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Planting, Growing, and Harvesting Sweet Corn
Planting
The most common reasons for slow growth include poor light levels, not enough moisture, or a lack of nutrients. Plant in full sun (at least 6 to 8 hours of direct sunlight). Soil needs to be consistently moist (though well-draining),as corn tends to suck up a lot of water. Corn is a hungry plant, so it’s important to enrich beds with lots of organic matter, such as garden compost (ideally in the fall).
When to Plant Corn
- Most gardeners sow corn directly in the garden soil (versus indoors) so that their sensitive roots aren’t disturbed when transplanting.
- Corn is very sensitive to frost; do not plant soil temperature is at least 60°F (16°C), or 65°F (18°C) for super-sweet varieties. Usually, this is 2 or 3 weeks after the last frost in spring. See our Planting Calendar for corn based on average frost dates.
- If you live in an area with a shorter growing season, choose an early variety that will mature well before the first fall frost. The ground can be warmed by a black plastic cover; sow seeds through holes in the plastic.
- A couple of weeks after planting your first round of corn, plant another round in order to extend the harvest.
How to Plant Corn
- To speed germination, moisten seeds, wrap them in moist paper towels, and store them in a plastic bag for 24 hours.
- Because corn is wind-pollinated, it’s essential to plant in a block, rather than a single row. For decent pollination, we recommend a modest block of, say, 10 to 50 plants. This maximizes the chances of the pollen released from the male tassels at the top of the plants drifting down into contact with the female silks lower down. Incomplete or inconsistent kernel development, with the cobs only partly or sporadically filled, is down to poor pollination. The silks protruding from the end of each cob are responsible for carrying the pollen down to the kernels. One strand connects to one kernel, so for complete fill, every strand of the silk must be pollinated.
- Sow seeds about 1½ to 2 inches deep and 12 inches apart in rows 2½ to 3 feet apart. Don’t plant too close together or you run the risk of disappointingly small cobs.
- You may choose to fertilize at planting time with a general purpose (10-10-10 fertilizer); corn is meant to grow rapidly.
- Water well at planting time.
Sowing Corn Indoors
If you’re going to start seeds early, sow the seeds in pots under the protection of a greenhouse, hoop house, or cold frame. This means you can begin sowing three to four weeks before your last frost date, giving you a head start on corn sown outdoors—a huge advantage for areas with shorter growing seasons.
Sow eight to ten seeds half an inch deep into four-inch-wide pots, or sow two seeds per module in a plug tray and remove the weakest of the two seedlings when they emerge. Keep the potting soil moist as they grow on.
Harden off the plants as your recommended planting time approaches by placing them outside for increasingly longer spells over the course of about a week. Plants should be at least six inches tall by the time they’re transplanted outdoors.
Check out this video for great tips on growing juicy corn:
Types
Types of Sweet Corn
There are four main types of hybrid sweet corn: sugary (su), sugar-enhanced (se), shrunken (sh, sh2), and synergistic (sy). Each one contains a different level of sucrose, changing the flavor and texture of the corn.The type of corn will be listed right on the seed packet.
It’s important to be aware of which type of corn you’re growing—not only because of the sugar content, but also due to how easily the types can cross-pollinate. If the wrong combination of types cross-pollinates, the ears that are produced may be of subpar quality.
- Sugary (su) sweet corn is the classic sweet corn. Sugary varieties grow vigorously and are stress resistant. The kernels aren’t too sweet and are said to have a “traditional” taste. However, the sugars in sugary sweet corn quickly turn to starch after the ears are picked, so they need to be eaten right after picking. Do not plant near shrunken or synergistic types.
- Sugar-enhanced (se) sweet corn is slightly sweeter than sugary varieties. They keep their sweetness for a longer period of time after harvest (a few days) than sugary varieties. They grow well with few issues. Do not plant near shrunken types.
- Shrunken (sh, sh2) sweet corn—also called “supersweet”—are the sweetest varieties, containing two to three times more sugar than sugary varieties. The sugar in their kernels lasts even longer after harvest (up to a week) than the other types, but kernels tend to be more crunchy and not taste as “corny.” Shrunken types are also more finicky overall. Do not plant them near any other types; hybrid kernels turn out starchy and tough.
- Synergistic (sy) sweet corn combines sugar-enhanced with one of the other two types to create varieties that have the best of both worlds. Synergistic types tend to have very sweet, tender kernels with a good taste and some synergistic varieties can keep up to a week after harvest. Do not plant near sugary or shrunken types.
Recommended varieties include:
- ‘AԳ’: sugar-enhanced variety, good taste. White kernels.
- ҵdz’: midseason, normal-sugar variety. Yellow kernels.
- ‘Luther Hill’: dwarf, normal-sugar variety. Produces 4- to 6-inch ears on 4- to 5-foot stalks. White kernels. Grow at least nine dwarf plants in a block of three or four rows.
- ‘Silver Queen’: normal-sugar variety. Resistant to some bacterial diseases. White kernels.
- ‘Sweet Sunshine’: supersweet variety. Disease resistant and high yield. Yellow kernels.
Corn can be a feast for the eyes, too! Look for these ornamental varieties:
- ‘Glass Gem’: Sporting multi-colored, semi-transparent kernels, this is a favorite for kids.
- ‘Painted Mountain’: Looking for the classic “maize” colors? This variety has a great diversity of natural tones.
Harvesting
- The warmer the air, the more quickly corn matures. It is usually ripe about 15 to 23 days after silking and sooner if temperatures are exceptionally high.
- When two ears grow on a stalk, the upper ear matures 1 to 2 days before the lower one.
- At harvest, ears should be rounded or blunt, not pointed, with tassels turning brown and kernels full and milky.
- To test, pull down some husk and pierce a kernel with a fingernail. If it’s white, or milky, it’s ready. The milk stage is brief; in hot weather (over 85°F/29°C), sweet corn is at peak for only 1 to 2 days, so check it frequently. Corn harvested a few days after milk stage will not be as sweet.
- Pull ears downward and twist to remove from stalk.
- Sweet corn varieties (except for supersweet varieties) lose their sweetness soon after harvest. Immediately after picking, prepare the ears for eating or preservation.
- Prepare for eating or preserving immediately after picking. Enjoy your harvested corncobs as soon as you can. The quicker they’re cooked, the sweeter they will be!
- If immature corn suffers a late-season frost, the plants and cobs can be damaged and result in the death of the plant or poor-tasting corn.
How to Store Corn
- Sweet corn freezes well, especially if removed from ears before freezing. Learn how to properly freeze corn.
- Corn can also be harvested for other purposes!
Cooking Notes
- If too much hot pepper or spice has been added to a soup or stew, adding a can of sweet corn can help.
- Popcorn is also a favorite snack if you have leftover kernels. Learn how to make homemade popcorn here.
Catherine Boeckmann
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What day should I plant corn on the ground I have already started it in pots in doors
Please see planting guidelines above. To plant corn directly outdoors, select a time about 2 weeks after your last expected spring frost date. To find this information, you can go to the following link and put in your zip code:
/gardening/frostdates
Another way is to use our Gardening Calendar page — input your zip code, and it will tell you dates to plant various crops both indoors and out, including corn.
/gardening/planting-dates/
Hope this helps!
I roll up clean panty hose and cut in four sections. Then I use the long strips to tie down the tomato plants. It does not cut the plant, but stretches, and the tomato grows to where it is stretched to.
I also use the home made compost layered in a fifty gallon plastic can. Raise up at least six inches off the ground. Add leaves,, grass clippings, chicken poop, coffee grounds, egg shells, bananas, and small branches for air space, repeat. You leave in sun. Add one gallon of water. Drill hole at bottom and put in rubber wine cork. After a few weeks of cooking. Pour another gallon of water on. Pull cork and drain juice into bucket. You now have compost tea. Put cork back in. Then keep adding to the bucket. It shrinks down every few weeks. You keep taking juice. You don't have to stir or break your back mixing. I also use the 10-10-10 every 10 days. I am in Sacramento. I get two to 3 pound tomato.
How do u apply the pantyhose to tomato plant. Would u mind being a little more descriptive on those steps. I like the idea
Strips of pantyhose make great garden ties for plants that need to be secured to a stake or cage. One way is to cut strips (each about 1 inch wide) across a pantyhose leg. You should then have a circle of material—you can then stretch each loop a bit and then cut it, so that you have one long strip. Use a strip to tie a branch of a tomato, for example, to a stake to give it support. Make sure that your loop of hose around stem and stake allows wiggle room (say, the width of two fingers) to avoid injury to the plant stem and so that air circulates around the stem.
I will be planting some onion plants in the garden soon. How far ahead of planting can I till in some triple 12 fertilizer and still reap the benefits of the fertilizer?
Hi Darwin,
If you use a quick-release fertilizer wait about two to three weeks before planting. If you use a slow-release fertilizer you can wait longer.
March 17, 2016. Warrandyte, Victoria, Australia. Have just today harvested my backyard garden and my corn is beautiful, the kernels are full and juicy and so flavoursome. Freshly cooked and smothered with butter, yum.
Good on ya, Wayne! Are you having us on for tucker?! Make room for ten and we’ll bring the tatties! You’re killing us here, where snow’s forecast for Sunday–Monday. We’re all “ears” to hear your season’s off and running!
My husband and i bought some walmart seeds about 3 weeks ago. We hand tilled and mixed in compost/manure into native soil (southwest texas by rio grand river). We planted per instructions on package, 3 seeds per hole at 13in apart. We have 4 rows of 5 holes. Seedlings todat are about 2-1/2in tall now and I wanted to know how do i thin and how do i know which seedlings are the ones to keep? Any info greatly appreciated!
