The Stages of Growing Sweet Corn

Germination

• When a corn seed is planted into wet soil, the seed absorbs water through its coat. Germination is triggered once the seed absorbs approximately 30 percent of its weight in water. Within two days of being exposed to moist soil, the seed has germinated and is beginning to move into the vegetative stage of growth.

Vegetative Stages

• The first vegetative growth stage is Emergence (VE), in which the radicle (root) emerges from the germinated corn seed. The radicle is followed by the coleophile (shoot), which is pushed to the surface of the soil by the elongation of the mescotyl (the first interlode of the plant). Vegetative growth of the plant continues on through tasseling (VT). The stages of growth between VE and VT are designated with numerals to indicate a particular stage of growth. For instance, during V1, the lowermost leaf of the plant forms a visible collar. In V2, the second leaf forms a collar. And so on. V7 indicates the formation of the seventh leaf collar. During the V7 and V8 growth stages, kernel row determination begins. At V9 and V10, the stalk and tassel begin rapid growth. The sweet corn plant reaches VT when the tassel is fully emerged. This occurs approximately 125 days after VE.

Reproductive Stages

• The reproductive stages of growth for the sweet corn plant are designated numerically from R1 through R6. R1 (Silking) begins when silk is visible. In the R2 (Blister) stage, the kernels are white and look like a blister. The kernels have turned yellow on the outside in varieties that are yellow, with a white inner milk-colored fluid by stage R3 (Milk). At R4 (Dough), the inner kernel fluid thickens to a pasty consistency. The kernels begin to dent in stage R5 (Denting), and the cob has turned dark red. The kernels have reached full maturity by stage R6 (Physiological Maturity), which occurs approximately 55 to 65 days after R1.