Tips on Growing Sweet Corn

Roasted and slathered in butter and herbs, nothing says summer more than sweet corn on the cob. Because corn is in the Gramineae family which includes grains and grasses, there are a few cultural practices to keep in mind when planting this crop.

 

Planting Sweet Corn: Corn needs full sun and good fertile soil.  It is a heavy feeder especially of nitrogen.  It has relatively shallow roots for a tall plant so it is sensitive to moisture fluctuations.  Since corn is wind pollinated it needs special consideration when spacing the plantings. Corn needs to be planted in blocks or 2 rows double planted to ensure good pollination and ear development.  It can be planted 2 weeks after the last frost of your area when soil temperatures reach 60 degrees.  A second and third planting can be made on Mother's Day and Memorial Day.  Always direct seed corn into the garden.



Jubilee sweet corn



Silver Queen sweet corn

Varieties of Sweet Corn

Hybrid sweet corn is planted most by the home gardener. Most people love the high sugar content of these corns. On the seed packet or in the seed catalogs sweet corns are one of 4 types SU standard sugary, SE sugary enhanced, synergistic and SH2 super sweet corn.  There are differences in these corns and choosing what will grow in your planting will result in success. 

SU Standard Sugary:  

• Has an average level of sugar (8% to 18%) that becomes starch quickly after harvest.
• Both hybrid and open-pollinated types are available.
• It is the traditional type of sweet corn.
• Some describe sugary corn as having “old-fashioned” flavor.
• Its kernels are tender and creamy. They can taste chewy as the sugar becomes starch.
• It is important that you pick these varieties the same day that you plan to eat them.
• Gardeners who want to freeze or can corn prefer this type, as the flavorful, creamy kernels hold up to processing.  
• Isolate from Shrunken (sh) and Synergistic (sy) types.

Varieties: 

My favorite is Silver Queen with its white kernels, two to three ears on 7 ft stalks. Jubilee is a yellow corn with 2 ears on 7 ft stalks. Both are good fresh eating and freezing varieties.  These two varieties have proven productive and reliable in my garden They need 80- 92 days to mature and you need to stagger the planting so they don't cross pollinate.

SE Sugary Enhanced:  

• Sugary enhanced has an increased sugar level (30% to 35%), and the kernels are tenderer.
• The sugar is slower to become starch after harvest.
• Fully Sugary Enhanced (se+) types are even sweeter. They will still be sweet after three or more days in the refrigerator.
• Isolate from Shrunken (sh).

Varieties:  Bodacious, Kandy Corn, Delectable, Sugar Buns

SH2 Super Sweet Corn or Shrunken:  

• Also known as "Supersweet."
• Shrunken have two to three times the amount of sugar (40% to 50%) compared to Sugary varieties.
• They have a crispy texture.
• They can keep their sweetness for a week in the refrigerator.
• Some people find shrunken corn lacking in “corn” flavor, and they are less creamy.
• Seeds are smaller and lighter in weight, and look shrunken when dry.
• Isolate from all other sweet corn types.
• Cross-pollination between Shrunken (sh) and any other types will result in starchy, tough kernels.

Varieties:  Super Sweet Jubilee, Honey n Pearl, How Sweet It Is

Synergistic:  

• They have a combination of sweetness genes.
• All have at least one (se) gene.
• They may be combinations with (sh) or (su), or both.
• These varieties are very sweet, crisp, tender and creamy.
• Some also have longer storage life, lasting more than a week in the refrigerator.
• Sugar content in synergistic types take longer to build up than in sugary enhanced types, and kernels can be watery if picked too early.

Varieties:  Honey Select

There are many more varieties available just be sure you are picking a sweet corn that suits your purpose and that you harvest it properly.

Field Corns are dominate so if you are near a huge commercial field you will have to plant, if possible, so your corn does not tassel at the same time as the field corn.

Other types of corn:

Don't limit yourself to just sweet corn.  There are open pollinated, dent, flint, and popcorns.  Sweet corn is eaten in the immature milky stage while other corns are allowed to mature on the stalk until dried and used as a grain to grind into corn meal, animal feed, or popped.

Open pollinated:  If you prefer the old fashioned flavor of corn without the sweetness this is a good choice. One choice that is easy to find is Golden Bantam

Flint Corn:  Flint corn is also known as Indian corn.  There are colorful ornamental cultivars and those that can be used as polenta or ground into cornmeal.  Some varieties I have tried are Bloody Butcher, Hopi Blue, and Polenta

Polenta corn a flint corn

Popcorn:  Technically popcorn is a flint corn that is the best option for popping.  So you are not disappointed movie popcorn is the snowball type and pops bigger than mushroom type popcorns.  There are lots of fun popcorns to try in a variety of colors.  They are actually becoming popular as a gourmet treat.

Dent Corn:  As dent corn dries, a dent is formed in the top of the kernel.  Dent corns are used as animal feed, for corn syrup, and used to make biodegradable plastics.  This probably isn't the choice for the home gardener but and option if you have livestock.

Squash is a good companion with corn.

The tassel which produces the pollen.

Pollination:

Before planting  you need to understand how corn is pollinated.  All corn varieties are wind pollinated and will cross pollinate.  Pollen is produced by the tassel of the corn which is the male part.  A good healthy corn will produce one or more ears along the stalk of the corn.  This is the female part and includes the ear and the emerging silks.  The pollen must go from the tassel to the silk.  This is accomplished with the help of the wind.  Each pollinated silk becomes a kernel on the ear of corn.

The silks of the ear.  Each individually pollinated silk
becomes a kernel on the cob.

Corn pollen is extremely light and can be carried long distances by the wind.  As I mentioned all corn will cross pollinate.  If your corn is tasseling at the same time as your neighbors or a commercial field then chances are there will be cross pollination.

Concerning your neighbor who is probably planting sweet corn. If cross pollination occurs eating quality is affected.  If SU, SE, SU2 are planted together and tassel at the same time they will cross pollinate..  SE and sh2 types are recessive to su types.  Field corn, Indian, and popcorn are dominant.  If planting more than one variety they must have different maturity dates and tasseling times.

Watering and Fertilizing

Sweet corn requires regular consistent watering.  Watering is critical during tasseling, silk development, and ear formation.  Water stress results in stunted growth and poor flavor.

Work a dry fertilizer and compost into the soil before planting. Corn is a heavy feeder. Side dress corn when it is a foot tall with bone meal.  Side dress again when the silks appear.  Also fertilize with fish emulsion at these times.  Mulch when plant are young to keep the wind from drying the soil out.

Corn Earworms

Spinosad and Neem are effective against Corn Earworms.  Female moths lay eggs on tips of corn silks.  The larvae feed off the silks and move on down eating kernels.  They emerge and then pupate in the soil.  You can have 1-4 generations of these lovely creatures. The critical time to spray is when the silks begin to dry.  Focus the spray on the tips of corn and around the base of the corn.

Aphids

Aphids can also be a problem.  An aphid infestation will result in lots of honey dew and can encourage the growth of black mold. The honeydew will attract wasps. While this rarely affects the quality of the corn because it is protected by a tight husk, it weakens the corn and is not pleasant to work around. 

Spinosad and Neem Oil are effective for both of these problems.

Ready to harvest with dry silks, tilted stock and plumb.

Harvesting

Harvest when the ears are plump, silks are dry, and ears tips out.  Enjoy! Sweet corn does not store well in the field.  It does not store long after it has been harvested.  The sugars turn to starch and that great sweet corn  flavor is lost. 

I remove the remaining stalk and some husks and keep it in the refrigerator but don't leave it there long.  Enjoy it fresh. 

To extend the season, I suggest planting two varieties and staggering the plantings so you can enjoy fresh corn longer.  The two varieties I like are Silver Queen and Jubilee.  Both are great for eating fresh and they both process well.  You can freeze corn on the cob or can it in a pressure canner.