Corn Growing Degree Day (GDD / GDU) & Maturity Calculator
Calculate daily accumulated Growing Degree Units (GDU) using the standard 86/50 modified method, predict corn crop growth stages (VE, V6, VT tasseling, R1 silking, R6 black layer), and assess fall frost risk.
Corn Hybrid & Daily Temperatures
°F
Capped at 86°F under standard 86/50 method.
°F
Floor at 50°F base biological threshold.
GDU
Total accumulated heat units since planting.
Current Phenology Status
R1: SILKING & POLLINATION
Daily Accumulated Heat Units
23.0 GDU
Adj: 84°F max / 62°F min
GDU Remaining to Black Layer
1,350 GDU
50.0% to R6 maturity
Corn Growth Stage GDU Milestones
VE (Seedling Emergence):
100 – 120 GDU
V6 (Growing Point Above Ground):
475 GDU
V12 (Ear Size Potential Determined):
815 GDU
VT / R1 (Tasseling & Silking):
1,300 – 1,400 GDU
R3 (Milk Stage):
~1,700 GDU
R5 (Dent Stage):
2,100 – 2,250 GDU
R6 (Physiological Black Layer Maturity):
2,700 GDU (111 CRM)
USDA & Iowa State Modified 86/50 Method
Crop Climatology
Daily GDD = [(Tmax* + Tmin*) / 2] - 50. Daily highs above 86°F are capped at 86°F because corn photosynthetic efficiency plateaus. Daily lows below 50°F are adjusted up to 50°F because biological corn development stops below this baseline.