Sweet Corn Ears
Corn (maize) is native to America and has been cultivated in Central America since 3500 BC. It was an important food of the Incas, Aztecs, and Mayas of Mexico, as well as the cliff dwellers of the southwestern United States. Iroquois in Pennsylvania and New York grew a variety of sweet corn that turned blue as it matured. Cortés brought corn to Spain, and from there it was quickly introduced into France and Italy. Today, corn is third, following wheat and rice, in world grain production.
Between 2.2 and 2.9 billion pounds of sweet corn are produced annually in the United States. Over the past ten years, national production has fluctuated around 260,000 acres. Acreage in Pennsylvania has declined by about one-quarter during that time to around 16,000 acres annually. Nationally, the sweet corn crop is worth $750-850 million per year. On the basis of value of production, the top five sweet corn states are Florida, California, Washington, New York, and Georgia.
Sweet corn grown in Pennsylvania is usually available from early July to the end of September. Fresh-market sweet corn is traditionally sold from open bulk containers or by the dozen in paper or cellophane bags. Several marketing alternatives are available to the sweet corn grower: wholesale marketing, produce auctions, cooperatives, local retailers, roadside stands, and pick-your own operations. The processing market is only suitable for large, highly mechanized growers. When planning production, first consider your ability to market. You should conduct some market research since growers often overestimate their ability to sell in a given market. Production of less than one acre of many vegetable crops is typical for most growers.
In wholesale marketing, producers often contract with shippers to market and ship the sweet corn for a predetermined price. If you do not use a contractor and choose to ship your corn to a wholesale market yourself, your product will be subject to the greatest price fluctuations. Produce auctions operate weekly; however, you must deliver the sweet corn to the auction. Marketing cooperatives generally use a daily pooled cost and price, which spreads price fluctuations over all participating producers. Local retailers are another possible market, but you must take the time to contact produce managers and provide good-quality sweet corn when stores require it. For more information on marketing, consult Fruit and Vegetable Marketing for Small-Scale and Part-Time Growers.
Retail marketing options, including roadside stands (either your own or another grower's) and pick-your-own operations provide opportunities for you to receive higher than wholesale prices for your sweet corn. You will have additional expenses for advertising, building and maintaining a facility, and providing service to your customers. With pick-your-own operations, you save on harvest costs, but you must be willing to have customers on your farm and accept some waste. Farmer's markets are another retail option, but you should contact the markets well in advance of the marketing season to be sure space is available and to find out what requirements you must follow. For more information about roadside markets, see Developing a Roadside Farm Market.
Sweet corn grows best on well-drained soils that have good water-holding characteristics. If you grow sweet corn on sandy soil, irrigation is important for optimum pollination and kernel development. Soil should have a pH of 5.8-6.6. When growing early sweet corn, use soils that warm quickly and locations with a southern exposure to ensure early growth and harvest.
Sweet Corn Types
Corn is classified as sweet, pop, flour, silage, or feed corn, depending on the type of carbohydrate stored in the ear. Sweet corn gets its name from special genes that prevent or retard the normal conversion of sugar to starch during kernel development. In addition to the various sugar types, sweet corn cultivars differ in kernel color (yellow, white, and bicolor) and maturation times--early (less than 70 days), midseason (70 to 84 days), and late (more than 84 days). Shrunken-2 varieties should be planted at least 500 feet from all other corn types or planted at least two weeks earlier or later than other types since shrunken-2 varieties pollinated by other corn types will produce starchy kernels.
Sweet corn genotypes and sugar content for commercially-available cultivars
|Genotype||Genes present 1||Variety example||Kernels||Isolation 2|
|Normal||su||Silver Queen, Sundance||100% normal||Supersweet, augmented sh2|
|Sugary Enhanced||su, se||Silverado, Silver King, Brilliance||25-100% sugary enhanced||Supersweet, augmented sh2|
|Supersweet||sh2||Snow White, Boreal||100% supersweet||Normal, sugary enhanced (all), synergistic (all)|
|Synergistic||su, se, sh2||Sweet Bread, TripleSweet||0-56% normal, 19-75% sugary enhanced, 25% tender, supersweet||Supersweet, augmented sh2|
|Augmented Shrunken||se, sh2||Gourmet Sweet, Extra-Tender||100% tender supersweet||Normal, sugary enhanced (all), synergistic (all)|
|Mira||su, se, sh2||Mirai 002||100% tender supersweet||none necessary|
1. su = normal sugar types; se = sugar-enhanced cultivars; sh2 = shrunken-2 cultivars.
2. To avoid starchy kernels, isolate by at least 500 feet or at least 12 days in silking. All sweet corn must be isolated from field and popcorn varieties by a distance of at least 500 feet.
Recommended sweet corn cultivars for Pennsylvania
|Yellow||Seneca Horizon (BWMS*)||se|
|Yellow||Incredible (BWR)||su, se|
|Yellow||Super Sweet 7210||sh2|
|White||Quick Silver (BWMS)||su|
|White||Sweet Ice||su, se, sh2|
|White||Super Sweet 8701||sh2|
|White||Avalon||su, se, sh2|
|White||Silver Queen (BWMS)||su|
|Bicolor||Providence||su, se, sh2|
|Bicolor||Synergy||su, se, sh2|
|Bicolor||Twice As Nice||sh2|
Note: All cultivars within a color grouping are listed in order of maturation (early to late).
*BWMS = bacterial wilt moderately susceptible.
Planting and Fertilization
Sweet corn seed generally is planted when soil temperatures reach at least 55°F and the possibility of hard frosts (24°F or lower) has passed in the area. In southern Pennsylvania, try to plant in early to mid-April, and in northern Pennsylvania, in mid- to late May. Depending on cultivar and planting equipment, the optimal plant population is between 14,000 and 24,000 plants per acre. It is recommended that you sow 10 pounds of corn seed per acre 8-12 inches apart and in rows 30-44 inches apart. Leaving space for a drive row will also assist with pesticide application and harvest. Spacing decisions depend on the row spacing of your equipment and the ability to irrigate.
You can produce early sweet corn (ready by July 4) in Pennsylvania by planting short-season varieties and using clear plastic mulch. The mulch can be put down in early spring and the corn planted through the plastic with a special planter, or the corn can be planted in double rows approximately 18 inches apart in furrows, with the plastic placed over the two rows of planted corn. You should put soil along the edges of the double rows to increase the distance between the bottom of the seed furrow and the top of the plastic (ideally 6-8 inches). Remove the plastic from the sweet corn rows when air temperature under the mulch exceeds 90°F for three consecutive days. Sweet corn transplants also can be used to get an early crop, but they are not practical on a large scale (more than an acre). If sweet corn transplants are ready for planting, but field conditions are not favorable, the corn grows too fast and cannot easily be transplanted 12-18 days after emergence.
Fertilizer rates should be based on soil test results and type of sweet corn planted. Banding fertilizer is recommended over broadcast fertilizer applications. Some of the nitrogen should be sidedressed during cultivation if not using plasticulture production methods. The plants should be 24 inches high when sidedressed.
No-Till Sweet Corn
For mid- or late season sweet corn production, no-till planting can be a benefit in relation to time, equipment, and labor. Sweet corn can be planted with a no-till planter in a minimally prepared bed with only secondary tillage, such as an S-tine cultivator, or in a previously tilled field without any tillage treatment, saving both time and labor. Because sweet corn seed germinates and develops when soil temperatures are at least 55°F, early sweet corn production in no-till is difficult because of colder soil temperatures. However, by mid-June, soil temperatures in a no-till field are warm enough for rapid sweet corn seed germination and growth. In addition, no-till reduces soil moisture loss early in the season so more water is available for corn growth later in the season. If you're thinking about no-till sweet corn production, the following factors must be considered in order to be successful: variety, planting date, soil fertility practices, insect pressure and control, planting equipment, cover crop type and stand, and weed species and population in the field.
Weed control can be achieved with a combination of herbicides, cultivation, and a good crop-rotation system. Corn competes well with weeds, but the field should be kept weed free until plants are at least 24 inches tall. Many preemergence and postemergence herbicides are available for sweet corn, depending on the specific weed problem and the corn growth stage. If weed infestation levels are mild, cultivation alone may be sufficient to manage weeds.
Insects can be a major problem in sweet corn production. The corn earworm, corn borer, armyworm, flea beetle, Japanese beetle, and corn rootworm have the potential to cause crop losses. Monitoring insect populations with traps or by scouting will help you determine when you should use pesticides and how often you should spray.
Only a few leaf diseases reduce sweet corn yields. Stewart's wilt, a bacterial disease, is transmitted by flea beetles feeding on young plants within 7-10 days of plant emergence.
Several animals prefer fresh sweet corn to other succulent green tissue and will eat the young seedlings or wait until the young ear of corn is ready to harvest and will help themselves to a sweet corn meal in the field. Deer, groundhogs, raccoons, and red-winged blackbirds can cause serious losses if not controlled. Planting sweet corn in fields surrounded by woods or heavily vegetated hedgerows can increase sweet corn loss caused by these animals. The potential for such losses should be accounted for when you develop your production and marketing plan.
Many of the pesticides required for sweet corn production are restricted-use pesticides and require a pesticide license to purchase. Pesticide applicators tests are usually administered at extension offices, so you should contact your local office for dates and times of these examinations. When using any pesticides in your enterprise, remember to follow all label recommendations regarding application rates and personal protection equipment (PPE) requirements. Also remember that any Worker Protection Standards (WPS) apply to the owner as well as to employees.
Harvest and Storage
Harvesting can be done either mechanically or by hand. New mechanical harvesters usually cost $25,000-30,000, and hand-harvesting costs about $150 per acre. Depending on your labor situation, it is usually not economical to purchase a mechanical harvester unless you have at least 10 acres of sweet corn. Regardless of the harvesting method, you need to check ears for worms, insects, and bird damage to ensure you are marketing a high-quality product.
Immediately after harvest, you should refrigerate and store sweet corn in plastic bags, preferably in the husk, to maintain quality. Sweet corn will retain fairly good ear quality for 2-3 days if stored at 90 percent humidity and 32°F.
All agricultural operations in Pennsylvania, including small-scale and part-time farming enterprises, operate under the Pennsylvania Clean Streams Law. A specific part of this law is the Nutrient Management Act. Portions of the act may or may not pertain to your operation, depending on whether you have livestock on your farm. However, all operations may be a source of surface or groundwater pollution. Because of this possibility, you should contact your local Soil and Water Conservation District to determine what regulations may pertain to your operation.
You may wish to consider several risk-management strategies for your operation. First, you should insure your facilities and equipment. This may be accomplished by consulting your insurance agent or broker. Second, you may wish to insure your sweet corn crop with crop insurance. Third, you may wish to insure the income of your entire farm through a crop insurance program called AGR-Lite.
Crop insurance is a federally subsidized program that is available from private crop insurance agents. The sweet corn policy provides protection against declining income due to damage that causes a yield shortfall. The amount of insurance is based on the cost of growing sweet corn in a specific area and pays when the annual value of the crop is less than the dollar amount of coverage. AGR-Lite is a whole farm policy that covers all your crops and is based on your farm's gross revenue as reported on your federal taxes. To use AGR-Lite you must have five years of Internal Revenue Service (IRS) Schedule F forms. If your business structure is either a C or an S corporation, the necessary information can be entered into a Schedule F for crop insurance purposes.
For more on agricultural business insurance, see Agricultural Business Insurance. For more information concerning crop insurance, contact a crop insurance agent or check the Penn State Extension website.
Included in this publication are three annual budgets: early season fresh market sweet corn using plastic mulch, mid to late season fresh-market sweet corn (hand-harvested), and mid- to late season fresh-market sweet corn using Bt (transgenic) seed for control of ear worms. These budgets utilize custom hire for most of the field work, which could be more economical for smaller acreages. Farmers who have their own equipment should substitute their costs for the custom hire. The budgets summarize the receipts, costs, and net returns for each production option. The sample budgets should help ensure that all costs and receipts are included in your calculations. Costs and returns are often difficult to estimate in budget preparation because they are numerous and variable. Therefore, you should think of these budgets as approximations and make appropriate adjustments in the "Your Estimate" column to reflect your specific production and resource situation. These budgets are developed for one acre; however, your scale of production should be based on market considerations. More information on the use of crop budgets can be found in Enterprise Budget Analysis.
You can make changes to the interactive PDF budget files for this publication by inputting your own prices and quantities in the green outlined cells for any item. The cells outlined in red automatically calculate your revised totals based on the changes you made to the cells outlined in green. You will need to click on and add your own estimated price and quantity information to all of the green outlined cells to complete your customized budget. When you are done, you can print the budget using the green Print Form button at the bottom of the form. You can use the red Clear Form button to clear all the information from your budget when you are finished.
Sample Budget Worksheets
Initial Resource Requirements
Land: less than 10 acres
- Operator: 45-55 hours per year
- Harvesting and packing: 35-40 hours per acre
Capital: $400-600 per year
For More Information
American Vegetable Grower, Centennial Edition. Willoughby, Ohio: Meister Publishing, 2007.
MacNab, A. A., A. F. Sherf, and J. K. Springer. Identifying Diseases of Vegetables. University Park: Penn State College of Agricultural Sciences, 1998. Pennsylvania Commercial Vegetable Guide
Pennsylvania Commercial Vegetable Production Recommendations. University Park: Penn State Extension, 2013.
Pennsylvania Vegetable Growers Association
RR 1, Box 392
Northumberland, PA 17857-9723
Prepared by Michael D. Orzolek, professor emeritus of horticulture; Lynn F. Kime, senior extension associate in agricultural economics; and Jayson K. Harper, professor of agricultural economics.
This publication was developed by the Small-scale and Part-time Farming Project at Penn State with support from the U.S. Department of Agriculture-Extension Service.