Penn State Corn and Soybean Management

Latest Planting Dates for Various Hybrid Maturities in Pennsylvania

The maps on the links below are designed to provide some guidance for selecting corn hybrids based on their growing degree day requirement and climatological data for the state developed from 30 year weather station records throughout the state.

Hybrid Maturity Map Images:

Guidelines for using the hybrid maturity map images:

Select a growing degree day (GDD) map link above that corresponds to the hybrid maturity group for the seed you are planting. We have found that the actual GDDs for hybrid maturity are often less than the ratings, especially in later planted situations.

Maturity Rating (Days)	Estimated GDD requirement (Planting-Phys. Maturity)
75-80	1800-1900
80-85	1900-2000
85-90	2000-2100
90-95	2100-2200
95-100	2200-2300
100-105	2300-2400
105-110	2400-2500
110-115	2500-2600
115-120	2600-2700

Estimate the potential that a corn crop planted on the projected planting date will be subject to a frost before maturity.
Consider this information in deciding whether to switch to an earlier maturing hybrid. Corn can be killed by frost before maturity and still produce grain but the test weight may be reduced and the drydown may be delayed. For some applications, such as high moisture corn or silage, this may still be acceptable. Corn that is killed by frost before the half milk line stage (approx 150 GDDs prior to maturity) may encounter more effects on grain yield and quality from a killing frost. For silage, the GDD requirement of hybrids could be reduced by approximately 150 GDDs.
Avoid planting very early hybrids ( <2000 GDD) in late planted situations in the southern half of Pennsylvania. These hybrids were bred for cool northern climates and often lack the heat and drought tolerance required for these environments.

These maps were produced in collaboration with ZedX, Inc. (http://www.zedxinc.com/)