PREFACE
This is not a suggestion. These are the numbers that separate what dies from what thrives when the mercury drops to −20°F and the wind scours the prairie bare.
The pergola stands through January. Its timber was seasoned for this.
CROP 01: TURNIP (Brassica rapa subsp. rapa)
Species authority: Wikidata Q3916957 | Natural product of Brassica rapa subsp. rapa
TURNIP (WINTER STORAGE)
ROOT VEGETABLE · BRASSICA
PLANTING WINDOW
AUG 15 – SEP 5
DAYS TO MATURITY
56–62
HARVEST BEFORE
OCT 15
SOIL TEMP MINIMUM
35°F
OVERWINTER DEPTH
18"
SUCROSE ACCUMULATION
18–22%
FROST TOLERANCE
−10°F (bare)
SNOW COVER REQ
≥6"
SPRING RECOVERY
21 days
CRITICAL FAILURE MODE: Planting after September 10 yields insufficient sucrose accumulation. Root dies at −5°F without protective mulch.
SURVIVABLE CONDITION: 18" soil burial + ≥6" snow cover maintains root viability at −20°F ambient. Sugar concentration reaches 22% by December 21.
CROP 02: CARROT (Daucus carota subsp. sativus)
CARROT (LONG-KEEP)
ROOT VEGETABLE · APIACEAE
PLANTING WINDOW
JUL 20 – AUG 10
DAYS TO MATURITY
70–80
HARVEST BEFORE
NOV 1
SOIL TEXTURE
LOAM/SILT
ROW SPACING
12"
CAROTENE PEAK
SEP 25 ± 3d
FROST TOLERANCE
−5°F (mulched)
OVERWINTER MULCH
8–12" straw
SPRING HARVEST
APR 15+
CRITICAL FAILURE MODE: Clay soil causes forked roots. Frost before September 20 destroys beta-carotene synthesis. Loss rate: 94%.
CROP 03: KALE (Brassica oleracea var. acephala)
SCOTT'S GREEN KALE
LEAFY GREEN · BRASSICA
PLANTING WINDOW
JUN 15 – JUL 5
FIRST HARVEST
SEP 10
PEAK FLAVOR
DEC 21
CROWN HEIGHT
4" above soil
WIND EXPOSURE
≤15 mph sustained
GLUCOSINOLATES
↑ 300% post-frost
FROST TOLERANCE
−15°F (hardened)
HARVEST METHOD
LOWER leaves only
CONTINUOUS YIELD
NOV–MAR
SURVIVABLE CONDITION: October 15 hardening required. Plants exposed to gradual cooling accumulate antifreeze proteins. Sudden freeze below −10°F kills meristem.
CROP 04: PARSLEY (Petroselinum crispum)
FLAT-LEAF PARSLEY
HERB · APIACEAE
PLANTING WINDOW
APR 15 – MAY 10
ESTABLISHMENT
60 days
WINTER PROTECTION
Cold frame mandatory
MIN SOIL TEMP
28°F
HARVEST CYCLE
Outer stems weekly
APIOLE CONTENT
↑ 2.1x post-frost
FROST TOLERANCE
−8°F (protected)
COLD FRAME HEIGHT
18"
LIFESPAN
Biennial (yr 2 = flower)
CRITICAL FAILURE MODE: Unprotected parsley dies at 20°F. Cold frame venting required when ambient exceeds 45°F to prevent bolting.
Keokuh County, January. The blue jay knows the grain cache. So do we.
PROTOCOL: SNOW PACK MANAGEMENT
INSULATION CALCULATOR
THERMAL PHYSICS
SNOW DENSITY (typical)
0.1 g/cm³
THERMAL CONDUCTIVITY
0.0001 cal/cm·s·°C
REQUIRED DEPTH FOR −20°F
6"
REQUIRED DEPTH FOR −30°F
12"
SOIL HEAT CAPACITY
0.2 cal/g·°C
FREEZE FRONT RATE
0.8"/day
SAFE ROOT ZONE
Below 12"
MONITORING INTERVAL
Daily at 0600
FIELD ACTION: When forecast predicts −25°F, pile loose straw to 8" over root crops. Compact lightly with gloved hand. Replenish after wind event.
AGENT-LEGIBLE DATA TWIN
Complete planting calendar, thermal constants, and crop metadata:
field-guide.json
RETURN TO HUB
Complete planting calendar, thermal constants, and crop metadata:
field-guide.json