From silking to grain fill, reproductive corn growth stages represent the development of the corn kernels that will ultimately make up your corn crop yield. Understanding how corn moves through final growth stages and how to manage for optimal yield is foundational to a successful season.
R1 corn growth stage
In the R1 corn growth stage, also known as “silking,” grains of pollen from the tassel fall on the ear’s long, hair-like silks, each of which is connected to the ovule of a potential individual corn kernel. The pollen grains germinate and grow pollen tubes that reach down the silk to fertilize the ovules. At this crucial stage, each fertilized ovule can increase yield, and any interference now will result in yield loss. It can take two or three days for all the kernel ovules on a single ear to be fertilized, and during this time, pests like corn earworm and corn rootworm may feed on silks. Using Bt corn hybrids and in-furrow products such as Nurizma® Insecticide to combat corn rootworm larvae, you can help mitigate rootworm damage from the start.
R2 corn growth stage
R2 corn, also known as “blister” stage corn, generally occurs 10 to 14 days after silking. R2 corn begins to produce small, watery kernels. Silks begin to brown and dry, especially if the corn plant is suffering from heat or water stress. During this stage, make sure each plant receives adequate water, as it has a direct correlation to grain fill. Continue to monitor and manage silk-feeding pests such as corn rootworm, earworms, grasshoppers, army worm and Japanese beetles.
R3 corn growth stage
The milk stage of corn growth arrives 18 to 22 days after silking when kernels begin to take on their signature yellow color. The phase gets its name from the milky fluid that fills kernels. Kernels will continue to grow through cell expansion and starch accumulation. Corn borer is a common threat during this stage and, if left unchecked, may cause damage that has an economic impact.
From late vegetative corn growth stages through R3 corn is the optimal time for fungicide applications. Veltyma,® Headline AMP®, and Priaxor® fungicides both provide protection from yield-robbing infections as well as plant health benefits for more efficient crop growth and stress reduction. Priaxor can be effective for V5-V8 plant health and disease protection, while Veltyma can provide superior plant health and protection from key diseases including tar spot, southern rust, and gray leaf spot with applications from the VT through the R3 stages.
R4 corn growth stage
Roughly 24 to 28 days after silking comes the dough stage. Kernels reach 50% of their dry weight as the process of grain fill continues.
R5 corn growth stage
Thirty-five to 42 days after silking, we’ve reached the dent stage, in which the cob takes on a darker red color. Note that a frost event during this phase will slow the drying period for the corn, potentially delaying harvest timing.
R6 corn growth stage
By the R6 stage of growth, the corn plant has reached full maturity and the growing season is nearing its end. During this phase, sometimes called the black layer, starch progresses to the bottom of the kernel and a black line can be seen along the base. By this point, the kernel has reached its maximum dry weight and, when sufficiently dry, is ready to be harvested.
Corn harvest
When your corn is fully grown, it will need to be artificially dried to safely harvest and store. Corn should generally be dried to 15% moisture (wet basis) for store for up to six months and 13% moisture to safely store through the summer or beyond one year.¹
For additional information on corn growth stages and input recommendations, contact a nearby extension office agent, or your regional BASF representative.
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Endnotes
- Ileleji, Klein. “Grain Quality – It’s Time To Check Your Stored Grain.” Pest&Crop Newsletter, Purdue, 10 Mar. 2022, extension.entm.purdue.edu/newsletters/pestandcrop/article/grain-quality-its-time-to-check-your-stored-grain/. Accessed 4 Feb. 2026.
