When does corn grow?

New! Click or tap the image to view the new Growing Corn guide

Joseph Masabni, Assistant Professor and Extension Horticulturist, and Patrick Lillard, Extension Assistant, The Texas A&M System

Sweet corn is a member of the grass family. In smaller gardens, it should be planted in square blocks instead of long rows to improve cross-pollination between corn stalks. Like most vegetables, corn will grow best in areas with plenty of sunlight.

Corn is one of the plants grown in the traditional Native American vegetable technique call the Three Sisters. The other two plants in the Three Sisters are beans and squash, and each had its role in this companion planting tradition. Corn served as a support for the vining beans. Squash served as a ground cover, preventing weeds from growing. Beans provided natural fertilizer for all.

Site selection

Corn can tolerate many soil types but prefers well-drained soils with a pH between 5.5 and 7.0. In sandy soils or soils with a low pH, corn may suffer from magnesium deficiency.


Soil preparation

Remove weeds, rocks and trash, and work the top 8 to 10 inches of soil before planting. Work the soil only when it is dry enough not to stick to garden tools.


Use 2 to 3 pounds of fertilizer, such as 10-10-10, for every 100 square feet of garden area. Spread the fertilizer evenly over the soil and work it into the soil 3 to 4 inches deep. Rake the soil to smooth the surface.


Sweet corn is a warm-season crop and must be planted after the soil warms and there is no more danger of frost. If you have room, plant again when the first corn plants have three to five leaves. This usually takes 2 to 3 weeks. You will need 1 to 2 ounces of seed for every 100 feet of row. Do not use seed saved from last year’s sweet corn as these seeds will not grow a good crop. Sweet corn grows best when planted in several short rows instead of one long row. This makes it easier for the corn plants to pollinate, and good pollination is necessary for ears of corn to have plump, juicy kernels.

Figure 1. Plant corn in several short rows, not in one or two long rows.

Plant the corn seeds about 1 inch deep and 3 to 4 inches apart in the row. Space the rows 2½ to 3 feet apart. After the plants are up, thin them to 1 foot apart. If you plant them closer, your corn will have small, poorly-filled ears (Figs. 1 and 2.)

Figure 2. Poorly filled corn is caused by poor pollination.


Water sweet corn as needed to keep it from wilting. Do not let corn suffer from lack of water when the kernels are forming.

Care during the season

Hoe or till the soil just under the surface. Hoe the weeds off just below the soil’s surface. Deep hoeing will cut the corn roots, which are close to the top of the soil.

When the plants are about 2 feet tall, apply 1 cup of fertilizer for every 10 feet of garden row. Scatter the fertilizer evenly between the rows and mix it lightly with the soil. Water after fertilizing (Fig. 3.)

Figure 3. When corn is about 2 feet tall, scatter 1 cup of fertilizer for every 10 feet of row and water it in.


If a few of your corn plants are stunted, they may have a viral disease and should be removed to keep the virus from spreading.

Click or tap to view corn diseases chart


Corn is ready for harvest about 3 weeks after the tassel grows on top of the corn plant. Corn is ripe when juice from the kernels is milky white, the silk on the ears has turned dark brown, the kernels get large, chewy and pasty like dough.

The best time to pick corn is in the early morning or evening when it is cool. To harvest the ears, hold the stalk below the ear and twist the tip of the ear toward the ground until it breaks off. Cook the corn right away, or store it in the refrigerator until mealtime. Corn loses flavor and nutrients quickly when left at high temperature. Watch the corn closely because the quality changes fast.


Corn has small amounts of many vitamins and minerals and is best when cooked immediately after picking. It can be cooked either on or off the cob. Remove husks, silk and bad spots just before cooking. Corn which is past its best quality is still good as cream-style corn.


Store corn in the husk. Place it uncovered in the refrigerator for 1 or 2 days. Corn stored for more than 2 days loses its sweetness.


Old corn plants are good compost to add to the garden soil. They will break down much faster if shredded before composting.

Download a printer-friendly version of this page: Growing Sweet Corn (pdf)

View this publication in Spanish: Cómo cultivar maíz dulce

New! How to Grow Corn

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How to grow: Sweet corn

At a glance

Ease of culture: Moderate
Where: All zones
Best climate: Warm to hot conditions
When: Spring and summer
Spacing: 25cm
Harvest: 8-10 weeks
pH: 5.5-7


• Sweet corn likes warm to hot conditions and can be grown in all parts of Australia when conditions are favourable
• Daytime temperatures need to be consistently above 15°C for planting
• Spring and summer are the best seasons for planting in most areas. You can plant all year round in tropical areas.


• Corn needs plenty of sunshine to thrive – at least 6 hours a day
• Strong winds can damage tall plants so choose a protected spot.


• Corn is a demanding crop nutritionally, so the soil needs to be very well-prepared and enriched
• Dig over the soil to a spade’s depth and incorporate a wheel-barrow load of compost and/or well-rotted manure per square metre
• Add organic fertilisers, such as blood and bone and pelletised chicken manure as well, and till it all through
• Hill the soil to improve drainage
• Water soil well and let sit for a week before planting

Box: Fresh Seed

Corn seed stored more than a year quickly loses viability, which reduces germination success when planting. Buy fresh corn seed every year and be sure to check the ‘sow by” date on the pack before taking it home.


• Corn seed is best sown directly in the soil, but it can also be raised in pots or tubes in a warm spot and planted after germination. This allows gardeners in cool areas to get an early start. It’s also a good option when weather conditions are wet, which will cause seed to rot and fail.
• Sow seed into moist soil 5-7 mm deep, 25cm apart, with 60cm spacing between rows. Plant 2-3 seeds per hole and thin out unwanted seedlings later. These can be transplanted to fill gaps.
• Water soil well and don’t water again until seeds germinate or they will rot. This does not apply when raising seed in pots, but do allow the mix to almost dry out between watering
• Seeds germinate in 10-14 days.
• Corn cobs are pollinated by wind. Pollen is shed from the male flowers at the top of the plant and floats downwards to make contact with the female flowers or ‘silks” at the end of the immature cobs.
• Plant corn seed in blocks of three or more rows, rather than long single rows. This allows for a more even dispersal of pollen, producing cobs with even and consistent kernel production.
• Aim to establish 30 or more plants per sowing
• Plant a new crop every 4-6 weeks to guarantee an ongoing supply during the growing season.

Watering and fertilising

• Corn plants are large and fast-growing, so need regular feeding and watering
• Gradually increase the regularity and depth of watering as the crop develops
• Liquid feed the crop once per week with a mix of diluted kelp and fish emulsion at half strength
• When plants reach approximately 50cm high, hill the soil around the base of plants using a nutrient-rich blend of soil, compost and well-rotted manure, and a little blood and bone. This encourages more roots to develop, supporting plants in strong winds and increasing valuable uptake of moisture and nutrients.
• Follow up with a thick layer of pea or lucerne straw to help combat weeds and retain soil moisture


• Cobs are ready for harvesting about 3 weeks after flowering commences.
• The first sign of maturity is when the silks at the top of the cobs have turned brown.
• Peel back some of the protective husk and pierce a single kernel with your thumb nail. It should release a milky liquid. If it’s clear it needs more time. If there’s no liquid, the sugars have converted to starch, which means it’s over-ripe. This spoiling conversion can happen quickly, so check cobs daily.
• Twist cobs with a sharp movement downward to remove from plant.
• Most plants will form two or more cobs
• If cobs are ready, but you’re not, they will store well in the fridge for a week or so.

How Long Will it Take Corn to Emerge?

By Elwynn Taylor and Roger Elmore, Department of Agronomy

It’s an understatement to say that March in Iowa was much warmer than normal (Figure 1). Although only a few record high daily temperatures were set, the average monthly temperature set a new record by a substantial margin. The consistent warm weather encouraged a few to plant corn as early as mid-March. Soil temperatures state-wide reached 50 F by March 15. Although not a first historically, it was a full month before soils normally warm to 50 F at the 4 inch depth.

The warm soil temperatures encouraged rapid germination and seedling emergence — by the third week of March. With April came a “hard” freeze (low air temperatures below 28 F) and a cooling of the soils to levels that did not sustain rapid seedling development.

Planting corn into cool soils increases variability not only of emergence, but also of plant to plant sizes and development stages. In addition the freeze likely destroyed some or all of the leaves of emerged plants; but, since seedlings’ growing points were still well below ground, plants likely recovered and stands (plant populations) were unaffected. Frosted plants typically recover at different rates resulting in variable growth and development. Variability in plant size — whether from cool soil temperatures or from frost – will affect plant-to-plant competition and reduce yield.

Corn typically requires 90 to 120 Growing Degree Days (GDD) from planting to emergence. Of course this GDD range assumes adequate soil moisture and varies with planting depth, tillage system and residue cover. As a rule of thumb, if 120 GDD have accumulated since planting and seedlings haven’t emerged, check the condition of planted seed.

You may track GDD accumulations for the Corn Belt location of your choice by clicking on ‘single site graphs’ on the Mesonet website. Your specific planting date information is easily selected from the drop-down windows. Choose the weather station near your farm from the list or select by clicking the “dot on the map” near your farm. Track the GDD accumulation at your location (a blue line is produced) and compare it to the normal GDD accumulation for your location (a red line is displayed). It is helpful to also make a graph of last year to give you an idea of average GDD accumulation to help visualize the similarities and differences between this year and the past year.

You need to remember that GDD’s are calculated based on air temperatures using the 86/50 method typical for corn production. Using that method, if air temperatures remain at or below 50 F, emergence will not occur.

Since GDD calculations are based on air temperatures, four-inch soil temperatures may actually better predict seedling emergence than accumulated GDD’s. The Mesonet provides a daily update of both the Iowa soil temperature and GDD. Laboratory studies have shown that for most corn hybrids grown in the Midwest, seedling emergence is about three weeks if the soil temperature is 51 F and is about one week if the daily soil temperature holds near 70 F (Figure 2).

After emergence, evaluate the surviving plant stand carefully whether or not you expect good emergence and seedling survival. Both poor stands and plant-to- plant variability lower yield potential. Depending on the potential date of replant though, keeping the surviving stand — albeit of variable plant heights and development — may still be the best option. (See: Replanting Information)

Figure 1. Most Iowa locations enjoyed at least one March day of temperatures reaching 80 F. At Ames the average daily high was 64 F, eclipsing the old record of 58 F set in 1968. Climodat information from mesonet.agron.iastate.edu.

Figure 2. If the soil temperature is averaging 50 to 55 F (10-12.8 C) at the time of planting, corn may take three weeks to emerge. Temperatures averaging 60 F (15.6 C), may have emergence in 10 days to 12 days. Soybean emergence usually requires that soils be about 10 degrees warmer than for corn although soybean does begin to respond at 50 F. Data from Elwynn Taylor, Iowa State University.

Elwynn Taylor is extension climatologist and can be reached at [email protected] or by calling (515) 294-1923. Roger Elmore is a professor of agronomy with research and extension responsibilities in corn production. He can be contacted by email at [email protected] or (515) 294-6655.

How To Grow Corn – How To Grow Your Own Corn

Corn (Zea mays) is one of the most popular vegetables you can grow in your garden. Everyone loves corn on the cob on a hot summer day drizzled with butter. Furthermore, it can be blanched and frozen so you can enjoy fresh corn from your garden in the winter.

Most methods for corn planting are similar. The difference depends on type of soil, available space, and whether or not you need to amend the soil for growing corn.

How to Grow Your Own Corn

If you want to grow your own corn, you need to know how to grow corn from seed. There aren’t many people who actually start corn plants first; it just isn’t feasible.

Corn enjoys growing in an area that allows for full sunshine. If you want to grow corn from seed, be sure you plant the seeds in well drained soil, which will increase your yield dramatically. Make sure your soil has a lot of organic matter, and fertilize before you plant the corn. Good soil preparation is very important.

Wait for the temperature of the soil to reach 60 F. (18 C.) or above. Make sure there have been plenty of frost-free days before putting the corn into the soil. Otherwise, your crop will be sparse.

If you’re thinking about how to grow corn from seed, there are only a few rules to follow. First, make sure you make your rows 24-30 inches (60-76 cm.) apart from each other. Plant the corn 1 to 2 inches (2.5 to 5 cm.) deep in the soil about 9 to 12 inches (23-30 cm.) apart.

Mulch will help keep your corn weed-free and will retain moisture during hot, dry weather.

How Long Does it Take for Corn to Grow?

You might be wondering, “How long does it take for corn to grow?” There are many different varieties of corn and a couple of different methods for corn planting, so you can plant 60-day, 70-day or 90-day corn. When most people think about how to grow corn, they are thinking in terms of their own private stash of corn.

One of the different methods for corn planting is to have a continuous growing season. To do this, plant several types of corn that mature at different time intervals. Otherwise, plant the same kind of corn staggered by 10-14 days so you have a continuous crop.

Harvesting time is dependent on the particular type grown and how it will be used.

Once Corn Is Planted, How Long Will It Take To Come Up?

Corn typically requires 90 to 120 Growing Degree Days or GDDs from planting to emergence. Of course this range assumes adequate soil moisture and varies with planting depth, tillage system and crop residue cover. “As a rule of thumb, if 120 GDDs have accumulated since planting and seedlings haven’t emerged, you should check the condition of planted seed ASAP,” advises Clarke McGrath, Iowa State University Extension field agronomist at Harlan in western Iowa.

WATCH CAREFULLY: Keep an eye on emerging corn seedlings, and also check the corn you’ve planted that hasn’t yet emerged. “It will be curious to see how stands turn out this spring, given our cold snaps,” says ISU agronomist Clarke McGrath.

Some of the early planted corn this year, the corn that went in April 4 to 12 or so, is now spiking. It has had enough GDD’s despite the cold temperatures, says McGrath, who authors the “Corn-Soybean Insight” column for ISU Extension each month in Wallaces Farmer magazine.

Another rule of thumb is corn in 50-degree F soils takes about 20 days to emerge, and this year that has held pretty true. “As soil temperatures get to around 60 degrees F, corn comes up in about 10 days, which is hopefully where the corn we plant in the next week or so will end up,” he notes.

Track growing degree day accumulations for your fields
You can track GDD accumulations for the Corn Belt location of your choice by clicking on ‘single site graphs’ on ISU’s Mesonet website. Your specific planting date information is easily selected from the drop-down windows. Choose the weather station near your farm from the list or select by clicking the “dot on the map” near your farm. Track the GDD accumulation at your location (a blue line is produced) and compare it to the normal GDD accumulation for your location (a red line is displayed). “It’s helpful to also make a graph of last year to give you an idea of average GDD accumulation to help visualize the similarities and differences between this year and last year,” he adds.


You need to remember that GDD’s are calculated based on air temperatures using the 86/50 method typical for corn production. Using that method, if air temperatures remain at or below 50 F, emergence will not occur. “We hope this isn’t a continuing issue now that we are in early May,” says McGrath.

Soil temperature may be the better predictor of emergence
Since GDD calculations are based on air temperatures, four-inch soil temperatures may actually do a better job of predicting seedling emergence than accumulated GDD’s. The Mesonet provides a daily update of both the Iowa soil temperature and GDD. Lab studies have shown that for most corn hybrids grown in the Midwest, seedling emergence takes about three weeks if the soil temperature is 51 F and it takes about one week if the daily soil temperature holds near 70 F.

“Cold and wet soils like we currently have will slow down germination and emergence once corn is in the ground,” McGrath noted on May 2. “These conditions can also give soil microbes that attack seedlings the advantage—so exercise patience and watch the weather forecast when getting ready to plant.”

What about corn that’s already in the cold ground?
“So far, I am optimistic,” he says. “What I’ve dug up has looked pretty healthy, and the weather is improving. I remember there was a lot of excitement a year ago when we had a lot of corn in the ground when our May 1 blizzard came through. There were some cold days after that, but then it warmed up and the corn came out of that situation quite well in the end. I suspect unless things really get cold again for an extended period of time, we will have good stands this spring.”


McGrath describes some things farmers, agronomists and crop consultants have seen in prior years in similar weather conditions to what we’ve had this spring:

Imbibitional chilling—This is a common term for the chilling effect seeds may go through when they absorb water, especially when soil temperatures are less than the mid-50’s for an extended time. “The last few days of April and the first two days of May this spring, soil temperatures have been from the mid-40’s to low 50’s at the 4-inch depth in our area, and I’d guess we’ll gain ground on that over the next week based on the weather forecast,” he says. “Keep in mind that with seed around 2-inches deep, temperatures can fluctuate a little more than at the 4-inch depth, so with some sun, soil temperatures often bounce back up this time of year.”

On the other hand, it takes more BTU’s of energy to raise the temperature of saturated soils vs. dry soils, slowing any warming. “So given the cold rains we’ve had this past week, we’ll likely spend another 4 or 5 days with our planted corn suffering soil temperatures around 50-degrees or so,” McGrath observed on May 2. Corn seed absorbs around a third of its weight in water early in the germination process. If this water is cold enough (exact temperatures vary by source, but upper 40’s to low 50’s are often mentioned), cell walls can become “brittle” and even rupture.

“When this happens, we’ve seen all sorts of impacts,” he adds. “Seed that just swells and never continues growth, sometimes corkscrewed seedlings, ruptured coleoptiles, leafing out underground, seedling death and other interesting but not good phenomenon. The good news is that often this impacts a relatively small percentage of a field; only occasionally do we see enough problems to warrant any action. So far I haven’t seen or heard of too much of this occurring this spring.”


Wide temperature swings— “We sometimes see ‘corkscrewed’ seedlings in conditions like we have now,” says McGrath. “But more often we see these in drier soils and with wide temperature swings.” Recall the discussion about water, soil and BTU’s earlier in this article. Former ISU Extension agronomist Roger Elmore provided some research information that talked about soil temperature swings of around 27-degrees F or more being a primary culprit in causing this.

“Again, typically it is a small percentage of a field and growers may not even notice the corkscrewed seedlings in most years,” adds McGrath. “Given our wet soils this spring, corn planted on the early-April planting dates is more likely to suffer the imbibitional chilling than the temperature swing ‘corkscrewing’— but things can change quickly. I say once again, however, my early scouting of cornfields this spring hasn’t shown many problems so far.”

Insect injury—The longer a seed or seedling is small and growing slowly, the greater the odds of a pest finding it and attacking it.

Diseases—Cold, wet soils slow corn growth and leave it exposed to disease pathogens for a longer time. Some pathogens thrive in these conditions (pythium comes to mind) so while the corn struggles, pathogens have a better shot at infecting the corn plants.

Herbicide injury—This can also be more of an issue when seedlings are under a lot of stress and are growing slowly. “Experience tells me that usually plants grow through this with little, if any long term impact,” says McGrath. “Also, while we sometimes point the finger to herbicide injury when we see slow or uneven corn emergence, the real culprit is simply poor conditions.”


He adds, “As a fertilizer/chemical dealer in my earlier career, I diagnosed tough-looking fields as having herbicide injury. In subsequent years as we moved away from using pre-emerge residual herbicides and moved to using total post programs, we’d see the same symptoms in the absence of any soil-applied herbicides. Lesson learned. While early season herbicide injury to seedlings does happen, it probably isn’t as common as we think. Conditions like these do increase the odds of issues, though, so careful investigation is warranted for any field that exhibits problems that may appear to be herbicide related.”

Today’s corn hybrids are durable, can take a lot of stress
The good news: Today’s corn hybrids are incredibly durable and can take a lot of stress based on the improved genetics alone. Advanced fungicide and insecticide seed treatments that seed companies offer will increase the odds of getting a healthy stand. “While these seed treatments have a limited window of protection, looking at the growing degree trends for early May—odds are we’ll see the corn take off quickly, helping it fight any early season insects and diseases,” says McGrath.

“The bottom line is, there are no guarantees that the earliest planted corn will be a perfect stand. But experience and the calendar tells us that if weather conditions improve this coming week, the odds are in our favor,” he sums up. “The best thing farmers and crop consultants can do is keep an eye on the planted acres and monitor seedling development, and be sure to take some emergence and stand counts.”

‘Evening complex’ proteins help corn grow taller at night

Farmers and other astute observers of nature have long known that crops like corn and sorghum grow taller at night. But the biochemical mechanisms that control this nightly stem elongation, common to most plants, have been something of a mystery to biologists — until now.

In this week’s early online publication of the journal Nature, biologists at the University of California, San Diego report their discovery of a protein complex they call the “evening complex” that regulates the rhythmic growth of plants during the night.

More importantly, the biologists show how this protein complex is intricately coordinated through the biological clock with the genes that promote stem elongation in a way that could enable plant breeders to engineer new varieties of crops that grow faster, produce greater yields of food or generate more biomass per acre of land for conversion into biofuels.

“This discovery gives us a molecular understanding of how the biological clock is regulating cyclic growth in plants,” said Steve Kay, dean of UC San Diego’s Division of Biological Sciences, who headed the research effort. “And it instantly gives us a handle on how we might manipulate and control plant yield or biomass deposition.”

While most people assume that plants grow at a slow and steady rate throughout the day and night, Charles Darwin and others more than a century ago observed that they actually grow in spurts late at night, with plant stems elongating fastest in the hours just before dawn.

“Plants actually grow rhythmically,” said Kay. “Some plants, like sorghum, have the ability to elongate a centimeter or more each night.”

The UCSD biologists initially focused their attention on three genes from a tiny mustard plant called Arabidopsis, which is used by geneticists as a laboratory model for plants. When they are disabled by mutations, these three genes disrupt the plant’s biological clock and promote both stem elongation and early flowering.

“These three genes have been of intense interest because the loss of function in each one of them kills the biological clock, causes a long hypocotyl, or juvenile stem, and tends to cause early flowering,” said Kay. “We thought that maybe their function was related. So this investigation was basically started to figure out what these three genes do.”

The answer to that seemingly simple question took the biologists more than six years to disentangle. Their efforts were led by three postdoctoral fellows in Kay’s lab: Dmitri Nusinow, Anne Helfer and Elizabeth Hamilton.

“Circadian clocks control the timing of an extraordinary variety of developmental and physiological processes in humans and other species, but figuring out how they do this is tough,” said Laurie Tompkins, who oversees biological clock grants at the National Institutes of Health’s National Institute of General Medical Sciences, which funded the research. “Arabidopsis is ideal for this sort of analysis, since researchers can use a variety of sophisticated genetic and biochemical tools to study molecular interactions at different times of day and then easily observe the tiny plant’s development.”

Because the three genes — Early Flowering3 (or ELF3), ELF4 and LUX — have biological activities that peak in the early evening, the UCSD biologists wondered if the three genes acted together in a protein complex. Through a series of experiments in yeast cells, they determined the three genes produced proteins that did interact with one another, but in a specific way. ELF3 served as a docking protein that brought together ELF4 and LUX, but the latter two did not interact with each other without ELF3’s help.

This protein complex was dubbed the “evening complex” by the UCSD scientists, who verified in Arabidopsis that not only did the biological activities of the three components of this protein complex peak in the evening, but so did the formation of the evening complex itself.

The researchers then sought to answer the question of what the physiological role of this protein complex could be in plants. One main clue pointed them in the right direction: When any one of the three genes controlling this protein complex is disabled, plants end up with grossly elongated stems.

“This protein complex is clearly acting like the brakes on growth,” said Kay. “So when we mutate any one of these genes the plants elongate much more.”

In another set of experiments, the researchers demonstrated that the evening complex puts the brakes on the activity of two genes in plants — PIF4 and PIF5 — that are important in promoting plant growth.

“What we show in our paper is that the evening complex binds to the promoters of PIF4 and PIF5 and, at the end of the day and through the early part of the night, prevents the plants from growing,” said Kay. “And when the levels of the evening complex begin to drop, PIF4 and PIF5 are expressed and drive plant expression programs that support stem elongation, and the brakes on plant growth are taken off.”

In this new model of plant growth developed by the scientists, PIF4 and PIF5 control the gas pedal that activates plants to grow, while the three genes that produce the evening complex act as the brakes and work with the plant’s biological clock to permit the most rapid growth in the late evening and early morning hours.

“Nobody knew how this cyclic regulation of plant growth worked on a molecular level, but this must be one of the major mechanisms,” said Kay. “This really gives us a molecular understanding of how the biological clock is regulating cyclic growth in plants.”

Why plants time their diurnal cycle to grow most rapidly late at night and in the wee hours of the morning is still a mystery, but Kay suspects it could be when resources are most available since plants store what they produce from photosynthesis during the day as starch, then break that starch and protein down at night to make them available for growth.

“Plants have to coordinate their growth with the availability of resources,” he said. “There’s really no advantage for these plants just to get bigger and bigger if they’re not coordinating their metabolic resources, which come cyclically with photosynthesis each day. So plants grow rhythmically presumably to coordinate growth with available metabolic resources.”

As scientists gain a better understanding of these plant growth control mechanisms, the potential commercial applications to agriculture could be as broad as they are significant. The discovery of the mechanisms of the evening complex should eventually provide plant geneticists with a new way to optimize the growth of crops so they can produce more food or more biomass per acre for biofuel production.

“What this discovery tells us is that the circadian clock is controlling tens of millions of tons of biomass deposition every night in the United States that could be used for bioenergy,” said Kay.

“Now that we understand what the gas and the brakes are in controlling plant growth, we can manipulate those to maximize biomass deposition. We could do it by putting the gas on more or putting the brakes on less or probably in a more sophisticated way by combining the gas and brakes so that we allow the plant to maximize available nutrients, which will allow it to maximize biomass deposition. This could be a way to optimize plant growth for a particular environment where we don’t want to add additional nutrients to the soil.”
Kay said another totally unrelated application for the evening complex could be in making plants, particularly food crops, more tolerant to cold temperatures or freezing.

“When you make mutations to these genes, the plants are less tolerant to freezing and low temperatures,” he said. “So we think the evening complex is likely to have a role in cold tolerance and that’s something else we’re going to be investigating.”

Kansas State University

Corn Growth & Development

In the Corn Belt, including Kansas, corn is an integral component to the success of agriculture. Throughout the growing season, the corn plant undergoes a series of developmental stages as it grows from a seed at planting to a tall plant with an ear at harvest. The following information highlights various stages of growth and development of corn throughout the growing season and various problems during planting and germination.

Planting Conditions

It is important discuss seed placement at planting before we reach plant growth. This photo illustrates placement of the seed after planting. In this particular field, the planter was set at a depth of 2 inches. This was due to this planting date occurring early (early April), which resulted in cool soil temperatures. Planting shallow in this situation places the seed in an area of higher soil temperatures, which will aid in faster germination. Planting corn into a soil temperature ranging from 50 to 55 degrees Fahrenheit may take 18 to 21 days to emerge, while between 60 to 65 degrees Fahrenheit can emerge in 8 to 10 days. Knowing the soil temperature at the planting depth being used is important in understanding when emergence can be expected to occur.

Another factor that is important before seedling emergence is residue management when no-till systems are implemented. Pictured are two rows with varying amounts of soybean residue. The left row has a higher amount of residue covering the row compared with the row on the right. Due to this, the left row has a less uniform stand. This is due to cool soil temperatures as the residue inhibits penetration of heat from the sun. Residue will not only further delay emergence, but can also cause uneven stands, which can also decrease yields. Management of corn or sorghum residue is more critical due to the higher amounts that remain in the field compared to soybeans.

Soil moisture also requires consideration at planting. In this case, this seed was planted when the soil was too wet, which caused crusting. Crusting occurs when water and pressure causes soil particles to “glue” together, creating a layer that is very difficult to penetrate. In this photo, a large clod was removed from the surface, revealing this plant. The yellowness of the plant illustrates its clear deficiency for sunlight. The likelihood of this plant surviving at this point is low. In the event of crusting occurring in the field, rainfall is usually the best method to solving the problem. However, rainfall can also cause crusting to occur if the rainfall intensity is too hard.

Seed Germination

Now that the seed is in the soil, it will begin to absorb water and begin to swell. When enough water has been absorbed and the soil temperature is favorable, germination will occur. The first root called the radicle will then emerge.

The picture illustrates the radicle beginning to elongate, approximately ten days after planting. Soon after emergence of the radicle, the mesocotyl will begin to elongate. The coleoptile, which is a protective sheath over the mesocotyl, is seen first when emergence occurs.

Mesocotyl elongation is very sensitive to soil temperatures. If soil temperatures are too cool, elongation will be slow and emergence will be delayed. Pictured are the developing mesocotyl and coleoptile.

Pictured in this photography are coleoptiles breaking through the soil surface.

Identifying Stages of Growth

From breaking through the soil surface to maturity, the plant will undergo several growth stages. These stages are separated into two groups: vegetative and reproductive. The point that separates these two groups is the appearance of silks. Listed below are both groupings and their respective stages.

VE Emergence R1 Silking
V1 First Leaf R2 Blister
V2 Second Leaf R3 Milk
* R4 Dough
V6 Sixth Leaf R5 Dent
V10 Tenth Leaf R6 Black Layer (Physiological Maturity)
V(n) nth Leaf
VT Tassle

Vegetative Stages


The first stage observed in the vegetative period is known as VE, which is emergence. At this period, the coleoptile is fully visible, yet no leaves are fully developed.


Full development of the first leaf is known as V1.

The number of leaves that are completely developed determine the vegetative stage the plant is at.

Although there are two leaves present on this plant, it is technically not at stage V2. Full development is achieved when the collar of the leaf is fully visible.

The collar is found at the base of the leaf. This will be explained in further detail at a later stage. Another attribute of this stage is the uniqueness of the leaf.

The first leaf on a corn plant has a rounded end, known as the flag leaf. This is the only leaf on the plant that exhibits this trait. When determining the number of leaves on a corn plant, the flag leaf should be the first leaf counted.

This picture illustrates a corn plant with the seed exposed at V1. Located below the seed is the radicle. The area above the seed to below the soil surface is the mesocotyl. At this time, the growing point of the plant is located below the soil surface.


To illustrate V2 and to establish a better understanding of the leaf collar, please examine the following two pictures.

While these two plants look similar, they are not at the same growth stage. The first plant would still be considered V1, while the plant in the second picture is V2. Zooming in will aide in the investigation of the differences.

This photo reveals the collar of the V2 plant from above. After zooming in, the image reveals the collars of the first two leaves. Despite a very large second leaf, on the plant in the first photo, the collar is not fully exposed. However, this plant will reach V2 shortly hereafter, probably within 24 hours.


At this stage, the growing point of the plant are now above the soil surface. Tillers also start to become visible at this stage. Also, leaf senescence, which is the process of degradation and death, begins to occur to the first leaf.


At this stage, many ear shoots, which are the potential ears, are now visible on the plant. Usually, the ear shoots that are located higher on the plant are those that will develop into harvestable ears. Nutrient and dry weight accumulation also increases greatly around this time, which results in greater water and nutrient requirements.

Tassel formation is now starting to become visible at this stage, as shown in the photo to the right.


This stage occurs when the tassel is completely extended and silks are not yet visible. This stage also signifies the amount of vegetative growth that will occur on this plant, as all leaves that will be grown on the plant are now visible. The tassel will usually be visible for 2-3 days prior to the silk emergence, depending on the hybrid and environmental conditions.

Pollen shed will now occur from 2-3 week. The plant is most vulnerable to hail damage at this period due to the tassel being completely exposed and possibly destroyed if hail were to occur.

Reproductive Stages

R1 – Silk

This stage occurs when silks are visible outside the husks. The silks serve the purpose of capturing pollen that falls from the tassel. The captured pollen grain moves down the silk to the ovule, where pollination occurs. This process takes about 24 hours.
Environmental conditions are very important during this growth stage. Stress during this time can cause poor pollination or kernel set. Lack of moisture can cause the silks to become too dry and can greatly limit their ability to transfer pollen.

R2 – Blister

Kernels at this stage are very small and white in color. The fluid that fills the kernels at this stage is usually clear in color. The silks are now beginning to dry and darken to a brownish color. The kernels at this stage are about 85% water and will gradually decline from this point until harvest.

R3 – Milk

Kernels now begin to show a yellowish color on the outside. Also, the inner fluid now has a milky texture, which is caused by accumulating starch. The cob also also gained a considerable amount of size and volume considered to it at R2.

Dry matter accumulation is occurring at a very high rate now. Any stress that occurs during this stage can limit kernel size and weight.

R4 – Dough

The ear now begins to display a brighter yellow in color. Also, the accumulated starch in the kernel begins to thicken from its earlier milky consistency. The cob also begins to develop a reddish color.

R5 – Dent

This stage is easily visible, as kernels are now dented. This occurs as the moisture content of the kernel begins to decrease at a faster pace. At the beginning of this stage, the kernel will be about 55% moisture.

The starch in the kernel continues to evolve from the pasty consistency of the dough stage to a much harder texture. This starch will begin to harden at the top of the kernel and work down towards the cob.

Stress at this stage will only affect kernel weight. An early frost during this period could also have the same effect.

R6 – Physiological Maturity

This stage occurs when the kernel has achieved its peak dry matter accumulation. The hard starch layer has now reached the cob and a black abscission layer, called the black layer, has now formed. This black layer signifies the kernel is finished with its growth for the season. The kernel at the start of this stage is 30-35% moisture, depending on the hybrid and environmental conditions.


The growth rate of a corn plant is slow at the beginning of the season, but increases with the presence of each new leaf. Under non-stressful conditions, the time between new leaves will decrease as the season progresses. The plant is most vulnerable to stress during silking, when important pollination events are occurring.

As the reproductive stages progress, the effect of stress on seed weight will decrease, while the effect on seed number will be minimal after R2. Highest yields will be achieved in areas where environmental conditions are favorable for these growth stages, especially R1. Unfavorable conditions early in the season will limit leaf size, which will decrease photosynthesis, while stress later in the season can affect pollination in the form of kernel size and number.


I swear these pictures are not fake. I grew baby corn in my back yard, and it was easy. All you have to do, to grow baby corn, is fail at growing real corn.

Start by buying a packet of seeds (look for one with a picture of corn on the front). Plant the seeds, either according to directions or just however you want. My four year old put about a dozen seeds in a small pot, and then left it in a corner of the garden where the roots grew through the bottom of the pot and anchored themselves probably miles underground. So you could do that.


Actual gardeners say that corn needs plenty of room and should be fertilized with lots of nitrogen. But who are you going to listen to, real gardeners or a four year old?

We planted ours around Memorial Day, so late May. I noticed the first baby ear of corn yesterday, August first. By that point, it was the size of maybe a large taquito, and had a big tuft of corn silk at the top. (The ear of corn grows in the middle of the stalk, not at the top. Look down.)

If we had planted the corn in a grid pattern, eventually the wind would have blown enough pollen from the tops of the plants to fertilize each strand of corn silk on a neighboring plant. Each strand leads down to a single kernel, and a fertilized kernel grows fat and sweet. If you are bad at growing corn, you may end up with ears that have a mix of plump fertile kernels, and duds. I am not good at growing corn, so I decided to cut my losses.


Right when that first ear puts up its tuft of corn silk, rip it off the plant. Peel open the husk, and there it is: your baby corn. Congratulations, you grew a six foot tall plant just to harvest a four inch ear of baby corn. There’s a metaphor in there somewhere.


Canned baby corn has been boiled and salted, so feel free to do the same. Your homegrown baby corn will taste just like that except fresher. It’s crunchy, aggressively bland before you salt it, and just a tiny bit sweet. Enjoy.

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