Re: veggie-digest Digest V102 #11

Subject:  Re: Anyone there?
   Date:  Sun, 21 Apr 2002 22:12:59 -0500
   From:  James <is23@bellsouth.net>
Well,here in Southern Mississippi, its beautiful!!!!  Finishing up fall
gardens,of collards,turnips(white egg,purple tops)mustard(Fla.broadleaf)brussel
sprouts,radishes,rutabeggars,brocolli.Irish potatoes went in Feb.,along with new

crops of turnips,mustard.Feb.,brought Field corn,sweet corn,several snap
beans,field peas,squash,tomatoes.April brought
watermellons,cantalope,okra,cucumber,peanuts,etc.I built me a small
greenhouse,and went to school,the hard way,and done fair.I experenced things,the

books don't tell you,about small houses.Small greenhouses are GREAT PROBLEMS,---

temperatures up and down bad,and in my area,cooling is more important than
heating.I also had war with damping off,but whipped it,through books,and
thinking.
=========================

Hi Jim, from Ed in Rockford, Illinois (almost to Wisconsin)--

Reading your comments, I'm jealous.  Right now it's 36° and overcast.  Last week

had a couple very unusual 80° days.  I target May 1st for planting.

I am seriously planning a greenhouse.  Specifically a "hoop house", and I wonder
if
I can learn from anyone experiences?  Here is what I am reading, but nothing
definate---



     High Tunnels for Early Spring/Late Fall Production of Tomatoes & Other
Crops
       - Michael D. Orzolek, Professor of Vegetable Crops  -- October 7, 1999
       - Otho S. Wells, University Of New Hampshire

       Plant growers worldwide strive to control the environment in which plants
grow. Temperature is generally the predominant concern, followed by humidity,
light, water, nutrients, and pests. Methods range from an inexpensive plastic
milk jug placed over a tomato transplant in a home garden to the ultra-modern
greenhouse controlled by sophisticated computer technology. The vast majority of
vegetable growers in the United States, utilize systems that fall somewhere
between these two extremes. Hot caps, plastic mulches, and row covers (low
plastic tunnels and floating covers) are internal environmental control. And
more recently, high tunnels have begun to take on an extra
use of the production of tomatoes and other crops.

       From the outset, it should be noted that high tunnels are not something
"hot off the press." For many years they have been used extensively in Europe,
Asia, and the mid-East for early production of vegetables, fruit, and flowers.
And to some extent, here in the United States, they have been used as
overwintering structures (hoop houses) for ornamentals. For all practical
purposes, however, very few high tunnels are used in this country for the
production of vegetables. I believe we will see a dramatic increase in the next
few years.

      What is a High Tunnel? -- A high tunnel is not a greenhouse, except in
concept. A high tunnel is a quonset-shaped, plastic-covered greenhouse-like
structure which has neither an electric- powered ventilation system nor a
permanent heating system.
      The only external connection is water. Solar heat and natural ventilation
are utilized for temperature and humidity control. In contrast to a greenhouse
which hasdouble layer of plastic (or glass), a  permanent heating and
ventilation system, and other amenities like thermostats, lights, and multiple
electrical outlets, a high tunnel is "sparsely" outfitted.
It is like a protective shell sitting in a field providing season extension in
the spring and fall.

      The Structure -- A high tunnel is not complicated, yet from the experience
of many growers in New England, they have found it easier to purchase a unit
than to bother with do-it-yourself construction, unless several units are to be
erected. The basic system includes a metal frame covered with plastic, a trickle
irrigation system, and a piece of black plastic on the ground,  and roll-up
sides.

      Size. Length is not critical, but width is. The width should not exceed
the capacity for natural ventilation. A reasonable width seems to be 14 to 20
feet; however, if a tunnel is located on a site where the "wind comes sweeping
through," a greater width is feasible. In New England, a standard size is 14 x
96 feet. Size is partially dictated by the availability of various sizes of
plastic.

      The Frame. Framing materials include wood, PVC, and galvanized metal, the
latter being the most popular and the most durable. Metal bows (one- or
two-piece) are attached to metal posts which are driven into the ground 18 to 24
inches deep and extend out of the ground at least 2 feet. Baseboards are
attached to the posts. About 3.5 feet above the baseboard, a hipboard (for
example, 1 x 4 board) is attached to each of the bows. The plastic covering is
attached to the hipboard by fastening a batten strap (with screws or nails) to
the hipboard with the plastic sandwiched between. End walls (wood framed) may be
either permanent or portable, the latter allowing removal to accommodate a
small        tractor with a rotary tiller or other attachments.

       The Plastic Cover. The tunnel is covered with single layer of 6-mil
greenhouse grade polyethylene which will last
3 to 4 years. Construction grade plastic will also work well for one season--
and in an area not subject to high winds.
The cover should be taut when applied. It is fastened to the hipboard with the
batten strips. To keep the plastic firmly
in place, the batten strip should be secured about every 18 inches with deck
screws and washers.

      Ventilation. Natural ventilation is accomplished with the use of roll-up
sides Q from the baseboard to the hipboard. Depending on the temperature, wind
direction, and wind speed, each side is rolled up to the height necessary for
temperature and humidity control. The two sides may be opened at different
heights. A simple roll-up method is to tape the edge of the plastic cover to a
one-inch pipe running the length of the tunnel, and attach a sliding "T" handle
to one end of the pipe (see diagram).

      Trickle Irrigation. Trickle irrigation is essential for adequate and
timely watering and/or feeding. One line per row
(or per double row) is sufficient. The trickle lines are laid out and anchored
before the ground cover is applied.

       Ground Cover (Mulch). For best results with most crops, the total soil
surface is covered with a single sheet of 6 mil black plastic. This serves to
warm the soil, control weeds, reduce soil moisture evaporation, and to serve as
a  barrier against diseases that might be in the soil. Be sure that the cover is
well secured along the edges to prevent wind from billowing up the plastic over
young plants.

      Location of the Tunnel. A high tunnel should be located on good soil that
is well fortified nutritionally and that is well drained. Full sun is important,
even though high temperatures will  have to be managed. To aid in natural
ventilation, orient the tunnel so that  prevailing breezes will blow through the
tunnel from side to side.

      Temperature Management. Excessively high temperatures can be very
detrimental to tomatoes when they are in blossom. Attempt to keep the inside
temperature below 90 degrees F, which might be difficult on some days. Roll the
sides up the first thing each morning to control temperature and to flush out
the humidity. In early evening, roll down the sides to entrap as much heat as
possible; and continue to roll down the sides each evening until night
temperature (outside) is up to  65 degrees F. High tunnels are not greenhouses;
therefore, the expectations from a  high tunnel are not the same as from a
greenhouse. Low temperatures can be serious threat to early planted crops inside
a tunnel. Consequently, do not plant more than about 2 to 3 weeks earlier in a
tunnel than outdoors. Otherwise, supplemental heat might be required. Even so, a
standby propane unit is advisable just in case.

      Other Management Practices
       Water. Ample water is needed for the general growth of the plants and to
prevent blossom-end rot in tomatoes. Because the black plastic covers the soil,
it is not easy to inspect soil moisture. Pull back the plastic and take a close
look at the soil as if it were a field soil. The soil should be kept moist, but
not soggy wet.
       Pests. Diseases have not been a serious problem, except an occasional
problem with botrytis or gray mold when humidity was too high. To control early
blight, do not plant field tomatoes close to the tunnel. Whiteflies can become a
real nuisance if not checked early on. Do not allow them to build up. Soap
insecticides are effective for small populations of white flies.
      Growing System. In a 14-foot wide tunnel, we have found that 4 rows of
tomatoes grown with the basketweave trellis is the most efficient way to manage
the plants. The rows are 3.5 feet apart and the plants are 18 inches apart in
the row. Either determinate or indeterminate varieties may be used since they
are topped out at about 3 to 4 feet high.The economics of high tunnel crops will
vary; however, with tomatoes, high tunnels provide about a month of earliness,
which coupled with good retail prices, the tunnel pays for itself the first
year. See the attached sheet on economics.

      Summary
      High tunnels are a protected growing system that will provide about one
month of earliness in the spring. They are not high cost structures, thus
allowing for low-capital entry into crop production. Generally, high tunnels are
part of a diversified operation, contributing to the early phase of overall
production and marketing. While production in high tunnels continues throughout
the season, it is the early market that is most important.
      _____________________________________________________________________
      Economic Feasibility of High Tunnel Tomato Production
      (one tunnel @ 14' x 96' = 1,344 sq. ft.)
      _____________________________________________________________________
      I. Structure Costs
      A. Frame Boards (PVC posts & Bows)                 $200.00
      B. Side Boards
      1" x 6" x 96' x 2 @ $.50/LF                            96.00
      1" x 4" x 96' x 2 @ $.18/LF                            34.56
      C. Pipe & T Handles (roll-up)                         37.50
      D. End Walls 2" x 4" x 47' x 2 @ $.24/LF       22.56
      E. Construction Labor, 32 hrs. @ $8.00/hr    256.00
                                                                         $546.62

      II.Plastic & Trickle Irrigation
      A. Cover, 1 layer 703, 6 mil 24' x 100'        $203.79
      B. Black poly sheeting, 6 mil 16' x 100'           63.10
      C. Trickle Irrigation                                         85.00
                                                                         $351.89

      III."Annual" Expenses and Returns     Per Tunnel     Per Pound
       Receipts 2,000 Pounds @ $1.60/lb.    $3,200.00          $1.60
       Marketing Costs  (25% of receipts)        $800.00          $0.40
       Production Expenses
       A. Plants, 7 sq ft./plant, 192 plts. @ $.15            $28.80
       B. Stakes, 192 @ $.25 each                                 48.00
       C. String, 2500 ft.                                                 15.00

       D. Fertilizer-Starter, 10-20-20 & Lime                   5.00
       E. Fertilizer through Trickle Irrigation                     20.00
       F. Containers, 100 20 lb. boxes @ $1.10 each   110.00
       G. Labor @ $8.00 hr.
       Till, spread fert. & plant, 3 hrs.                             24.00
       String plants, 3 hrs.                                               24.00

       Prune, 2.5 hrs.
20.00
       Harvest, 8 har. x 4 hrs.                                       256.00
       Annual Maintenance, 10 hrs.                                 80.00
       H. Misc. (small tools, repairs, rototill)                    25.59
       I. Operating interest @ 5 percent $656                 32.79
       Subtotal variable expense (Sum A-H)               $688.59
       J. Annual capital recovery & interest
       Structure ($1346.52, 10 yrs., 11%)                   228.66
      Plastic & irrig. (351.89, 5 yrs., 11%)                    59.75
      Subtotal fixed costs (J&K)                               $288.41

     Variable and fixed production costs                             $977.00
$0.49
     Net returns (receipts- marketing, production costs)   $1,423.00   $0.70

+----------------------------------------------------------------------------+
     Michael Orzolek, Coordinator   --  Document Number: 2940170
     Department of Horticulture, Penn State --  (814) 863-2251
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