Transcript High Tunnel Selection and Construction

High Tunnel Fruit and
Vegetable Production
LESSON THREE: HIGH TUNNEL
SELECTION AND CONSTRUCTION
Interest Approach
 Different growing situations may require different
types of high tunnels.
 Why do each of these growers have different
needs?
 Scenario
1: Mr. Turner enjoys growing mostly
tomatoes.
 Scenario 2: Mrs. Mills lives in a high snowfall area.
 Scenario 3: Mr. Leonard grows in multiple high
tunnels spread out over a large area of land.
Objectives
 Discuss several issues that should be considered
prior to high tunnel construction.
 Recognize the different sizes and types of high
tunnels used in crop production.
 Identify the major components of a high tunnel and
their functions.
 Outline the high tunnel construction process.
High Tunnel Construction: Issues to Consider
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Location
Budget
Potential crops
Expansion
Market area
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Orientation
Airflow
Access
Irrigation
Drainage
High Tunnel Construction: Issues to Consider
 Shade
 Greatly
reduces the effectiveness of a high tunnel
since it limits light.
 Space
 Allow
two times the height of an obstacle away from
the high tunnel
 Example: A 25 ft. tree should be how far away from
the high tunnel?
 Answer:
50 ft.
High Tunnel Construction: Issues to Consider
 Multiple tunnels:
 East-west
orientation: spacing among the tunnels
needs to be twice the height of the tunnels.
 North-south orientation: spacing can be 4 feet among
them.
High Tunnel Sizes and Types
 Manufactured versus Homemade
 The
most important factor to consider is your budget.
 Homemade are usually less expensive and often less
permanent than commercially manufactured
structures.
 Be sure to choose structures that are made of
materials with the lowest environmental impact.
High Tunnel Sizes
 A typical tunnel is 15 to 30 feet wide and 60 to 96
feet long. Wide tunnels have the advantage of
being easier to manage. In most cases, tunnel
width should not exceed 30 feet.
 Tunnels exceeding 96 feet in length pose some
potential problems.
 Ventilation
 Temperature
variability
Two Main Types of High Tunnels
 Single-bay high tunnels:
 free
standing, or not connected to another high
tunnel.
 Multi-bay high tunnels:
 two
or more tunnels connected along the sides. Also
referred to as gutter connected.
Shape
 The shape of the high tunnel will affect the
performance.
 Single-bay high tunnels come in two primary
shapes:
 Quonset
(Hoop)
 Gothic Arch
Quonset
Quonset
 Lower cost
 Unheated Quonset structures can also serve as cold
frames for overwintering nursery stock.
 Multi-bay Quonset high tunnels cover large areas
and, per bay, are relatively inexpensive.
Gothic Arch
Gothic Arch
 Readily sheds snow
 15
% greater load-carrying capacity than a Quonset
 Taller sidewalls
 more
usable space along the sides for working
comfort, crop production and growth, and equipment
access.
 Height
 Great
for trellised crops such as tomoatoes
 Better ventilation
Major Components of High Tunnels
A. Rib, Hoop, Arch, Bow
B. Purlin, Ridgepole
C. End Wall
D. Hip Board
E. Side Wall
F. Baseboard
High Tunnel Construction Process
 Build and secure the frame
 Cover the frame
 It
is best to choose a calm, warm day and let the
plastic warm up so it will be easier to handle and
stretch more than if it is cold.
 End walls
 Zippered
ends or a large door must be constructed
in the end walls to permit ventilation in the summer
as well as entrance and exit of equipment.
Sides: Roll Up versus Roll Down
 High tunnel sides may roll up or roll down to open.
 Roll
down sides provide protection to plants when
only rolled partially down, which can prevent
abrasions to the plants. The abrasions then allow
entry for diseases and pests.
Manual versus Automatic
 Manual: Opened with a screw level
 Lower
cost
 Higher labor
 Automatic: Motorized
 Higher
cost
 Lower labor
 Motorized sidewalls are activated by a thermostat
inside the high tunnel and the vents open and close
automatically within preset temperature ranges.
Be Aware!
 The advantage of motorized sidewalls is that
someone does not need to be present for the
system to work.
 If the system fails to work, heat could build up
inside the tunnel and possible plant or crop loss
could result.
 If an automated system is present, then a buzzer or
phone alarm hooked up to a thermostat inside the
high tunnel might prevent a catastrophe.
Tools for Construction
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Level
Transit & Rod
String
Tape Measure
Sledge Hammer
Standard Hammer
Staple Gun & Staples
Shovels
Wrenches—5/8; 9/16;
½; 7/16; 3/8
 Cordless Drill & Bits
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(several)
Center Punch
Tin Snips
Skid Steer or Tractor with
Loader
Hay Frame Wagon
Additional materials
required: 2 x 6
Baseboards –Western
cedar or treated wood =
to length of tunnel and
framing materials for end
walls.
Scenarios
 Let’s look back at those scenarios and see which
type of high tunnel is most appropriate.
 Scenario 1: Mr. Turner enjoys growing mostly
tomatoes.
 Answer:
Quonset (trellised)
 Scenario 2: Mrs. Mills lives in a high snowfall area.
 Answer:
Gothic (snow falls off more easily)
 Scenario 3: Mr. Leonard grows in multiple high
tunnels spread out over a large area of land.
 Answer:
Quonset (less expensive and simpler
construction when installing multiple high tunnels)
Review
 There are several issues that should be considered
prior to high tunnel construction.
 Different sizes and types of high tunnels used in
crop production are available.
 High tunnels can be prefabricated or homemade,
each have their own advantages.