garden under cover: winter vegetable production in low tunnels
TRANSCRIPT
Garden Under Cover: Winter Vegetable
Production in Low Tunnels
Cathy Rehmeyer, PhD Four Petal Farm
www.gardenundercover.com www.motherofahubbard.com
Four Petal Farm Because Locally-Grown Should Always Be ‘In-Season’
Banner, Kentucky
Our Climate: Plant Hardiness Zone 6b
Winter Lows: 2014 = -8 F 2015 = -14 F Average snow (season total) = 24 inches
Eliot Coleman
Winter growing methods: Open field and low tunnels covered with
fabric row cover (no clear plastic!)
Urban Ag. Holler Ag.
Farmer’s Market
W i n t e r
C S A
Online Storefront
Restaurant Sales
Micro Greens and Edible Flowers
Farm to School
Value-Added Products
Summer is our “down-time.”
Find a niche and make it work for you!
Winter Growing:The Essential Elements
1. CHOOSING THE RIGHT PLANTS
The garden still freezes — the key is selecting the right crops that can take it.
January 8, 2014
January 9, 2014
January 14, 2014 (-8 F the previous week)
January 24, 2014
Five Cold-Tolerant Crop Families• Alliaceae (Leek, onion, garlic, shallots)
• Amaranthaceae (Beet, orach, spinach, swiss chard)
• Apiaceae (Carrot, celeriac, cilantro, fennel, parsley, parsnip)
• Asteraceae (Catalogna, chicory, endive, escarole, lettuce, radicchio, salsify, scorzonera)
• Brassicaceae (Arugula, Asian greens, broccoli, Brussels sprouts, cabbage, cauliflower, mustards, radish, rutabaga, kale, turnips)
Crops Appropriate for Low Tunnel Production: Root Crops• Root Crops (carrots, rutabaga, daikon radishes, beets,
turnips, parsnips, scorzonera, salsify, parsley root)
Crops Appropriate for Low Tunnel Production: Greens
Crops Appropriate for Low Tunnel Production: Overwintered Brassicas
Heirloom varieties are generally more cold hardy
Superior cold-hardiness
• selection by gardeners for centuries/decades prior to cheap transportation and the grocery store
Winter Vegetables (in decreasing order of cold hardiness)
Varieties (open-pollinated italicized)
Mache Vit, Verte de Cambrai
Scallions Evergreen Hardy White
Parsnips Harris Model, Hollow Crown
Asian greens* Chinese Thick-Stem Mustard, Serifon
Cabbage, overwintering Deadon, Marabel, January King
Spinach, savoy types Tyee, Bloomsdale Longstanding
Kale, Scotch types Dwarf Blue Curled, Winterbor
Leeks, winter varieties American Flag, Blue Solaise, King Sieg
Fava beans, small-seeded Diana, Sweet Lorane
Broccoli, sprouting Matador, Santee, Early Purple Sprouting
Garlic Inchelium Red, Georgia Fire
Collards* Blue Max, Champion
Rutabagas Laurentian, Purple Top, Gilfeather
Kale, Napus types Ragged Jack, Russian Frills
Cauliflower, overwintering Galleon, Mumbles
Asian greens* Senposai, Komatsuna
Carrots Napoli, Snow White, Danvers 126
Turnips, roasting Golden Globe, Purple Top
Kohlrabi Early White Vienna, Winner
Winter radish Black Spanish, Violet de Gournay
Daikon Bravo, Misato Rose, Green Luobo
Endive/escarole/catalogna De Meaux, Green Curled Ruffec
Brussels sprouts Jade Cross, Diablo
Lettuce Marvel of Four Seasons, Winter Density
Swiss chard, green-stemmed Verde de Taglio
Arugula Astro, Sylvetta
Beets Cylindra, Red Ace
Orach Orach Pink
Turnips, salad Hakurei, White Egg, Tokyo Market
Pak Choy* Tatsoi, Mei Qing Choi, Joi Choi
Radicchio Bel Fiore, Palla Rossa
Cabbage, standard Late Flat Dutch, Stonehead
Broccoli, standard Calabrese, Premium Crop
Cauliflower, standard Snowball, Violetta Italia
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Winter Vegetables (in decreasing order of cold hardiness)
Varieties (open-pollinated italicized)
Mache Vit, Verte de CambraiScallions Evergreen Hardy WhiteParsnips Harris Model, Hollow CrownAsian greens* Chinese Thick-Stem Mustard, SerifonCabbage, overwintering Deadon, Marabel, January KingSpinach, savoy types Tyee, Bloomsdale LongstandingKale, Scotch types Dwarf Blue Curled, WinterborLeeks, winter varieties American Flag, Blue Solaise, King SiegFava beans, small-seeded Diana, Sweet LoraneBroccoli, sprouting Matador, Santee, Early Purple SproutingGarlic Inchelium Red, Georgia FireCollards* Blue Max, ChampionRutabagas Laurentian, Purple Top, GilfeatherKale, Napus types Ragged Jack, Russian FrillsCauliflower, overwintering Galleon, MumblesAsian greens* Senposai, KomatsunaCarrots Napoli, Snow White, Danvers 126Turnips, roasting Golden Globe, Purple TopKohlrabi Early White Vienna, WinnerWinter radish Black Spanish, Violet de Gournay
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Mache (Corn Salad)
• $5 for only 3.5 oz in Krogers and Whole Foods!
• Very cold-tolerant – stays beautiful with minimum protection (Agribon-19 or GG17)
Baby Asian Greens and Kale• Salad Greens =
$5 - $6 per 8 oz bag
• Grown under AG-30 or GG34
Root Crops• $3-4 per bunch • Grown under AG-30 or GG34
(Hakurei turnips an exception)
Cabbage• $4-5 per head, with
leaves • Savoy and January
King types overwinter
Purple Sprouting Broccoli• continuous production
of broccoli florets beginning late March
April 2, 2012
Variety REALLY matters…
Purple 68 Napoli
Winter Growing:The Essential Elements
1. CHOOSING THE RIGHT PLANTS
2. CROP PROTECTION – Dessication is more damaging to plants than cold
temperatures – protect them from winds – Gro-Guard 34 (equivalent to Agribon 30) is
ideal – add additional layer when <15 F*
– no more clear plastic in production system to minimize labor (e.g., venting on clear days)
Low Tunnel Construction and Management
Low Tunnels made with 1/2” EMT
PVC vs EMT
• Cost comparable, but MAJOR difference in structural integrity
Bending EMT with a Johnny’s Selected Seeds’
Quick Hoops Bender ($59)
Low Tunnel Construction
Rebar isn’t required — use with caution!
Opening and Closing Low Tunnels
Row Cover is Gro-Guard Medium Weight (GG34) from Deerfield Supplies
Extra-Low Low Tunnels
Mini-hoops for salad greens
Space 2-3 ft apart for snow load readiness
Mini-hoops for salad greens
Winter Salad Mix = hardy Asian greens, mache, kale
High Tunnel $1.40 per ft2
EMT Low Tunnel $0.23 per ft2
x 2400 ft2 = $3360
x 2400 ft2 = $552
Replace plastic every 4 years = $0.20 per ft2
Replace cover* every 4(?) years = $0.03 per ft2
* = Polypropylene Fabric
Need low tunnels in high tunnels in extreme weather
Why low tunnels?Inexpensive!!!
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Cost Comparison for 4 ft X 50 ft bed (200 sq ft)
EMT Wire Hoops
Cost of Hoops 11 hoops @ $2.35 each$25.85
22 hoops @ $0.48 each$10.56
Cost of Row Cover $15.42 per 60 ft length X 2$30.84 $15.42
Sandbags 0.70 0.70
Total Cost $57.39($0.28 per sq ft)
$26.68($0.13 per sq ft)
($0.11/sq ft relative to high tunnel covered paths)
($0.23/sq ft relative to high tunnel covered paths)
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Why low tunnels?
Topography
Why low tunnels?
Snow Happens
Effect of snow cover on low tunnel temperatures
Snow
Ambient temperature
0 F
No snow cover
Why Low Tunnels?
Versatility
• hoops can be used to support insect barriers in spring/summer
• shade cloth support
Why Low Tunnels?Mobility
• Avoid accumulation of soluble salts
• At winter’s end, tunnels are easily moved to help other crops get an early start
• Cover crops (reduce dependence on compost/fertilizer)
Soil Fertility Matters: 50% of garden in cover crop in any given season
WINTER SPRING SUMMER FALL
Block 1 winter salad mix cover crop (Ph) cover crop (Ph) alliums & kale
Block 2 alliums & kale alliums & roots alliums & roots (B) roots
Block 3 roots cover crop (CS) cover crop (CS) cover crop (R,V)
Block 4 cover crop (R,V) cover crop (R,V) solanaceae roots & Asian greens
Block 5 roots & Asian greens
spring salad mix cover crop (H) cover crop (O,CC,F)
Block 6 cover crop (O,CC,F)
corn & beans corn & beans fall salad mix & peas
Block 7 cover crop (R,P) cover crop (CS) cover crop (CS) heading brassicas
Block 8 heading brassicas peas & potatoes cover crop (B) cover crop (O,CC,V,P,F)
Block 9 cover crop (O,CC,V,P,F)
cover crop (O,CC,V,P,F)
winter squash cover crop (R,V,P)
Block 10 cover crop (R,V,P) cover crop (R,V,P) sweet potatoes winter salad mix
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Why Low Tunnels?
• Reduced dependence on irrigation — row cover is somewhat permeable to water
• Jump start on spring planting with relatively drier beds
Why NOT Low Tunnels?• Areas subject to frequent
straight-line winds would be challenging
• Plant hardiness zone 5 and colder? Only try plants with greatest cold tolerance.
• Areas with continuous snow cover (tunnel access is difficult) or extended #nights in sub-zero temperatures
Winter Growing:The Essential Elements
1. CHOOSING THE RIGHT PLANTS
2. CROP PROTECTION – Dessication is more damaging to plants than cold
temperatures – protect them from winds – Gro-Guard 34 (equivalent to Agribon 30) is ideal
– add additional layer when <15 F*
3. DELAYING HARVEST – Plants must reach desired size before really cold
temperatures and less light arrive
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Goal: Have crops nearing maturity (or the size desired) near onset of
“Persephone Days”
Use days to maturity to count back from Persephone Days onset (+2-3 weeks
slower growth in fall)Enter the date of your latitude’s last 10 hour
day:
11/22
Crop Days to Maturity
Transplant? (1 = yes, 0 = no)
Target date to sow seed
(direct, or for transplants)
Target date to set transplants in field
Carrot, ‘Napoli’ 58 0 September 11 0
Broccoli, ‘Arcadia’ 63 1 August 9 September 6
Turnip, ‘Hakurei' 38 0 October 1 0
Brussel Sprouts, ‘Jade’ 120 1 June 13 July 11
Carrot 75 August 25 0
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb MarArugula :::: ::…. ^^^ ^^^ ^^^ ^ |Asian greens :::: ::::::: :…. ^^ ^^^ ^^^ ^^^ ^ |Beets :::….. .. ^^ ^^^ ^^^ ^^^ ^Broccoli, standard t tt TT ^^^ ^^^ ^Broccoli, sprouting t tt TT ^^^ ^^^ ^^^ ^^^ ^Broccoli raab (rapini) ::: ^^^ ^^^ ^^^ ^^^ ^Brussels sprouts tttt TT ^^ ^^^ ^Cabbage, Asian ::: ^^^ ^^^ ^^^ ^^Cabbage, heading t tt TT ^^^ ^^^ ^Cabbage, overwintering ttt tt TT ^^^ ^^^ ^^^ ^Carrots :: :::::… .. ^^^ ^^^ ^^^ ^Cauliflower, standard tttt t TT ^ ^^^ ^|Cauliflower, overwintering tttt t TT ^ ^^^ ^^^ ^^^ ^^^ ^Celeriac tt T TT ^^^ ^^^ ^| ttttttCollards :::::: ….. ^^ ^^^ ^^^ ^^^ ^Daikon :::: ::… ^^^ ^^^ ^^^ ^^^Endive/escarole/catalogna tt ..TT ^^^ ^^^ ^^^ ^^^ ^Garlic bbb bbGreens, specialty* :: :::…. ^^^ ^^^ ^^^ ^^^Kale :::::::: ::.…. ……. ^^ ^^^ ^^^ ^^^ ^Kohlrabi tt :::T T ^ ^^^ ^^^ ^^^ ^Leeks t tt T TT ^^^ ^^^ ^^^Lettuce :::::::. ……. .. ^^ ^^^ ^^^ ^^^ ^Mache ::: ::::… ^^^ ^^Mustard greens ::::: ::::… ^^ ^^^ ^^^ ^^^ ^Onions, bunching :::::Onions, perennial bbb bb
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Soil Temperatures for Germinating Vegetable SeedsMinimum (°F) Optimum Range (°F) Optimum (°F) Maximum (°F)
Bean, Fava 40 60-95 70 85Beet 40 50-85 85 95Broccoli 40 45-85 85 95Cabbage 40 45-95 85 100Carrot 40 45-85 80 95Cauliflower 40 45-85 80 100Celery/Celeriac 40** 40-75 70 80Chard, Swiss 40 50-85 85 95Collards 40 60-95 85 100Endive/Escarole 35 35-85 70 80*Kale 40 65-85 80 100Kohlrabi 40 65-85 80 90Leek 40 45-95 75 90Lettuce 35 40-80 75 85*Mache 40 40-70 68 70Mustard/Asian greens 40 45-85 80 100Onion 35 50-95 75 95Parsnip 35 50-70 65 85Pea 40 40-75 75 85Radish 40 45-90 85 95Radicchio/Chicory 45 45-85 70 85*Rutabaga 40 45-85 80 85Salsify/Scorzonera 40 65-75 70 -Spinach 35 50-70 65 85*Turnip 40 60-105 85 105Garden Under Cover: Winter Vegetable Production in Low Tunnels
Not all seeds are created equal.• There can be CONSIDERABLE differences in cold-hardiness in a given
variety from different companies.
• Find seed suppliers nearest your own climate
• colder climate seed sources aren’t always better
• be aware that some companies may source their seed elsewhere
• Patronize seed companies/growers that specialize in winter growing
• Johnny’s Selected Seeds, Osborne Seed Company, Adaptive Seeds, Wild Garden Seed, High Mowing Organic Seeds
• Even’ Star Farm (available via Southern Exposure Seed Exchange)
• Seed Savers Exchange Yearbook and local seed swaps
Why grow your own seeds?• Cost-savings?
• perhaps, depending on scale
• micro greens seed stock
• Control of seed supply
• kale seed shortage in 2014 and 2015
• seed no longer listed by company
• crop failure due to disease outbreak/GMO contamination in major seed hub (beets in Skagit Valley)
Choosing varieties for winter growing/seed saving
Least Profitable Most ProfitableBroccoli Collards Arugula Carrots
Brussels sprouts Kale (baby) Asian greens Kale (mature)
Cabbage Lettuce (baby) Beets Turnip
Cauliflower Mache Daikon/Winter Radish Rutabaga
Kohlrabi Parsnips Endive/Escarole
Onions, yellow Spinach Garlic
Swiss chard Leeks
Broccoli, sprouting Lettuce (mature)
Onions, bunching
Radicchio
Garden Under Cover: Winter Vegetable Production in Low Tunnels
Low Tunnel Management
• Heat is your enemy, not cold! – Tunnel temps >65° F shift plant cold tolerance
and promote disease • vent tunnels on warm sunny days, or completely
remove covers in warm stretches • Thicker row cover isn’t necessarily better – Light is equally important to temperature in
winter growing – heavier row covers limit transmission
Consider your area’s unique frost/freeze climatology
National Weather Service, Jackson, KY. http://www.weather.gov/jkl/frostfreezeclimo
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