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Corn harvesting time


When To Harvest Corn For Perfect Ears

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A delicious summer staple, corn is the backbone of so much of what we eat in the United States. Whether it’s eaten as fresh sweet corn or dried to make cornbread or tortillas, we rely so much on this wonderful plant. But getting the timing right on when to harvest corn can be a little tricky. With its kernels hidden from view, how can we tell when our corn is ready to harvest and time to enjoy the sweet fruits of our labor?

Corn is a grass, believe it or not! When it first germinates in the garden, it shoots up out of the earth with a single little blade of grass-looking matter. Over time it will shoot out more leaves and push upwards, eventually forming nodes and growing ears of corn. Getting the timing right on when to pick corn requires a little planning ahead. 

This crop goes from seed to ear of corn in under 100 days. A common phrase used among people who grow fresh corn in their garden is ‘knee-high by the 4th of July’. That means that the seeds have been planted, germinate and reach about 12-18” high by early July. By no means do you have to follow that rule, but you should take a look at the date of the first frost in your region and count backward to figure out your own planting date. You want to make sure that your corn is ready before a killing frost in the fall undoes all the plants’ hard work. 

Corn on the cob isn’t the only way to eat the bounty of your corn stalks. There is also corn for popcorn, animal feed, flour, cornmeal, and tortillas. Knowing what type of corn you’re trying to grow is crucial to keep your corn sweet when it lands on your plate. 

Unlike when you pick an ear in the home garden, mechanical combines are used to harvest fields of dry corn for animal feed. This is because there are certain types of corn like flint, popcorn, or flour corn that are only picked when they’ve thoroughly dried. This is completely different for sweet corn. 

Sweet corn has a relatively short shelf life. Immediately after harvest, the sweet sugars in the kernels start turning into starches and thus decrease in sweetness. This is why it’s such a popular food to grow with home gardeners. The quality of homegrown sweet corn that’s harvested in the morning from the garden and eaten for lunch is unsurpassed by anything you’ll find on a grocery store shelf, you can taste the sugar in every kernel!

How To Identify If Corn’s Getting Close

Knowing when to harvest corn can be tricky, but it’s worth learning. Source: kanshiketsu

For growers who start their corn in early to late spring, you can expect your corn to be ready for harvest in mid to late summer. Corn takes anywhere from 70-100 days to grow from seed depending on the variety. So, as soon as the chance of frost is gone, and the daily temperature reaches around 65 degrees Fahrenheit, you can go ahead and start planting your corn kernels. 

In order to gauge when to harvest your corn, watch its growth habit. A single corn plant will put out several ears of corn, with the most mature always at the top of the stalk. The corn cobs will start out tiny, and with each passing week swell up in size. Search for the long, semi-transparent white threads called silks that emerge from the top of the ear and sway in the breeze. If you’ve sown your corn close enough, the silks will become pollinated by the pollen from the tassels at the top of the stalks and each kernel of corn attached to each of the silks will plump up and become the kernel of corn you’re accustomed to seeing. 

Be careful not to harvest too soon. If the cobs at the top of the plant are not yet ready, the rest of the cobs aren’t either. Let your corn fully develop in order to get a better flavor. 

Signs of Ripeness

Wait to harvest hard corn types until they’ve dried a while. Source: Pussreboots

Identify The Type of Corn You’re Growing!

There are several different types of corn and they are usually put into different categories based on what they’re used for. What type do you want to grow?

While we have a separate article that goes into depth on the types of corn and how they’re used, let’s do a quick summary:

Sweet Corn (Z. mays var. saccharata or Z. mays var. rugosa): The corn that’s grown for corn on the cob and eaten fresh. Picked while fresh with a milk like substance that oozes from the kernels when ripe; immediately after the silk turns brown. 

Dent Corn (Zea mays var. indentata): The corn that’s used to make homemade corn tortillas. This is also known as field corn and can also be used to feed animals. 

Flint Corn (Z. mays var. indurata): This is sometimes called Indian Corn, it comes in a range of colors and can be used as cornmeal or animal feed. 

Flour Corn (Z. mays var. amylacea): Normally used to make corn flour. 

Popcorn (Z. mays var. everta): The favorite corn of your local movie theater! 

Check For Readiness 

Once your ears plump up, watch the colors of the silks. You need to wait until they turn brown before you can harvest. Once this sign appears, you can test for readiness by gently pulling back some of the husks and pressing your fingernail into one of the kernels. The husks act as a cover for the baby kernels and might be a little difficult to peel back. That’s alright! Give it a good tug and it’ll peel back. If there is still liquid inside the kernel, and it oozes out a milky starch-like substance, it’s ready to harvest. If it oozes a more watery substance, it’s not yet ready. One of the most satisfying tasks in gardening is being able to pick an ear of fresh corn right off the plant. 

There may be some corn cobs that don’t quite plump up all the way. These cobs usually have a few rows of kernels near the top of the cob that haven’t quite filled out. These can be picked anyways, this is a result of under-pollination and at this stage cannot be corrected. 

For hard varieties of corn, you’ll want to wait to pull your corn cobs off until the husk has turned a yellow-brown color and the plants appear to be almost dead. At this point, you’ll want to harvest the entire crop in one go and be able to process the ears fairly quickly. It is essential that the kernels are completely dry or else the kernels can degrade in quality if picked too soon. 

How To Harvest Corn

Sweet corn kernels should be plump and ooze milky liquid when punctured. Source: puamelia

Harvesting corn is one of the easiest things to do in gardening! It’s also one of the most satisfying as well. Once you’re ready to harvest sweet corn, simply take your ear of corn, and bend it downwards and away from the stalk. It should snap right off! Be careful that you don’t damage the stalk, there might be a few more ears ready to pick in a week’s time. Once you’ve pulled a few ears off, you’ll quickly get the hang of it! 

If you’re growing hard corns like popcorn, be sure to leave your ears in the field to dry for 4-6 weeks past when the green disappears from the husks. Gardeners may find it hard to wait, but your patience will be rewarded with a healthier and plumper seed! 

Once your hard corn has dried out, remove the dark husk and with your thumb push against the hardened kernels in order to remove them. With some varieties of corn, you can even rub the cobs against one another to quicken the process. 

How To Store Corn

Corn quickly loses its sugars once it’s been picked. For this reason, try and eat it or process it as soon as it’s been picked. If you can’t get to it right away, you can store it in the refrigerator unwashed for a few days. 

If you’re growing corn to preserve it and enjoy it throughout the year, try to blanch your corn cobs right after picking. Just add the shucked ears to a pot of boiling water and quickly remove it after four minutes of processing. Dunk it into ice water to stop the cooking process and then cut off the kernels with a knife. At this point, you can either freeze it or can it. 

If you’re drying your corn, wait until the husks are dry and papery and the corn kernels are hard to the touch. Pick an ear and test to see if the kernels pop away easily. This is best stored as kernels in glass jars or sealed containers. Dry canning is a great option to preserve freshness! Dry corn is susceptible to insect damage, so bear that in mind when it comes to storage.  

Frequently Asked Questions

Once harvested, your corn is at its best flavor if eaten quickly. Source: naoyafujii

Q: How many times can you harvest corn in a year?

A: In most areas of the US, you can only harvest corn once in the season if your corn is planted all at once. However, if you plant succession crops, starting fresh seeds every week or every few weeks, you can get several harvests in a single year depending on your climate. 

Q: Does corn grow back after you pick it?

A: No. A stalk of corn will put out just a few corn ears. Picking it will not encourage any further ear production.

When to harvest corn: learn how to pick ripe corn every time

(Image credit: Petegar / E+ / Getty Images)

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Knowing exactly when to harvest corn is a great task to add onto your summer gardening to-do list. There's nothing better than throwing some corn on the grill and munching along all summer – and it's particularly delicious when it's fresh from the backyard.

One of the things you might know if you've looked into how to grow sweet corn is that corn matures quickly, taking only a few days to go from unripe to overripe. Luckily, there are lots of ways to check your corn before harvesting, so you know you'll be getting the freshest and most tasty corn. 

Newly picked corn will always taste the freshest

(Image credit: Serban Tunde Irina / EyeEm / Getty Images)

When to harvest corn for the best crops

Whether you're growing it in a raised garden bed or a small vegetable garden, knowing when to harvest corn cobs is all in the appearance.  When it's growing, an ear of corn will be topped by a cluster of silky fibres that need to be pollinated. You'll know it's ripe when these silks have turned brown and begun to shrivel, but the husks are still a pale green color. 

The ear will also start to angle itself away from the stalk – a sure sign of ripeness – and should feel firm and full when you hold it too. 

If you're unsure, you can employ the fingernail trick to check the juice inside the kernels. 'If, when you split a kernel with your thumbnail, juice is thin and milky, the cob is ready to harvest,' says Amateur Gardening's expert John Negus. 'If the liquid is thin and watery, the fruit is not yet ripe.'

How to harvest corn in 4 easy steps

  1. Firmly grasp the ear of corn in one hand.
  2. Hold the stalk with the other hand.
  3. Twist the ear in a gentle motion, down and away from the stalk. 
  4. Strip the husks and silks off the cob so it's clean.

Corn should be picked when the husks are still green

(Image credit: Mike Harrington / DigitalVision / Getty Images)

How long does corn take to grow?

From planting seeds to harvest, most corn crops take between 90 and 120 days to grow. Once the corn silks have begun to appear, it's usually around 3-6 weeks for the cobs to be harvest-ready. 

The RHS mentions that sweetcorn cobs start ripening from the middle of summer onwards. 

Fresh corn should feel firm to the touch 

(Image credit: Inna Chernish / EyeEm / Getty Images)

How to know if corn is unripe or overripe

Because corn ripens so quickly, there's a small window to catch the kernels at their best. 

We recommend relying on the fingernail trick again. If you see a watery liquid, the corn is not yet ripe – so it's best to check again in a couple of days. 

However, once the liquid has turned opaque and seems more like a paste it might be overripe and need to be discarded. 'If it resembles clotted cream, it is past its best and sugars within the kernels have been converted to starch,' explains John Negus. 

You should eat fresh corn as quickly as possible once it's been harvested from your kitchen garden, ideally within a couple of days. It loses its freshness quickly as the sugars begin to convert into starch, and it won't taste particularly good! 

How and when to harvest corn for decorations

Colorful ears of shiny ornamental corn are a hugely popular part of fall decor when decorating your home, both inside and out. To incorporate corn into your fall front porch ideas, you first need to know how to dry and preserve it. 

Instead of harvesting your corn when the husks are still green, wait a while until they're drying out a little and the corn kernels have begun to glaze over. The moisture will have dropped significantly, making these ears of corn easier to preserve. 

Tie a few ears of corn together and hang them somewhere warm so they can dry out completely – this should take around a fortnight. 

You'll know they're totally dry when poking a kernel with a fingernail doesn't make any dent. 

Decorative corn is a perfect addition to your fall decor

(Image credit: J. MacNeill-Traylor / Moment / Getty Images)

Freelance writer and author Flora Baker is a keen amateur gardener and houseplant enthusiast. Her small garden in South London is a constant work in progress as she gets to grips with snail prevention, DIY trellises and what to plant in shady spots overrun with ivy.

When is the best time to harvest corn for grain?

Photo: freeimages.com

Corn kernels

Piotr Schultz, Ph.D. is a free element of agricultural technology. In any corn cultivation system, it must be set with maximum precision. Although in practice this is quite difficult to do. On the one hand, the delay in harvesting is associated with a desirable decrease in grain moisture (Table 1), but on the other hand, weather conditions in autumn contribute to losses due to the development of Fusarium infection (Fig. 1) and respiration of grain saturated with moisture.

In Poland, early and mid-season hybrids reach full maturity in September. Of course, the ripening period depends on the weather conditions of a particular year. In warm years, corn can be harvested as early as mid-September, and in wet and cold years, at the end of the month. In turn, medium-late hybrids ripen, as a rule, in late September - early October. The “signal” of ripeness and readiness of corn for harvesting is the yellowing and drying of the leaves (photo 1), as well as the hardening of the grain.

Photo: Schultz P.

Photo 1. Drying cover leaves of the cob

The new generation of Stay Green hybrids reach full maturity and readiness for harvesting with still green leaves capable of actively photosynthesizing (photo 1). At this time, in many hybrids, a darkening can be seen at the base of the grain, called the "black spot" or "black layer" (photo 2). The base area of ​​the caryopsis darkens as a result of the decay of several layers of cells located there. This leads to the closure of the tubules that provide nutrition, which stops, and from that moment nothing can penetrate inside the caryopsis. The appearance of a black spot is associated with the maximum accumulation of dry matter in the grain; further grain ripening is based on the release of water and, in general, on the death of the entire plant. In the stage of physiological ripeness, the grains on the tops of the ears are the first to enter, and the last are the large grains located at its base.

Under stressful conditions, the grains at the top of the cob reach this phase even faster. This mechanism is triggered by the plant, which limits the formation of small, low-value grains.

Photo: Schultz P.

Photo 2. The “black spot” is visible at the point where the grain is attached to the rod

spots” (Table 1). Earlier harvesting, as well as being late with it, reduces the grain yield. In turn, the water content in the grain is significantly reduced along with the delay in harvesting. About 60 days after the “black spot” phase, the moisture content in the grain begins to increase again (Table 1). Sometimes farms decide to leave corn in the field after reaching the physiological ripeness phase in order to reduce the moisture content of the grain. However, such a step is fraught with a decrease in the quantity and quality of the grain yield (Fig. 2) due to the damage of stems and cobs by intensively developing fungal diseases and pests. When harvesting is late, corn grain loses its quality due to excessive accumulation of mycotoxins in it (Fig. 1).

Table 1. Correne productivity, weight of 1000 grains and humidity during cleaning depending on the terms of cleaning (Sulewska et al. 2006)

900.3 88 296.0 9ATH 25.7
Cleaning period Grain harvest, c/ha mass 1000 grains, g Grain, %
Black Spots 71.1 293.2

38

77.9 304.3 31.0
Through 4 weeks 77.4 307.7 28.5
after 6 weeks 75.3 305.5.5 26.0
Through 8 weeks 70.3 299.7 25.5
after 10 weeks 66. 4

Different types of hybrids mature differently

There are significant differences between maize hybrid types in terms of maturation mechanism and potential yield increase. Types flint and dent behave differently. To get the maximum yield and at the same time low costs for drying grain, when determining the harvesting time, the type of hybrid must be taken into account.

flint type. As the grain matures in successive stages, the front side of the grain remains hard, reducing water throughput (photo 3). As a result, the plant is forced to transport assimilates into the grain, overcoming a strengthening barrier on the outside. From a practical point of view, this situation means that in autumn the increase in the yield of hybrids of this type slows down simultaneously with the degree of grain ripening. In principle, from the moment the grain moisture reaches 35%, the increase in starch and dry matter in such hybrids decreases. Therefore, flint-type hybrids are more suitable for earlier harvesting dates.

Photo: Schulz P.

Photo 3. Grain of flint type hybrid

dent type . In such hybrids, water loss occurs along with subsequent maturation phases. This is due to the throughput of the grain walls. In such hybrids, the side edges of the grain become hard and less water permeable, while the front side remains tender, soft and highly permeable to moisture (photo 4). The process of constant return of water begins with low air humidity and open dry leaves covering the cob. Between the juices of the plant and relatively dry air, a difference in water content arises, which forces the plant to level it by transpiration or water release. This serves as a signal to agronomists that the process of starch formation continues and due to this, one can count on an increase in grain yield.

Photo: Schultz P.

Photo 4. Dent type grain

In favorable weather, the moisture content of the grain, which was 30% in the phase of physiological ripeness, can even drop to 20% by harvest. Each day of delay in harvesting contributes to drying and reduces the final moisture content of the grain. During sunny and windy weather, a grain of corn reduces humidity at a rate of about 1% per day. This happens from the second half to the end of September. In the first half of October, the rate of water return is 5%, and in the second half of the month and in the first half of November - almost 0.2-0.3%. Later, the water content in the grain even increases (Table 1).

Photo: realagriculture.com

Harvesting corn for grain

Conclusions

  1. The optimal time for harvesting corn for grain falls on 2 weeks after reaching physiological ripeness - the "black spot" stage. Earlier dates, as well as delays in harvesting, reduce the grain yield.
  2. Keeping corn in the field after reaching the stage of physiological ripeness in order to reduce grain moisture leads to negative consequences: a decrease in the quantity and quality of the crop due to the development of fungal diseases and pests.
  3. There is a significant difference between the types of corn hybrids in the process of maturation and obtaining a potential increase in grain yield.

Translation from Polish: Anna Kislekova.

Prepared based on materials published in the journal Our Agriculture (2013, No. 17).

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Optimum harvesting times for silage corn

To get the most energy from ensiled corn, optimal mowing times must be observed. At the same time, the timing is not based on the date, but on the actual maturity of the crop.

Target:

  1. Good ensilability and low risk of reheating for high aerobic stability;
  2. High percentage of fully mature starch in the grain;
  3. High digestibility of stems and leaves;
  4. Ripening without damage by Fusarium and the formation of fungal poison.

Optimum grain maturity

The best time for harvesting corn for silage is the end of the milky ripeness phase, when 2/3 of the grain reaches this stage. You can appreciate this by cutting the grain with a sharp knife. Corn can ripen very quickly. Each grain in the combine must be "broken" into three parts. Check if this is the case every hour. As the plant matures, the nutritional value of the stems and leaves decreases, but most importantly, the overall nutritional value of the plant increases as the grain ripens: milky, waxy and grain maturity stage - the accumulation of a large amount of starch.

Optimum plant moisture Harvesting at humidity above 70% will lead to a decrease in energy levels, part of the nutrients (starch, sugar) will be lost along with the juice, which will lead to the creation of optimal conditions for the life of Clostridia. Clostridia, in turn, process sugars and organic acids into butyric acid, carbon dioxide and ammonia. The resulting silage will have a high butyric acid level, an unpleasant odour, a high pH, ​​and a low dry matter content.

High % DM. Low moisture silage is harder to compact, making it difficult to remove capillary air tubes and reduce the oxygen content of the silage. The fermentation processes worsen, the feed warms up. Corn silage with a high dry matter content has a lower digestibility of starch and fiber. Too dry grains transit through the cow's digestive system.

Optimum whole plant moisture content 65% . Maize reaches ripeness at the moment when the accumulation of starch in it is completed, and the dry matter content in the grain is approximately 60%, in the ears themselves about 55%, and in the whole plant 30-35% (during wax ripeness). If the corn plant is normally developed, then the part of the ears will be more than 50%. In this phase, with optimal nutritional value and silage, the best amount of nutrients is achieved.

Nuances

  • Harvesting time may shift depending on the number of cobs, the more there are, the more the harvesting time is transferred to the end of the wax ripeness phase, but it is necessary to take into account the available technical possibilities for crushing the grain.
  • Harvesting too early results in 1.5-2% less ME (metabolic energy) per week. Therefore, when growing this crop, it is necessary to take into account, in addition to temperature conditions and place in the crop rotation, the type of ripening of leaves and stems, ripeness in general, so that the maximum ripeness of the product is reached by the time of harvesting (usually several varieties are selected for phased ripening).

Important: Please note that corn is very susceptible to freezing temperatures. During the period of wax ripeness, it can withstand frost down to -4, frozen corn must be removed within three, maximum five days, because at positive temperatures the raw material will quickly be affected by bacteria, the plant will begin to rot and break, which is fraught with large economic losses.

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