Gardening Beyond the Frost; Gardening Guidebook for Davis County, Utah www.scribd.com/doc/239851313 ~ University of Utah, For more information, Please see Organic Edible Schoolyards & Gardening with Children www.scribd.com/doc/239851214 - Double Food Production from your School Garden with Organic Tech www.scribd.com/doc/239851079 - Free School Gardening Art Posters www.scribd.com/doc/239851159 - Increase Food Production with Companion Planting in your School Garden www.scribd.com/doc/239851159 - Healthy Foods Dramatically Improves Student Academic Success www.scribd.com/doc/239851348 - City Chickens for your Organic School Garden www.scribd.com/doc/239850440 - Huerto Ecológico, Tecnologías Sostenibles, Agricultura Organica www.scribd.com/doc/239850233 - Simple Square Foot Gardening for Schools, Teacher Guide www.scribd.com/doc/23985111 ~

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Gardening Beyond the Frost
Britney Hunter
Horticulture Extension Faculty
Davis County

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250,000 Tiny Greenhouses, Each
Containing One Head of Lettuce

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Overview
• Intro to high tunnel greenhouses
• Understanding weather
• Temperature management
• Growing calendar

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High Tunnels
Walk in, drive in
Don’t overheat as quickly as low tunnels
Space for mature plants
7’
14’
2’

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42’ x 14’ USU High Tunnel
72 plants per tunnel
~10lb per plant
= 720 lbs!

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Backyard Warm Season Tunnel
Winter Squash
Beans
Peppers
Tomatoes
Zucchini

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“Don’t try to create an endless
summer; instead, work with the
seasons.”Farm manger,
Barbara Fuller. La
Nay Ferme in
Provo

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Understanding the Weather
“Wind and frost (the true garden killers)…”

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Freeze Free Period (a.k.a Growing Season)
Utah Climate Center
http://climate.usurf.usu.edu/reports/freezeDates.php
Location Freeze Free Period (AVERAGE)
Logan (Cache) May 14 – Sept 26 (125 days)
Brigham City (Box Elder) May 4 – Oct 11 (159 days)
Kaysville (Davis) May 1 – Oct 13 (165 days)
Salt Lake Airport April 26 – Oct 18 (175 days)
Provo (Utah) May 1 – Oct 12 (165 days)
Moab (Grand) April 17 – Oct 17 (184 days)
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec

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Frost vs. Freeze
Definition of frost/freeze warnings issued by National Weather Service.
Warning Wind Speed Air temperature
Frost Below 10 MPH Above 32oF
Frost/freeze Below 10 MPH Below 32oF
Freeze Above 10 MPH Below 32oF

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Night Time Radiation Freeze
32°F

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GROWTH RESPONSE TO TEMPERATURE

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Temperature Responses
Cool Season Crops
Crop Min Opt Max
Onion 45 55-75 85
Cabbage 40 60-65 75
Salad 45 60-65 75
Potato 45 60-65 75
Perennial 45 60-65 80
Warm Season Crops
Crop Min Opt Max
Bean 50 60-70 80
Corn 55 65-75 90
Melon 55-60 70-80 90
Tomato 65 70-80 85
Sw Potato 65 70-85 95

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How does it work?
The original “greenhouse effect”

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Managing temperatures
High tunnel
Low tunnel
Floating
row
cover
Ventilation and shade
• How cold or heat can plants tolerate?

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Cultural and Environmental
• Microclimates
• Plastic mulch
• Raised beds

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Covers
Type Protection
*near freezing
Advantages Disadvantages Cost/10
tomato plants
Row cover cloth
(Reemay®)
2-4 °F Can leave on Can blow around,
not air tight
$15
Plastic 2-4 °F Air tight Needs support
Must ventilate
$18
Plastic + cloth 4-13 °F Better protection
custom size
Needs support
Must ventilate
$33
Wall o’ water 10-22 °F Can leave on Size, not air tight $33
Plastic/glass cloche 2-5 °F Air tight Size, must ventilate $80
Paper cloche
(HotKap)
2-4 °F Inexpensive flimsy, limits light $10
*Environmental factors prevent 100% accuracy

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Air Temperature with Soil Heating Cables

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Cold Frames
• Temperature Protection
• depends on materials (2-10°F near freezing)
• Advantages
• Sturdy
• Compatible with automatic opener
• Greens year round
• Disadvantages
• Not big enough for mature plants
• Overheat quickly

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Tunnels
• Temperature Lift
• 2-4 °F near freezing
• Added protection by stopping wind
(hard to measure)
• Advantages
• Tall enough to grow most plants
• Can be built for individual needs
• Disadvantages
• Must be ventilated
• Can get expensive

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Tunnel Design: Low Tunnels
• Heat up quickly
• Not tall/wide enough
for mature plants
Insect net

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Colorado State Extension
http://www.ext.colostate.edu/mg/gardennotes/722.html

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The Yearly Growing Calendar
- Mellow Management: Season Extension
- Small scale growers
- Backyard gardeners
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec
Cool Crops Cool CropsWarm Crops
Seed indoors warm Crops
Direct seed
Thanksgiving
cold crops
Transplant Thanksgiving
cold crops

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Time Line – Garden High Tunnel
Seed tomatoes Mar. 1
Plant tomatoes April 15
Seed lettuce Jan 15 - Feb 15
Plant lettuce Feb 15 - Mar 15
COOL SEASON WARM SEASON
Seed spinach Aug 1 - Sept 1
Plant spinach Sept 1 - Oct 1
COOL SEASON

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Idea for winter watering:
• Use a large water tank for watering in the cold
season
– If by chance it does freeze solid, it will likely be during a
time when you don’t need water

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27
First Harvest July 7, 2009
Outdoors: ~ August 10

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Warm Season Tunnel
Winter Squash
Beans
Peppers
Tomatoes
Zucchini

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Late July in Warm Season Tunnel
• “Lots of powdery mildew on
the winter squash and
zucchini”
• “Tomatoes and peppers are
doing well”
• “beans have yet to
blossom”
• “no fruits on the melon”

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Considerations for Success
• Drip irrigation
• Plant spacing
• Temperature requirements
• Fertilizer
• Pollination

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Summary:
• Covers and structures increases temperatures
during the day so plants start growing earlier,
and will fruit sooner.
• Ventilation and cooling is critical
• Covers and structures protect plants a little at
night, but plants can still freeze

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Selecting a Design
Type Ideal Situation Why to use Why not to use
Cloth Cover Few plants Easy Benefit is limited
Cold frame Fanatic about greens Easy Not big enough for tomatoes
Low tunnel Don’t mind ventilating Custom size If you forget, the party is over
High tunnel Farming/ small business $ Premium Ventilation and maintenance

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extension.usu.edu/publications
Illustrated web version

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Keys to Success
Soil amendment and aeration
Between crops
Seeding tool makes it easy and fun
Wire support increases efficacy and
keeps the cloth clean

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5 - 6’
SNOW
LOAD

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Cost/Economics
• 14’ x 42’
• $500 (materials)
• ‘FarmTek’
• 14’ x 24’
• $800 to $1000 (materials)

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USU Garden Tunnel
$260.00

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Other Resources

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Questions?
http://extension.usu.edu