Season Extenders used in Vegetable Production

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Season Extendersused in Vegetable Production

• By
• Robert Tomesh
• UW Extension

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One can extend the vegetable growing season by
sheltering plants from cold weather and by
capturing solar heat in both the air and soil,
both in early spring and during the fall.
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Season Extending Methods

• Cold frames
• Hot beds
• Cloches
• Hotcaps
• Plastic soil mulches
• (Shading)

• Tunnels
• Row covers
• Greenhouses

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Cold frames (sun boxes)

• Rely on the sun for their source of heat
• Have no outside energy requirements
• Relatively inexpensive structures
• Used for cool season crops during spring and fall

Cold Frame
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Ideal Locations for Cold Frame

• South or southeastern exposure
• 10 slope facing exposure
• Sheltered location to protect from winds
• Inset into ground for insulation or insulated
• Painted black inside to capture solar energy

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Warm Weather Cold Frame Care

• On warm sunny days, it will be necessary to open
  the sash
• Cover the sash with a shade cloth to provide a
  cooler environment
• Treat sash glass with a lime wash

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Plant Care in a Cold Frame

• Prepare soil to a depth of 12 to 18 inches
• Water daily or as needed
• Fertilize about every three weeks using a soluble
  fertilizer
• Pest management slugs, soil diseases if soil is
  too wet and leaf diseases when plants are crowded

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Portable Cold Frame

• Container or plastic tote which can be set
  outside during warm weather and brought in during
  cold periods
• Easily managed

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Dutch Light (Cold Frame)

• Cold frame which is a lightweight and is portable
  and moved around the garden

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Hot bed

• Cold frame with an added heat source
• Sash to capture solar heat
• Strawy manure buried beneath the root zone
• Steam carrying pipes
• Electric heating cables
• Light bulb

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Growing Vegetables in an Hot Bed

• Start crops earlier in the season
• When enough heat (55 degrees F.) is added, warm
  season crops can be grown
• Soil heating cables used for seed germination

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Cloche (pronounced klosh)

• Cloches are set out over individual plants or
  made into tunnels
• Protect plants from cold air and drying winds
• Trap solar energy and soil moisture (Hot caps)

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Examples of Cloches

• Bell glass jars
• Boards for wind and shade protection
• Milk jugs
• Wall-of-water

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Hot Caps (Cloches)

• Capture solar energy to warm air inside
• One gallon milk jugs
• Waxed paper hotcaps
• Wall-of-water, water filled plastic tubes
• Plastic tubes had highest internal air and
  retained heat the longest at night

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Plastic Soil Mulches

• Clear plastic
• Black plastic
• Colored plastic
• All increase soil temperature and hold heat
  during night periods
• Black 5 10 degrees
• Clear 10 20 degrees

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Shading

• Used to start seeds and young plants for fall
  crops (July and August)
• Build portable shade frame
• Shade house, shade cloth over trellis, or lath
  strips

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Floating Row Covers

• Clear plastic

• Spunbonded polyesters

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Clear Plastic Covers

• Used to warm soil prior to planting
• Increase soil temperature 10 to 20 degrees F.
• Temperatures above 85 degrees F. can damage plants

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Spunbonded polyesters

• Provide 4 5 degrees of frost protection to 28
  degrees F.
• Opened when internal air temperatures reach 85
  degrees
• Problem with low light transmission of 75 to 80
• Weed Growth

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Floating Row Covers

• Row covers mean earlier harvests
• Used for leafy vegetables
• Root Crops
• Starting fruiting crops
• Greater yields
• Extended fall harvests

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Floating Row Cover
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Supported Row Covers

• Also Called Low Tunnels
• Can use PVC pipe, heavy wire
• More labor needed
• Support needed for crops such as tomato, pepper
  and summer squash
• Weed control needed between rows

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Low Tunnels
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Low Tunnels

• Miniature greenhouse with reduced air volume
• Often one or two layer (insulating value) of
  plastic
• Used for cool season leafy crops lettuce,
  spinach, endive

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Zip Houses

• Mini greenhouse
• Ability to easier regulate temperature, light and
  ventilation
• Frost protection down to 26
• Open and close easily from end of row
• Reusable for 2-3 seasons

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Zip Houses

• Protects from heavy rains, heavy winds and small
  hail
• 20-30 wide and 21-25 tall
• Cut to any length strings stay ready to pull
• 500 roll 158 SH

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Hoop Houses

• High tunnel
• Many manufacturers
• Build your own
• Anchored in ground
• Many heights/lengths
• Some large enough for tractors
• Sides and ends for ventilation

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Trial Hoop House Design
Dan Mielke tomatoes, peppers and cukes
Penn State Research Facility
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Hoop Houses

• Selling fresh local tomatoes in June
• Give you months of extra hours in a growing
  season
• Cultivating spinach and leafy greens year round

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High Tunnel Houses
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Simple Hoophouse

• Simple to Build
• Frame of plastic or metal pipe
• Anchored by ground posts
• Open ends
• Ventilation important
• Doors, sidewalls other vents

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Classic A-Frame

• Very easy construction
• Steep roof sheds snow
• Limited space (no room for benches)
• Growing space for tall plants
• Ventilation important
• Can have second layer of plastic on inside

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Gothic Arch

• Can be portable or anchored to foundation
• Curved walls shed snow
• Inexpensive
• Lets in lots of light

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Benefits

• Extending cropping season
• August/September seeding spinach, broccoli,
  other greens
• Harvest until December
• Limited by sunlight w/out supplemental light
• Mulch with straw and harvest root crops
  throughout winter

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One Growers Experience

• 20 x 96 foot tunnel
• 4 rows tomatoes
• 2 rows of peppers
• 1 row of cucumbers
• Yields
• 4,500 lbs of tomatoes
• 13 bu of peppers
• 300 lbs of cucumber

• Cost of tunnel - 2000
• Sales 5000

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Solar Greenhouses

• Basic principles of solar greenhouse
• Solar Design
• Solar Heat Absorption
• Solar Heat Storage
• Insulation
• Ventilation

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Sun - Pit

• Foundation sunk below ground with concrete block
  walls
• More expensive initially
• Recoup costs from heating savings
• Need good drainage
• Accessibility concerns
• Higher initial costs

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Attached Lean-To

• Strong, easy to construct
• Energy savings
• Can attach to house wall with existing door
• Need good ventilation

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Attached Solar

• Connected to house with sliding glass doors
• Helps heating house in winter
• Summer Cooling from House
• Rigid acrylic or polyethylene panels

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Guides to Solar Heating

• Solar orientation
• Heat absorption materials
• heat exchange through phase-change or latent
  heat storage materials
• Basic information secured from books and articles
  that focus on solar greenhouses

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Freestanding - Shed Type Greenhouses

• Steep north roof pitched to the highest summer
  sun angle for maximum year-round light reflection
  on to plants
• Vertical north wall for stacking heat storage
• 40-60 degree sloped south roof glazing
• Vertical kneewall high enough to accommodate
  panting beds and snow sliding off roof
• End walls partially glazed for added light

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Design and Orientation Freestanding Greenhouses
Cold winters, northern latitudes
Cold winters, middle U.S. latitudes
Mild winters, southern latitudes
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Suns Path Summer/Winter
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Solar Heated Greenhouse
Reflective material on wall
Thermal curtains
South wall -glazing
North wall
Can insulate north wall with straw before placing
collectors
Collects reflective solar heat
Heat collection system
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Solar Heated Greenhouse
Reflective material on wall
Thermal curtains
South wall -glazing
North wall
Can insulate north wall with straw before placing
collectors
Heat collection system
Winter orbit south
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Insulation

• Walls and Doors
• seal doors and vents with weather stripping
• Polyurethane foams, polystyrene foams, and
  fiberglass batts are good
• need to be covered so they stay dry
• Floors
• floors are one place overlooked in insulating
• dig out soil place foam board then soil over
  boards
• will need to replace board often

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Growing Smart

• Be innovative
• Be COST effective for net gain
• Use some of each systems described
• Experiment to see what will work for how many
  months
• Use list of books at back of handout for more
  information