon Nov 23 17:54:10 EST 2009

Do you seed in the high tunnels during the winter, or do you transplant  
from plugs? I've been transplanting but I'd sure like to direct seed --  
especially stuff like spinach -- if I could get away with it, but I'm thinking  
that the soil is too cold for germination, no matter what you do to try to 
warm  it up. If you can get it up around 60 or 65 during the day, you're still 
going  to lose a lot of that at night, aren't you?
--Dave in West Virginia

In a message dated 11/23/2009 2:33:15 P.M. Eastern Standard Time,  
hattie_allen at yahoo.com writes:

I'm growing in a hightunnel with only one layer of plastic.   I'm in Zone 7 
and like the Wiedigers, I grow all winter easily.   Eliot Coleman is in 
Maine and that ain't too warm! He may be Zone 5 at  the warmest.  For Zone 3-4 
growing, I'd just stick with hardy  things, but you will still experience 
very warm temperatures inside the  high tunnel during sunny days.
yes, the growth slows way down, but I also found that if I allow  the high 
tunnel to heat up pretty well....to around 80 or 85 during as  much of the 
day as possible and cover more tender things like lettuce  with row cover and 
hoops inside the high tunnel--just during the very  worst of the winter 
here--that I DO experience growth because the ground  stays warm enough for 
plenty of activity.  Not a lot of growth, but  close to 1/3 of what I'd get 
outside of the 10 hours or less of  sunlight.  Ten hours and less...you'll get 
little growth, but  you'll get some and especially if you let it warm up.  I 
ALWAYS  vent the house, no matter what, but I vent it much less than I used 
to  when the days are cold, dry and sunny as I want to capture as much heat 
 as I can.
The killer days are the overcast, wet days.  You have to vent  because of 
the humidity and there is no sun to help warm things up and  that is a drag 
with absolutely no heat in the house.  
In my Zone 7, I'll be growing carrots, spinach, mustard greens,  turnips, 
parsley, dill, cilantro, scallions, starting leek plants,  arugula, pak choi, 
hardy lettuce varieties under more cover, etc.   I'm very late getting my 
high tunnel planted this year and still  harvesting lots from outside under 
rowcover.  But my high tunnel  will bring me very early harvests as the day 
lengthens...By February the  growth rate will increase a lot.
Coleman has done the work and the calculations.  If you read  his books, or 
at least get most of them for references, one or the other  will have the 
info that you need, including how to translate it to your  particular 
Oh one other really important tip from the Weidigers.  DO NOT  use raised 
beds in the high tunnel.  Keep them flat and they will  stay warmer.  Cold 
air sinks and it will sweep right across those  beds that are raised--and your 
soil will cool down, but if you  snuggle the rows down into the ground at 
the surface, they will stay  warmer.  It works.  They tested it and so have I.
It is my theory that the soil warmth is what makes all the  difference for 
growing in the winter.  Warm soil and a layer of  agribon on hoops over the 
soil will keep many things from freezing in  the most frigid of weather.  
The agribon will develop a film of ice  from condensation and this will serve 
as insulation for the vegetables  in the warm soil below.  And it is not 
necessary to use heavy row  cover.  In fact, that can be counterproductive.  
The heavier  cover traps the cold air and those beds take longer to warm up 
during  the day after a cold night....at least that is my experience.   I no 
longer use the heavy stuff at all.
Take the row cover off on nice days if you can.  Helps to  ventilate and 
just to give everything more light.

Hattie's Garden
31341 Kendale Rd.
Lewes, DE  19958

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