Corn crops are one of the most adaptable members of the grass family. Every fall, more than 14 billion bushels of corn are harvested by North American farmers. This popular crop is grown for various uses including food production, starch, corn-derived alcohol, corn syrup, animal feed, and more.
Producing high-yielding, quality corn crops requires a strong understanding of their growth throughout production. A deep understanding of each stage of development will help you better manage the crop from planting to harvest. Certain fertility decisions are only effective at specific stages of development, and factors like the climate and soil conditions can impact the evolution of growth. Thus, it is important to better understand corn’s growth stages and development cycle to better manage crop production while meeting your goals. Knowing what stage of growth your crops are in will also allow you to better manage their health, assess crop quality, and determine the best time to harvest.
The stages of corn development can be broken into two parts: vegetative stages and reproductive stages. Vegetative stages can be defined by leaf collars—where the number of leaf collars helps to identify the growth stage (VE, V1, etc.). Reproductive stages begin after the tassels have emerged and silking begins.
Vegetative Stages
In the vegetative stages, shoots emerge from the soil, leaves emerge from the plant, ear and tassel shoots begin forming, and flowering begins. The vegetative stages end when the lowest branch of the tassel is visible.
Reproductive Stages
During the reproductive stages, silk extends on the exterior of husk leaves, maximum plant heights are reached, the quantity of kernels is determined, silks darken and dry out, kernels yellow and fill with starch, and corn crops reach maturity.
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VE – Emergence
Emergence happens when the first leaf or the spike leaf appears above the ground. The seed absorbs water and oxygen for fermentation. The radicle root emerges from the tip of the kernel. Soil temperature should be 50-55 degrees Fahrenheit with moisture present for optimal emergence. Planting depth is critical for this stage—too deep can delay emergence and too shallow can create a weak plant.
V1 – First Leaf
During the first leaf stage there is one lead collar visible. The leaf collar is found at the base of the leaf. The stages are defined by the uppermost leaf with visible collars. Scouting is suggested at this stage for early weeds and pests.
V2 – Second Leaf
Nodal roots are emerging farther into the ground at this stage and seminal roots begin to grow.
V4 – Fourth Leaf
Nodal roots are farther in the ground and taking up more volume. Leaves are developing off the stem of the plant. At this point of growth, the leaves are primarily growing more than the root system.
V6 – Sixth Leaf
Six leaves with collars have formed. The growing point emerges above the soil surface, the plant continues to grow, height increases, and nodal roots are established in the lowest, below-ground nodes of the plant. Scouting is suggested again at this stage for weeds and pests. Nutrient uptake begins to increase rapidly at this stage, and nutrient application should be timed properly. Ear and tassel shoots begin forming, so nutrient deficiencies at this stage can impact later yields.
V10 – Tenth Leaf
During this stage, brace roots have developed in the lower-above ground nodes. Nitrogen and water demands are at their highest, and plants are easily susceptible to drought, heat, and nutrient deficiencies. Weed control is critical during this stage of growth because of early competition. Maximum number of rows per ear is being determined at this time. The number of potential maximum kernels per row is determined from about this stage to tasseling (VT).
V14 – Fourteen Leaf
Rapid growth happens during this stage. Flowering will begin in approximately two weeks. Plants are sensitive to heat and drought stress. Growers should scout during this stage for root lodging issues and diseases.
VT – Tassel
During tasseling, kernels start developing in rows and the final potential ear size is determined. The last branch of the tassel is visible. Silks may or may not have emerged. Nitrogen and water demands are high for the crops. Heat and drought will affect the number of kernels. During this stage, growers should scout for insects and diseases.
R1 – Silking
During this stage, flowering begins and silk is visible on the outside of the husks. The first silks are attached to potential kernels near the base of the ear. Maximum plant height is achieved, pollination is occurring and the potential number of kernels is being determined. Nutrient needs are high for fertilization.
R2 – Blister
At this stage, silks darken and are drying out. Kernels are about 85% moisture and will soon fill with starch. Environmental stress can reduce yield potential and final grain count.
R3 – Milk
Silks are dried out. The kernels are turning yellow and a milk-like fluid can be squeezed out of the kernels. Any stress at this point will cause kernel abortion at the tip of the ear.
R4 – Dough
Starch materials inside the kernels have a dough-like consistency. Nutrients and starch are accumulating with kernels being at 70% moisture. Environmental stress at this point can cause reduced yield by reducing kernel size and cause kernels to be shallow or chaffy. Impact of frost on grain quality can be severe with 25-40% yield.
R5 – Dent
At this stage, most of the kernels are dented. Moisture is declining to about 55%. Stress will reduce kernel weight. Many growers will harvest for silage soon.
R6 – Maturity
At maturity, a black layer forms at the bottom of the kernel, blocking any movement of dry matter and nutrients from the plant to the kernel. Kernels will be around 30-35% moisture and are physiologically mature. At this stage, grain is not ready for storage, but maximum dry weight bas been attained. Disease and pests can result in physical damage and grain loss. Scouting is suggested for ear drop from pest damage.
