2. What is season extension?
Increasing the growing season at
either end, spring and/or fall
3. Why try to extend the
season?
Allow more time for crops to
mature
Grow different varieties
Move toward year-round production
and income potential
Fresh greens in the winter
4. Frost-free period
We’ll define the length of a frost-
free period as the number of days
between the date of the last 32°F
temperature in the spring and the
date of the first 32°F temperature in
the fall.
5. What’s “freezing”?
The National Weather Service
defines a “freeze” as occurring
“when the surface air temperature
is 32°F or below over a widespread
area for a climatologically
significant period of time (greater
than one hour).” (U.S. Department of
Commerce, 2005)
6. How long are our frost-free
periods?
Lots of variation among periods for
the last 100 years
Some years have had frost-free
periods of over 150 days
(approximately 5 months)
Other years have had frost-free
periods of less than 90 days. (Reno data)
KEY: lots of varibility, so you have
to watch the weather predictions!
7. Do frost-free periods ever
change?
For the 30-year period of 1971-2000,
the average date of the last 32°
temperature in the spring was May
21 while the date of first 32°
temperature in the autumn was
October 3 (134 days).
8. 1991-2005
The date of last 32° reading was
May 3, and the date of first 32°
reading in the autumn was
October 19
The average length of the frost-
free period grew from 134 days
(for 1971-2000) to 168 days for the
more recent 15-year period
This is an increase of a full
month!
9. Hard freeze
A hard freeze is sometimes defined
as occurring on a date when the
temperature drops to 28°F
But…you can expect damage when
temps drop to 32°F
10. City Frost-Free
Days
Carson City 90 - 116
Elko 57 - 87
Ely 53 - 81
Fallon 106 - 131
Lovelock 111 - 140
Reno 85 - 125
Tonopah 107 - 147
Winnemucca 75 - 107
Based on historical data indicating 90% (first number)- 121
Yerington with temperatures above50% (second number)
82 to 32°F.
probability of consecutive days
http://www.wrcc.dri.edu/summary/Climsmnv.html
11. Cold damage
Plants lose heat faster than the air!
Anything that reflects the radiating
heat back down will prevent or at
least greatly reduce frost formation
(for example, clouds)
12. Season Extension:
Start with cultural practices
Site selection and microclimates
Soil and moisture content
Windbreaks and shade
Irrigation
Cultivar selection
Transplants
13. Take advantage of
microclimates
Some areas around your property
warm up faster in the spring, stay
cooler or warmer in the summer, or
are protected from the wind
South-facing slopes will be warmer
Cold air settles into valleys
17. Shade fabric
Creates a cooler microclimate to
help prevent bolting and bitterness
Faster germination of cool-weather
fall crops
Shading 30 -50% in midsummer can
lower leaf temps by 10 degrees or
more
18. Managing moisture
Plants under drought stress can be
more susceptible to cold damage
Water holds warmth and releases it
slowly
So…water before frost is expected
19. Alter soil temperatures
Use clear plastic mulch to warm soil in
spring and retain extra heat in fall
Cover the edges of the plastic with soil
to anchor it in place
Temps increase by 8 to 14 degrees to a
depth of 2 inches and 6 to 9 degrees to
a depth of 4 inches
20. Mulch to insulate plants
Organic mulches such as straw also
decrease radiated heat and conserve
moisture, preventing cold (and hot)
extremes
21. Choose hardy crops
Start and end with cold-hardy
vegetables that tolerate frost
Look for short-season varieties
Other varieties are specially
adapted to growing in long, hot
days, extending your growing
season into the summer (ex. slow
bolting lettuces)
Read seed packets and catalog
descriptions
22. Spring crop transplants
Start plants early
Start seeds of tomatoes, peppers,
and eggplants 8 weeks early
Start seeds of cole crops about 4 to
6 weeks early
Start vine crops 1 week early
23. Fall crop transplants
Start plants for late-season crops in
late summer
Seed a second season of quick-
maturing vegetables, such as snap
beans, peas, greens, radishes, cole
crops, and turnips later in the
season
Grow cold-tolerant species in the
fall
24. Examples of late-season
crops
Kale
Collards
Lettuce
Spinach
Mustard greens
Arugula
Broccoli
Broccoli rabe
Mache
Beets Lettuce, kale and rabe
Peas
25. Winter harvest
Decreasing levels of light in
fall/winter slow plant growth to
near-dormancy
Lowest light in December and
January
Many cold-weather crops must be
harvested by the end of fall
26. Vegetable planting dates
Planting dates depend upon the
plant cold-hardiness.
Semi-hardy vegetables can be
planted two to four weeks before
the average last killing frost date of
May 15, or in cool fall temps
27. Vegetable planting dates
Plant frost-tender and cold-
sensitive vegetables after the last
frost date
Buy transplants, or start from seed
indoors from mid-March through
mid-April
Earlier transplanting can be done
when hotcaps, row covers or other
protection is used
28. More tips
Grow cold-
tender herbs,
dwarf fruit
trees, etc. in
containers that
you can move
indoors
30. Protect from early and late frosts
Cover early and late season
plantings with mini-greenhouses
made from clear plastic, old
window sashes set on hay bales, or
fabric row covers
Vent the covers on warm days to
prevent excessive heat buildup
31. • Use hot caps
in spring
• Need to vent
them
• Works for
small plants
• Blocks some
light
37. Fall freeze protection
Extend the covering all the way to
the ground so cold air can’t seep in
Put in place before sundown
Especially useful for the first few
frosts when warmer weather is then
expected
38. More tips
Cover hardy root crops with a 6- to
12-inch-thick layer of straw or other
organic mulch in fall to prevent the
soil from freezing.
Harvest as needed throughout the
winter.
39. Row covers
•Agribon, Reemay,
Harvest Guard, etc.
•Come in different
weights
Can provide 3
to 5 degrees of
frost protection
40. Row covers
Warm and speed the growth of
seedlings in spring
Slow the evaporation of soil moisture
Protect plants from wind, heavy rain,
and hail
Heavier fabrics provide more frost
protection but block more light
41.
42. Row covers
Keep pests off plants but need to
remove covers for insect pollination
Protect late summer crops from fall
frost
Protect crops from hot temperatures
and burning sun rays
Must anchor with soil, wood, rocks,
etc.
46. Cold frames
Can provide 5 – 7 degrees of
protection
Can be used in the spring to start
plants or in the fall for cold-hardy
crops
Use old windows or glass doors to
make your own
No standard size; keep width
narrow enough that you can easily
reach across
47. Can add black containers
filled with water to store
heat for the night
48. Cold frames
Don’t use wood treated with
preservatives!
Slope the lid to the south
Place on south side of house
49.
50. Cold frames
Provide for ventilation of excess
heat when temps rise above 55
degrees
Cover to protect against freezing,
or stack straw bales against the
frame
51.
52. Cold frame tips
Ventilate on warm days
Checktemperatures with a
thermometer
Protectduring freezing
weather: Remember that cold
frames give only 5-10 degrees of
warmth.
53. More cold frame tips
Water: make sure plants aren’t
getting too much or too little
water.
Hardening plants: open the lid of
your cold frame longer and longer
each day
55. Benefits of low tunnels
About five to six weeks earlier
production in the spring
Several weeks later production in
the fall
Some protection from insects and
foraging animals
Some protection from extreme
weather conditions, such as strong
winds, hail or frost
http://simplegoodandtasty.com/2010/05/25/tunnel-farming
56.
57.
58. Tips for low tunnels
Use UV-stabilized tubing
Don’t expect protection from hard
freezes
Plan for access and ventilation
59. Building materials to construct one mini
tunnel for 40-inch by 30-foot raised bed
Quantity Item Description Unit Price Total
200 feet 1/4-inch nylon rope $0.08/ft $16.00
1,8-ft by 38- 6-mil greenhouse poly $0.13/sq
$39.52
ft sheet film ft
1/2-inch sch 40 PVC
80 foot $0.22/ft $17.60
pipe
20 foot 1-inch sch 40 PVC pipe$0.44/ft $8.80
44 2-inch wood screw $0.05 $2.20
2 3/8-inch by 2-foot rebar $0.75 $1.50
2 Eye screw $0.50 $1.00
*Prices may vary depending on
Total $86.62
location, etc.
http://www.noble.org/Ag/Horticulture/RaisedBedGardening/mini_tunnel.html
60. High tunnels (aka hoop
houses)
Big enough to walk into
Size them to meet your needs
Plant in-ground or in raised beds
Does not have an added source
of heat or ventilation
Can extend the season through
the winter by up to three zones, or
a month in the fall
61. Orient in an east-west direction to
maximize sunlight, but also consider
62. Structural elements
Can be mobile or fixed in place
End walls are most important to
strength
Can incorporate an opening for
ventilation in the end walls
Hoops no more than 4 feet apart
Peaked-roof (vs. U shape) stronger
in snowy climates
63. Structural elements
Use a center support to increase stability
Use 6-mil, greenhouse-grade, UV
stabilized polyethylene
Roll-up sides allow for ventilation
64. How to Build a High Tunnel (video)
http://www.youtube.com/watch?v=
am1Tso2l3kc
Also see
http://www.extension.org/pages/18356/low-cost-high-tunnel-
construction
65.
66.
67.
68.
69.
70.
71.
72.
73. Minnesota study
On average, tunnel vegetables such
as lettuce, tomatoes and cucumbers
were harvested about six weeks
earlier than those grown in the open,
while peppers were ready nearly ten
weeks ahead.
Many of the tunnel plants produced as
much as double the output of the
outdoor crops
74. What about winds?
High tunnels placed perpendicular to
prevailing winds typically receive the
most damage, so consider placing
parallel
The best protection against uplift is to
ensure that posts are driven at least
24 inches into the ground
Use stretch cord over the top of the
plastic from one side to the other,
every fourth rib
75. What about snow?
A high tunnel built from ribs of 20 foot
pipe bent to create a 14 foot wide X 6
foot high structure will withstand only
about 10 psf
This is about 2 inches of water as
snow
Might be as little as one foot of snow
76. More tips for dealing with
snow
Use a center roof rib
Orient the structure so prevailing
winds blow the snow off the high
tunnel
Remove the plastic in the winter if not
under production
Brush off snow using a long-handled
broom (carefully!)
77. NRCS High Tunnel Pilot
Project
Eligibility Requirements:
To qualify, the applicant must:
◦ be an agricultural producer
◦ install the high tunnel(s) on cultivated land
which includes existing gardens, irrigated
hayland and irrigated pasture
◦ have raised or sold $1,000 worth of
agricultural products
http://www.nv.nrcs.usda.gov/programs
/NV_high_tunnels.html
78. Greenhouses
Walk-in, permanently placed
The most expensive solution
Usually have venting and heating
systems (requires energy inputs but
gives more control)
In some areas, can be used year
round
Can add mass for thermal storage
(water barrels, etc.)
79. Do your homework
Many types on the market
Many plans available as well
Look at the alternatives before
investing
Can use to insulate your house when
attached
Consider a solar greenhouse
82. Greenhouses
Walk-in, movable
Less expensive
Can be disassembled
and stored away when
not in use
Usually used one to two
months before the last
frost in the spring.
83. Whatever you do…
Keep good records!
Consider a journal that includes
varieties, dates planted, dates
matured, freezes, etc.
Nurture your soil with lots of organic
amendments
Keep a map of what was planted
where
85. Why rotate crops?
Breaks the cycle of disease and pests
Helps to maintain adequate nutrients
Can help improve soil structure
(alternate deep-rooted plants with
shallow-rooted plants)
Can decrease costs
86. Considerations in crop rotation
schemes
Heavy feeders: leafy veggies,
brassicas, corn
Soil conserving/improving: legumes
(peas and beans)
Lighter feeders: bulb and root crops,
many herbs
88. Another simple rotation
Root Legumes
crops, and
onions brassicas
Sweet Nightshades
corn, -
cucurbits tomatoes
and peppers
89. End-of-season maintenance
Clean up! Remove dead vegetation
and windfalls, compost healthy
material. Remove fallen fruit and dead
leaves to decrease pest problems.
Think about cover crops to enrich and
stabilize soil (winter rye, triticale)
90. End-of-season maintenance
Enrich garden beds with compost or
manure; add mulch or leaves; think
about nutrient needs for your specific
crops
Collect dried seed from open
pollinated flowers & veggies
Clean out cold frames for winter use
91. End-of-season maintenance
Clean and oil lawnmower, other
garden equipment and tools before
storing for winter
Take equipment in to be sharpened
(mower blades, pruning equipment)
Drain and store hoses carefully to
avoid damage from freezing
Clean, sand and oil garden tools
before storing them for the winter