How to Grow Sweet Corn
Sweet corn is sweeter than field corn due to a “sugary (su) gene”; sugary enhanced (se) and supersweet (sh2) varieties are also available, and to make the deal even sweeter, there are varieties with a combination of two and even three of the sugary genes; synergistic (sy) and augmented supersweet (shA). Depending on your sweet tooth, you have some options for sweetness level.
Planting
When planting sweet corn, it should be planted in a block formation rather than a single, long row to allow for the plants to be closer together for adequate pollination. Without pollination, corn kernels will not develop on the ear. The recommended spacing for planting sweet corn is 8 to 12 inches apart in rows 2.5 to 3 feet apart, with seeds being planted about 1 to 2 inches deep. Sweet corn does not tolerate cooler temperatures, so it is best to wait until soil temperatures have reached at least 60 F at a 2-inch depth.
Corn is a nitrogen-loving plant, so it is important to apply nitrogen for healthy growth. Ideally, it is best to apply nitrogen in split applications. A general-purpose fertilizer (10-10-10) pre-plant application can be applied at 25 lbs per 1000 sq ft. Side-dress recommendations vary and can be custom-fitted to growing conditions. It is best to get the young plants off to a good start, so an additional nitrogen application is recommended when the plants are 6 to 12” tall; apply 1 to 2 lbs of actual nitrogen per 100 feet of row. Spread fertilizer between the rows or on either side of a single row and lightly incorporate it into the soil. It is recommended to make 2 to 3 side-dress applications throughout the growing season.
Sweet corn requires about 1 inch of water per week. Heat and moisture stress during pollination and grain fill can result in poor kernel set, so it is important to make sure plants get enough water during this time. During pollination, drip irrigation or soaker hoses are the best methods for providing additional moisture.
It is important to always start with a clean, weed-free planting area. Once the corn is planted, light, shallow tillage can be done to control weeds between rows; however, avoid getting too close to the root system of the plants. Mulching with grass clippings, straw, etc., can also be used to keep weeds down. Herbicides are also an option, but be sure to read your label for proper application.
Insects
Corn earworm, European corn borer, corn rootworm, and Japanese beetles are the most common insect pests of sweet corn in the Midwest. Some sweet corn varieties have the (Bacillus thuringiensis) protein to help protect against corn earworm and European corn borer. For varieties without the trait, Bt is also available as an insecticide spray for high insect pressure. Corn rootworm beetles and Japanese beetles can cause issues with pollination as they often feed on the corn silks. Other problematic insects of sweet corn include fall and common armyworm, corn flea beetle, black cutworm, and corn leaf aphid. It is always best to scout the crop periodically to check for the presence of insects and insect damage. Control is not necessarily warranted unless damage or insect numbers have reached a threshold. Threshold information for sweet corn insects can be found in Purdue Extension's Sweet Corn Pest Identification and Management guide.
Diseases
The diseases we see most often in sweet corn are Gray Leaf Spot (GLS) and Northern Corn Leaf Blight (NCLB). These two diseases overwinter on crop residue, which is why we often see it every year. Crop rotation, tillage, and resistant varieties are the best management practices for these diseases. Common smut is often seen when plant tissue is wounded by hail, wind, or mechanical damage. Conditions that negatively affect pollination can also lead to the presence of smut. Anthracnose leaf blight and stalk rot, as well as crazy top and common rust, are often seen in wet years as these diseases favor a moist environment. Southern rust can also be an issue in sweet corn; however, it is only an issue when the pathogen is blown in from the south, and we have a hot, humid environment. Most of these diseases can be controlled through the use of resistant hybrids (if available), burial of crop residue, crop rotation, or application of fungicide. The Sweet Corn Pest Identification and Management guide is again a useful resource in identifying diseases and figuring out how to best manage them.
Additional Pests
In addition to insects and disease issues, it is also common to face problems with vertebrate pests such as birds, raccoons, and deer. These can be a bit more difficult to control. The most common method of control includes an electric fence to keep raccoons and deer out. To keep bird damage to a minimum, it is suggested to select varieties with tight husks or good tip cover. Typically, the earliest and latest ripening fields are subject to the greatest damage, so try to plant at a similar time as neighbors. Repellents can be used for smaller home garden plantings but can be costly on a larger area basis. Repellents are most effective when coupled with other tactics, such as electric fences, to deter wildlife. Consult local wildlife professionals for more questions.
Harvesting
Sweet corn can take 60 to 100 days to mature, depending on the variety. By making successive 2-week plantings, sweet corn can be enjoyed for a longer period of time. Sweet corn should be harvested at the “milk stage,” which is when the kernels are fully formed but not completely mature. Once the silks dry out, start checking the firmness of the ear and the fullness of the tip kernels. Check frequently to make sure the ears do not become too mature. After picking, it is best to eat, can, or freeze the corn sooner rather than later before the sugars decrease and starch content increases.
Originally published by Katie Parker, May 15, 2020.
Fertilizing Sweet Corn
Growing sweet corn is different from growing field corn. Many farmers tell tales of failure while trying to grow corn, especially the sweet corn variety. Yet, it is so popular in American homes and backyard barbeques.
We definitely have tales of success and failures with corn. So, we would like to share with you the methods that work for us! This starts with soil health.
We recommend fertilizing sweet corn to give your crops the best start. Read on to find out how to use nitrogen fertilizers after you plant your corn patch.
Growing Corn
Each year we expand our garden and experiment with different gardening methods and types of plants. We find great joy in producing food for our family.
And we find even greater joy when sharing our home-grown foods with friends and neighbors. And share the results of our gardening experiments with you.
Some musts we have come to rely on are our large-scale composting on the farm, vermicomposting to enrich the soil, and our automatic drip irrigation system, which works perfectly with our DIY raised corner garden beds.
Some gardeners forget that starting with the best soil for raised garden beds means taking the time to test the soil before planting to provide any necessary amendments to the soil for optimal growth.
Sweet corn varieties, especially the sugary enhanced corn, are definitely among the crops that do best with healthy soil, particularly soil high in nitrogen content. After learning how to plant corn in healthy soil, adding nitrogen to the soil during the early days of growth is beneficial.
Following this practice of adding nitrogen to the soil will result in full ears of corn and a hearty crop perfect for sharing with friends and family.
Fertilizers Used for Sweet Corn
Applying fertilizer when growing sweet corn helps maintain plant health so that you can harvest full ears of corn with juicy, sweet kernels.
General Fertilizer – Adding a general fertilizer (10-10-10) to your soil in the fall to winter over is a good practice. If you didn’t add fertilizer in the fall, you can still add it in the spring when you are preparing your corn patch.
Organic Matter – Compost, manure, and mulch offer nutrients to the soil and help keep the soil moist and aerated. Add in the fall and the spring.
pH Amendments – If you test your soil in the fall and find that it is outside the recommended pH level for corn (6.0 to 7.0), then adding lime to the soil before winter hits will help neutralize the acidity in the soil.
Nitrogen Fertilizer – Corn is a heavy nitrogen feeder. It will use up all the nitrogen in the soil in one growing season. Use a side dressing of straight nitrogen fertilizer, ammonium sulfate, at least once per growing season. Use a 21-0-0 to a 34-0-0 ammonium sulfate fertilizer.
The Best Time for Fertilizing Sweet Corn
In the Fall – The best time for fertilizing sweet corn starts with the soil preparations in the Fall. Adding a general fertilizer to the soil works well, like a 10-10-10 fertilizer. Take a soil test to ensure the soil’s pH level falls between 6.0 and 7.0. Add lime if the soil is too acidic.
Before Planting – Make any necessary amendments to your soil. We like using the compost from our farm or our vermicomposting to add nutrients to the soil. Work in organic matter or fertilizers to the soil at least a few inches deep before planting your corn seeds.
Early Growth – Then, once the corn begins to grow and measures about 12 inches high, add straight nitrogen fertilizer. It is important to add nitrogen when the corn is small but growing at its fastest rate.
How Often to Fertilize Sweet Corn
You can side-dress your sweet corn with nitrogen 2 to 3 times in the growing season. If you have particularly sandy soil or it happens to have a lot of rain, you may even want to side-dress more frequently.
Without adding nitrogen fertilizer, your corn stalks may become dry and crinkly. You may experience poor kernel development or have very few ears of corn on each stalk.
Can You Use Too Much Fertilizer on Corn?
Be sure to follow the recommendations of the fertilizer you decide to use. Adding too much nitrogen fertilizer can cause problems, too. Too much nitrogen can cause corn stalks to fall over or increase the possibility of disease.
There is only so much nitrogen corn plants will take in, so if you over-fertilize, the fertilizer just becomes run-off and can enter the water stream. That is why we highly recommend testing your soil so that you are not guessing.
Supplies Needed
Fertilizer – Use an ammonium sulfate fertilizer, at least a 21-0-0 nitrogen fertilizer.
Tiller – We use a Troy Bilt tiller that fits between our corn rows.
Water – Plan to water your corn after fertilizing. Your corn plants should receive about an inch of water a week.
Fertilizing Sweet Corn Step by Step
Purchase a nitrogen fertilizer. This can be an ammonium sulfate with 21-0-0, meaning 21%nitrogen. You can use fertilizers with a higher percentage of nitrogen as well. 21-0-0 would be the minimum recommendation.
Once your corn plants are about 12 inches tall, side-dress the corn by sprinkling the fertilizer around the base of each corn plant.
Use a tiller that fits between the corn rows to till between each cornrow. This will work the fertilizer into the ground, helping the nitrogen reach the root systems quicker. It also helps control weeds, and it aerates the soil.
Water your corn patch.
Watch your corn grow healthy and strong over 60 to 100 days, and be ready to harvest delicious sweet corn!
We hope you decide to grow sweet corn and wish you great success on your harvest! We find raising and growing our own food so rewarding. And we love sharing our story with you. Check out our posts on raising chickens, roasting a whole hog, extracting honey, and butchering quail. Whatever farming endeavor you want to try, we encourage you to give it a go!
How To Fertilize Sweet Corn – The Simple Secret To Growing Great Sweet Corn!
Did you know that one of the most important things you can do for your sweet corn crop is to fertilize it. In fact, not only will it help grow healthier, larger stocks and a bigger harvest of corn, but it can also help the ears of your corn to be fuller and tastier as well!
There is simply nothing better than enjoying the incredible taste of fresh sweet corn in the summer. Especially when it’s fresh-picked from your own garden.
But there are a few secrets to growing a successful crop of tasty sweet corn. And one of the biggest secrets of all is making sure your corn has the nutrients it needs to develop and flourish – and that is exactly where fertilizing comes into play!
Sweet corn requires a lot of energy and nutrients from the soil. Not just to sprout and grow healthily, but to produce fully developed and flavorful ears of corn.
Sweet corn takes a fair amount of nutrients from the soil as it grows and matures. And without additional supplements throughout a season, it can easily run out of steam. Especially if it happens to be growing in garden soil that had corn or other heavy feeding vegetables planted in it the previous year.
But fertilizing corn is different than fertilizing most vegetable crops. Sweet corn’s nutrient needs actually vary based on where it is in its growth cycle. And to really grow great sweet corn, you need to fertilize it in the right way, and at just the right time.
How To Fertilize Sweet Corn – The Secret To Growing Great Sweet Corn!
Sweet corn benefits immensely from 3 simple and timely fertilizing applications. The first is at planting time. This dose, as you will see below, is different than the final two. It is an extremely light feeding that helps seeds to establish quickly without burning them out.
The second fertilizer application should come as the corn reaches around 4 weeks of age. This dose, as with the final application (at 8 to 10 weeks) needs to be more powerful to allow the plant to produce big stalks and full ears.
With growing great sweet corn in mind, here is an in-depth look at each stage of fertilizing, along with the best choices for providing the right nutrients at the right time.
Getting corn off to a fast start is critical to a good harvest. With warm soil and the right dose of fertilizer, corn seedlings will develop quickly.
Fertilizing Seedlings – How To Fertilize Sweet Corn
Corn seedlings require a lighter, more balanced dose of fertilizer. This helps the plant to develop good roots, stems and foliage. All of which are extremely important in setting the stage for ears to form within the husks.
At this early stage, too much power from too strong of a fertilizer will cause more harm than good. Not only can it stunt early growth, but it can even kill it off with too “hot” of a dose of fertilizer.
One of the best choices of all to fertilize young seedlings is to use an all purpose granular fertilizer that has a lower percentage of nitrogen, phosphorous and potassium. Affiliate Link: All Purpose Granular 5-5-5 Fertilizer
This will keep from overpowering young seedlings but still get them off to a fast start. A light sprinkling over the surface of the soil around plants is more than enough to do the trick. As the granules break down, they will leach down nutrients to help young seedlings take off.
Fertilizing At 4+ Weeks – How To Fertilize Sweet Corn
The second and third applications of fertilizer for sweet corn are by far the most important. It is at this stage when the roots of the crop are trying to absorb as much power as possible. And when it comes to developing sweet corn, the most important nutrient for this stage is nitrogen.
Nitrogen can quickly be depleted from the soil by a crop of corn. And resupplying it can be a critical part of the corn growing to full maturity. Unlike many fruiting vegetables and flowers that need more phosphorous and potassium to set blooms and fruit, corn needs nitrogen.
It’s not that phosphorus and potassium don’t matter for corn, but not nearly at the same level as nitrogen. The duo of phosphorous and potassium do help aid in strong root and stalk development – in fact, in this case, more potassium than phosphorous is ideal as well. But make no mistake, it is nitrogen that matters most.
There are a whole host of fertilizers on the market for corn and vegetables. The key for sweet corn is to look for one that has an N-P-K ratio that has a higher nitrogen rating. It’s also good to find one that provides more potassium as well – and at least a trace amount of phosphorous.
The Final 2 Doses Of Fertilizer – When & How To Fertilize Sweet Corn
Once your seedlings have been growing for four weeks, it’s time to apply the fertilizer. By four weeks, the corn crop has become established in the soil and can handle its first stronger supplement of nutrients. You will want to apply the first feeding at 4 weeks – and another at 8 weeks. You can use either a liquid fertilizer or a granular one for this as both work well.
Liquid fertilizers work fast for corn, giving your stalks the energy they need quickly.
Using Granular Fertilizer
How you apply the fertilizer is important. If you are using a granular fertilizer, the best way to apply it is by using a side dressing technique. Spread the fertilizer into the soil about 3 inches to each side of the main stalk down the row.
This allows the crop to absorb the nutrients down at the root level, and keeps the foliage from being damaged from the fertilizer. Granular fertilizer left on the foliage or at the base can be too hot and burn the plant quite easily.
As for how much to apply, a good rule of thumb is about 1/8 of a cup for every two to three corn plants. Many times, rates of application are given in pounds per square foot, but for a home garden, that can be hard to relate. The cup ratio works well and is much easier to use in practical terms.
Using Liquid Fertilizer – When & How To Fertilize Sweet Corn
If using a liquid fertilizer such as the one recommended above, simply mix according to instructions with water and apply to the soil around your plants. Liquid is a far faster acting fertilizer and can supply the sweet corn with the nutrients it needs faster – but both liquid or granular fertilizers will do the trick.
The biggest key of all is making sure to fertilize! Here is to powering your sweet corn this year and to growing your best crop ever. For more on fertilizing vegetables, check out our article on powering your cucumber plants: Fertilizing Cucumbers – How To Power Your Plants To A Big Harvest!
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