How to Grow Sweet Corn in Your Backyard
Home Grown Corn
Why Grow Your Own Corn?
Growing corn is an extremely fun experience – the stalks grow quickly and reach great heights, and the formation of the first ears of sweet corn are a great reward for the backyard farmer. Growing your own corn has several advantages:
- You can grow organic, pesticide free corn.
- You can grow unusual varieties not found in the grocery store.
- Fresh corn tastes much better than store-bought corn.
Unlike some backyard vegetables, home grown corn tastes much better than the cobs found in the grocery store. The kernels are far sweeter and crisper, with an unrivalled taste.
The reason backyard corn tastes so much better than the cobs stacked in the produce bin lies in the amount of sugar vs. starch content in the kernels. When corn is picked, the sugars in the kernels immediately start to transform into starch. Since the corn kernels are seeds, the cob produces starch to allow the seeds to have sufficient energy to grow into plants. By plucking an ear fresh off the corn stalk and boiling (or steaming) the ear, you will get the sweetest, best corn you have ever tasted.
Choosing Sweet Corn Seeds
There are many different varieties of sweet corn available on today’s market. There are heirloom seeds, yellow corn seeds, white corn seeds, and unusual, colorful varieties. Sweet corn seeds are marked with labels to indicate the variety. The initials se, su, and sh2 are examples of this labeling system. The table below explains the meaning behind these designations:
Types of Corn
yellow, white, bicolor, mulicolor
Early Sunglow (yellow) and Country Gentleman (white)
yellow, white, bicolor, red
Merlin (yellow) and Double Delight (bicolor)
yellow, white bicolor
Crisp N Sweet (white) and Radiance (bicolor)
yellow, white, bicolor
Cinderella (white) and Charisma (bicolor)
yellow, white, bicolor
Mirai (bicolor) and Montauk (bicolor)
Grow Your Own Corn
Corn Seed Varieties
Standard varieties of corn (labeled su) are the original “sweet corn.” These varieties are sweeter than field corn, but must be picked and cooked quickly to get the best flavor.
Sugary Extenders (labeled se, for sugar-enhanced) have a slower conversion of sugar to starch – these varieties will remain sweet for 2-4 days after they are picked. Some se labeled corn will be labeled with se+ or an uppercase SE: these corn varieties are homozygous (they have two se parents). Other se corn may be heterozygous (have an se parent and an su parent). Ruby Queen (hybrid) is a red version of this corn variety – the kernels are scarlet and the flavor is very sweet.
Supersweet corn (labeled sh2 ) are up to ten times sweeter than the standard (su) varieties of corn. These corn varieties are more finicky with planting conditions and are not nearly as hardy as the su or se types. The label “sh2” comes from the name “shrunken,” as the kernels are so high in sugar content they will shrink and shrivel when dried, as there is little starch in the kernels.
Synergistic corn has multiple varieties on the same ear of corn. Each ear may contain a varying percentage of standard, supersweet, and sugary extender kernels – these corn stalks do not require isolation from other varieties to prevent the formation of starchy cobs.
The Augmented Supersweet varieties have multiple genes for different varieties in each kernel. All of the kernels contain the sh2 genes (supersweet). The kernels will also have genes for se or su in addition to the supersweet genes. These varieties must be grow in isolation, or starchy kernels will form.
Planting Corn Seeds
Corn must be planted in rows – preferably in a block rather than in one long row. Corn is pollinated by wind rather than insects, so planting multiple rows of corn allows for the generation of more ears. Check the individual seed packet for planting depth and requirements, as the needs will vary by the type of corn. In general, most corn rows should be 2' - 3' apart.
One does not require a massive planting field for corn - a 4' x 4' raised garden bed is plenty of room to grow a small plot of sweet corn.
The following steps are universal:
- After the last date of frost, prepare the dirt for planting. If using a raised bed, loosen the soil and remove any weeds. If using flat soil, till the ground and remove any rocks.
- Plant the corn in rows (in general, 4 or more rows are desirable for maximum pollination). Make a furrow approximately 2" deep by dragging a garden hoe through the soil. Place 2-3 seeds every 6" along the furrow. Make three more furrows with 2-3 feet of space between each furrow.
- Water frequently until the first sprouts appear (do not drown the area).
Corn Tassel Picture
Pollination and Ear Formation
There is an old saying that corn should be “knee high by the Fourth of July.” Near the middle or end of July, the corn stalks should reach their final height and produce a tassel (the male portion of the plant) and the ears (the female portion of the plant). The tassel will begin to produce pollen, which falls onto the stigma of the female ears – if you aren’t sure what “stigma” is, don’t worry – it is the corn silk you see on the side of the corn stalk. Each piece of corn silk will pollinate one ovule – and each pollinated ovule will become a kernel of corn. As a helpful hint at the grocery store, the more corn silk a corn cob has, the more kernels it will contain!
When is Corn Ready to Pick?
How Can You Tell When Corn is Ripe?
Nearly every seed packet of corn will state a timeline for the production of corn – some may be as short as 60 days, while others may take 85 days to mature. Mark the date of planting on a calendar to estimate the time when the corn will be ready to pick. Another “timing” method is to count 17-25 days from the time the first silks appear – the corn should be ready to pick within that time frame.
There are several visual indicators that corn is ready to be cooked:
· A kernel will release white fluid (rather than clear) when cut with a thumbnail.
· The corn silk turns brown.
· The husk is completely filled out from top to bottom and may pull away from the stalk (sometimes at a 90 degree angle).
Do not allow corn to get overripe. Indications that corn has been left on the stalk too long include a lack of fluid when the kernels are scratched and dry, papery husks.
Unusual Sweet Corn Varieties
Ruby Queen is an se variety of sweet corn, and produces red kernels. The kernel color is retained when cooked, making this delicious corn a fun and unusual vegetable!
Corn can be scraped off the cob and vacuum sealed, then kept in a freezer until needed. Another method involves the use of a pressurized canner, as corn can be canned and kept for up to a year on a pantry shelf (using a pressure canner). Corn cannot be canned using a traditional water bath unless it is acidified (or pickled), as it is low-acid and is not safe to can using the hot water bath method. Frozen corn retains the best flavor, but canned corn from a backyard stock will taste better than anything you can find at a grocery store.
To can corn, pack quart or pint sized jars with corn kernels (separate from the cob with a sharp knife). Leave about ¾” – 1” headspace, and pour boiling water over the corn to cover them. Shake the jar gently to release any trapped air bubbles. Place sterilized lids and rings on the jars (wiping the rims) and process in a pressure canner (dial gauge) for 55 minutes (pints) at 11 pounds of pressure, or 85 minutes (quarts), also at 11 pounds of pressure. The pressure levels given are for sea level – 2,000 feet: the pressure must be increased at higher altitudes. If using a weighted gauge pressure canner (as opposed to a dial), the pressure is 10 lbs. for sea level – 1,000 feet altitude.