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  • From: "Kathy Somers" <somersfarm AT kingcon.com>
  • To: "'Market Farming'" <market-farming AT lists.ibiblio.org>
  • Subject: Re: [Market-farming] straw bales as greenhouse heat source??
  • Date: Wed, 18 Jan 2006 06:49:49 -0500

Hi,
I have been reading the discussion in regards to how early can you plant
tomatoes in an unheated high tunnel. We live in zone 3 in Northern Vermont.
Two years ago, before we built our second heated greenhouse, we put tomato
plants in our unheated high tunnel the first week of May. In Vermont our
last frost fee date is close to June 10-20th. We had a real cold spell. I
put wire hoops over the plants and put two layers of the heavier row cover
over them. The next morning I went up to the high tunnel. I had a
thermometer under the row cover sitting on the black plastic and one outside
the row cover. The temperature outside was 19 degrees. The temp in the
high tunnel was 25 degrees and the temp under the row cover was 39. I do
recall the day before this freeze was sunny, which helped heat things up and
the row covers went over the tomatoes in the afternoon and were able to trap
some heat as we closed up the high tunnel doors early that day. The tomato
plants at either end of the tunnel didn't fare as well, as there was more
stress from the cold on the ends.

I am not sure I would plant that early again in an unheated environment. It
puts a huge stress on the plants especially tomatoes to get that cold. All
of the other veggies fared well with row covers, but they were more
adaptable to the cold. I guess having some source of emergency heat would
be a comfort.

Kathy in Vermont


-----Original Message-----
From: market-farming-bounces AT lists.ibiblio.org
[mailto:market-farming-bounces AT lists.ibiblio.org] On Behalf Of Steve Diver
Sent: Tuesday, January 17, 2006 6:30 PM
To: market-farming AT lists.ibiblio.org
Subject: [Market-farming] straw bales as greenhouse heat source??

Hey Allan -

The main concept is how many *weeks* can you
transplant tomatoes into high tunnels before the
last frost-free date in springtime..... but read onwards.

The Penn State high tunnels project can
provide planting dates for the WV region.

http://plasticulture.cas.psu.edu/H-tunnels.html

Of course there are hoop house growers in
the crowd who can explain how they do it,
like Paul and Alison Wiediger with Au Naturel
Farm in Kentucky.

http://www.aunaturelfarm.homestead.com

On the other hand, a fascinating result of high tunnel
research and practice is that people are finding out that
tomatoes perform very well under protected shelter
in the *summertime*.

These could be hoop houses with the sides
rolled up, Hay Grove tunnels, and so forth.

The differences in plant health and therefore plant
productivity later into the growing season between
protected shelter and open field tomato production
are *dramatic*.

It largely has to do with rain protection and
dry climate growing conditions, and therefore
disease protection.... especially so in the
Humid East regions of the United States.

There are several ways to reduce risk from frost and
improve the heat-warming growing conditons of a high
tunnel if warm-season nightshades and cucurbits are
your goal for high tunnel production.

The first is the use of plastic mulch and hooped
row covers "inside" the hoop house, or to add a
second layer of poly coupled with a squirrel-cage
fan to provide an insulating layer.

The second and most *sensational* improvement --
essentially upgrading from a hoop house to a heated
greenhouse -- is the integration of root-zone heating
fueled by an on-demand water heater.

You can have an air temperature of 36-46 degrees
inside the high tunnel at chest height and still
grow fantastic crops, as long as your root temperatures
are "warm".

http://www.attra.ncat.org/attra-pub/rootzone.html

Fyi, two additional sources of excellent information for
high tunnel production are the K-State/Univ of Missouri
project and the Noble Foundation in Oklahoma.

http://www.hightunnels.org

http://www.noble.org/Ag/Research/Horticulture.htm

Best wishes,

Steve Diver





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