Extension Logo
Extension Logo
University of Minnesota Extension

Growth and development

By understanding how corn grows and develops, producers can more confidently assess crop damage, estimate if it will recover and apply herbicides and other crop inputs at the best time.

A corn plant’s growth stage is either part of the vegetative (V) or reproductive (R) periods.

corn seedling emerging
Corn seedling emerging (VE)

The vegetative stage begins when the seedling emerges (VE) and continues until tasseling (VT), when the reproductive stage begins. During the vegetative stage, leaves develop and grow, the stalk forms and reproductive structures (ear and tassel) begin to form.

Timing of growth stages

The vegetative stage occurs between early May and early to mid-July. About 1,300 heat units (growing degree days) accumulate during this time period.

The reproductive stage begins with pollination, and ends when grain has fully formed. The reproductive stage begins about early to mid-July and ends about mid-September. Approximately 1,100 heat units accumulate during this time period.

Predicting development

A growing degree day is a measure of heat accumulation calculated by subtracting 50 from the daily average temperature. It uses a base of 50 because very little, if any, corn growth occurs when the temperature is below 50 degrees Fahrenheit.

Temperature is one environmental parameter that drives plant growth. You can use heat units to predict important corn development events such as tasseling and maturity.

Vegetative growth stages

corn stalk base split in half
The growing point is the small triangle near the top of the stalk tissue. It stays below the soil surface until about the five-leaf stage.

The photograph shows a young corn plant at the four-leaf stage (V4) that has been split. The growing point is a group of rapidly dividing cells that produce each new leaf from its base.

A new leaf forms approximately every four days until this group of cells begins to produce reproductive structures (ear and tassel). Usually 18 leaves form on each corn plant.


How to determine vegetative growth stage

Currently, two methods – counting collars and downward pointing tips – adequately describe vegetative growth stages.


Reproductive growth stages

Reproductive (R) growth stages begin with fertilization of the floret (pollination) and end when the grain reaches its maximum dry weight. This later stage is called physiological maturity (PM). Grain moisture content is about 32 percent at PM.

We describe reproductive stages based on degrees of kernel development.


Jeff Coulter, Extension corn agronomist, Dale R. Hicks, emeritus Extension agronomist; Seth L. Naeve, Extension soybean agronomist and David Nicolai, Extension educator

Reviewed in 2021

Page survey

© 2023 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer.