Are you ready to grow healthy and ‘sweet’ sweet corn? This article will break down the six growing stages, and what you must do at every stage.
The first harvestable phase is the R2 stage.
This is when the entire plant is rapidly growing and its leaves are fully developed.
During this phase, the kernels become a little like a blister on a cob. The plant’s starch accumulation continues.
The next major phase, the R3 stage, is called the “milk” stage because the starch inside the kernels becomes white and watery.
The plant is still preparing to reproduce during this time.
The first leaf of sweet corn appears at R1 and the second leaf emerges at R2. A healthy leaf will have a visible collar on the tip and a rounded tip. After the silks emerge, the plant is in the “blister” stage.
At this point, the kernels will begin to grow, and the stalk will be completely developed. The plant will continue to grow until it reaches vegetative maturity, which can be between four and eight feet tall.
At this stage, the plant’s root system continues to grow until it reaches the vegetative stage VN.
At each stage, the plant will send out nodal roots that will anchor it in the soil. By this time, the plant will reach its full height, or vegetative maturity, which is between four and eight feet tall. During this stage, it is best to harvest the plant before it reaches the R4 stage.
Stage 1: Germination of Sweet Corn
The first phase of the sweet corn germination stage is known as the V10 stage. The plant continues to grow rapidly and dry matter accumulation increases.
The length of the ear shoots (ears) is also shortened to 50 GDDs per leaf. Tassel formation occurs all over the plant.
The plant is now beginning to increase its moisture and nutrient requirements. The tassels will eventually form into ears.
The next phase is the reproductive stage, which begins at the R3 or milk phase. This is recognized by the presence of milky liquid in the kernels and visible collars.
During this stage, the plant is still preparing to reproduce, and farmers will harvest the sweet corn to eat. In addition to being harvested for food, sweet corn is also prepared to seed. During this phase, a few leaves will form on the plant.
The first two leaves of sweet corn will appear during the R3 stage, while the second leaf will appear about a week later. This stage is also known as the R4 stage and begins to solidify starch in the kernels.
The increased amount of starch also leads to a decrease in water content in each kernel. In addition, the endosperm in the sweet corn kernel has developed fully. The fourth stage is called the V5 stage. This final phase is when sweet corn is harvested for fresh consumption.
Stage 2: Vegetative Growth
The vegetative growth stage of sweet corn begins six to eight weeks after the plant emerges from its dormant state (VE). The number of leaves that the plant bears is known as its leaf count, and it varies by variety.
The number of collars indicates the plant’s leaf stage. Four or more collars mean that the plant is in the V4 stage. Acorns are typically at least twenty-four inches tall and have a diameter of 3.5 cm.
This phase has several substages, which are sometimes grouped together because the processes are similar. The first of these is called the milk stage and is recognized by the presence of the male reproductive part (VT), or tassel.
During this phase, sweet corn kernels are fully extended, and they contain a milky liquid. The tassel will eventually fertilize each kernel. The first two leaves will be visible.
The second vegetative growth stage of sweet corn is called the emergence stage. In this stage, the first leaf appears.
The collar of each leaf is clearly visible. In this stage, the plant’s leaves will continue to develop until it reaches their vegetative maturity, which is approximately four to eight feet tall. The third and final stage is the flowering stage, during which time the plant is largely inactive.
Stage 3: The VT Tassel Emergence
During the VT Tassel Emergence stage of Sweet Corn, the ear shoots, which are the potential ears, are visible outside of the husk.
The pollen then moves down the silk and into the ovule. This process occurs on the silk and takes around 24 hours.
This growth stage is influenced by environmental conditions. Stress and lack of moisture can hinder the pollen transfer, and the leaves are dry and inflexible.
The vegetative growth stage (VG) of corn is the appearance of the plant’s leaves. It is characterized by the presence of collars on the lower stems. The first and the final VT stages are also referred to as emergence and tasseling.
During the VT Tassel Emergence stage, the plant is about knee-high. It has developed tiny side buds. These buds will form the ears and the tassel. By the end of the VT Tassel Emergence stage, it is seven feet tall and has developed ovules on each ear.
The VT Tassel Emergence stage of Sweetcorn is defined by the appearance of the tassel. It is the male reproductive part of the plant. When the VT is visible, it is in a mature plant.
The tassel is the lowest branch of the tassel and eventually fertilizes each kernel. During this stage, the plant is more vulnerable to hail damage than at earlier stages, and the tassel may appear even before the final leaf stage.
Stage 4: R1 Silking of Sweet Corn
The R1 Silking stage of sweet corn is the most critical stage in the growing process. The kernels are still filled with a milky white fluid, and the outside of the fruit is yellow.
The inner portion of the kernel is milky white and contains 85% moisture. The plant is also most sensitive to stress during this time, and frost can significantly reduce yield potential by causing kernel abortion.
Early frost can also prevent the accumulation of dry matter and prematurely cause the growth of black layers.
After the vegetative growth stage has finished, the corn plant will enter the reproductive growth stage. There are six reproductive stages, identified by numerical designations.
At the R1 Silking stage, the kernels are covered with silks and capture pollen grains that fall from the stalk.
These pollen grains continue to grow and develop down the silks, becoming the beginnings of corn kernels. The next two to three days are needed for the plant to achieve physiological maturity.
The next stage of the development process is known as the Milking stage. The kernels of corn at this stage are mostly yellow with a white milky fluid inside. The milky fluid is a sign of ovule fertilization.
Once the ovule is fertilized, it will grow into the kernel. Then the R2 Silking stage occurs, which is a week or two after the Milking stage. After the milking stage, the sweet corn plant will move into the Blistering stage, and then reach the maturity of the R1 Silking stage.
Stage 5: Sweet Corn R2 Blister
The vegetative stages of Sweet corn can be classified according to the number of leaves present on the plant. Each of these leafing stages has its own significance and represents a pivotal point in the plant’s development and yield.
Cooler soil temperatures delay the V5 stage and tassel formation, delaying the harvest and putting the crop at risk for frost damage.
Flooding during the earlier stages of the plant can cause the fruit to die and may even prevent the kernels from developing. The later stages are less susceptible to floods as most of the growth takes place above ground.
The kernels at the R2 stage are whitish “blisters” that are visible on the cob and are filled with abundant clear fluid.
The ear silks have begun to dry out. The endosperm is fully developed and the first embryonic leaf has formed. The kernels can easily abort during this stage if there is stress applied to them.
The moisture content is approximately 85% and the thermal time is 960 GDDs, averaging around five days in late April plantings in Indiana.
After reaching the R2 stage, sweet corn will begin its reproductive phase. The first step in this process is called silk and occurs when one or more silks extend beyond the husk.
The next stage of the reproductive phase is called the blister stage.
During this stage, the kernels will be visible and resemble oozing blisters. This is the time when the kernels are ready for harvesting and can be used for nourishment.
Stage 6: R3 Milk Phase of Sweet Corn
The R3 Milk stage of sweet corn is when the kernels begin to develop. At this stage, the kernels are very small, with a clear, milky fluid inside.
The silks are already darkening and starting to dry.
Approximately 85% of the kernel is water, and the kernel size will continue to decrease until harvest. This milky texture is the result of accumulating starch. The stress from the growing process also affects the size of the kernels.
The R3 Milk stage of sweet corn is the next developmental stage, where the kernels have begun to develop.
The first step of this phase is when the first silk appears on the husk. At this time, the kernels begin to harden, and a white, watery layer forms on each one. This layer is called the milk line, and it slowly advances to the tip of the kernel. At this point, the corn is ready to be harvested.
The R3 Milk stage of sweet corn is when the starch and sugars in the kernels have reached a certain amount of concentration.
The starch and sugars in the kernels solidify and reduce the amount of water in each one. At this time, the R3 Milk stage is when fresh, edible corn is harvested. In this stage, the silks have begun to dry out and the endosperm is fully developed.