Written by Dale Richardson - Updated: June 23, 2023
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Nothing beats fresh, good quality corn on the cob at a summer barbecue. And there is nothing better that picking this corn right out of your own backyard. Even with a small plot, you can grow enough corn to satisfy your craving.
Prepare your corn plot by working in copious amounts of compost and well-rotted manure. Plant your corn in blocks of at least four rows, with the seeds 2cm to 5cm (1-2inches) deep when the soil has reached a temperature of 18°C (65°F). Keep your corn garden well weeded and watered and harvest when the kernels are juicy and the ears are starting to dry.
Corn is a heat-loving, hungry plant that can be finicky to grow in many locations. Follow these steps for an abundant and delicious harvest.
In general, there are five different types of corn : sweet, popcorn, pod, flint, and field. Most gardeners grow either sweet corn or popcorn, and the other three types are generally used for agriculture purposes (such as flour or livestock feed). There are hundreds of different varieties of each type and it is important to choose one that best suits your growing climate and needs.
Most corn for the backyard garden will take anywhere from 80 to 100 days to reach maturity. However, some varieties take less time and some need upwards of 120 days. Corn needs a long, hot summer for its ears to fully mature, and even more important than the length of your growing season is your heat units .
Read Next: How to grow corn to feed your chickens.
Each day that your corn is exposed to a certain amount of heat will contribute to its heat units. Heat units, also known as growing degree days, accumulate through the summer and fall and corn needs a certain number of days of a sufficient temperature to reach maturity.
If were a nerd like me in school, you will find pleasure calculating the temperature each day using the following calculation:
Corn Growing Degree Day = (Daily High Temp + Daily Low Temp) / 2 - 10°C
By plugging in the day and nighttime temperatures into this equation, you can see if each day is warm enough to encourage your corn to grow. If the results of this equation are more than zero, then that day will contribute to your heat days. If the results of this equation equal zero or less, then that day will not contribute to your heat days. This link goes into more detail about using this equation to calculate your heat units .
Image by Carmen Edenhofer
Thankfully, for all the non-nerds in the garden, there is a simplified way: any day with an average temperature over 10°C (50°F) will contribute to heat units.
For example: If your seed packet says your corn matures in 79 days, this means it needs 79 days with an average temperature of 10°C (50°F) or more each day to reach maturity.
More heat isn't always better
Corn is a very heavy feeder, so make sure you mix in lots of compost or well-rotted manure. Prepare the soil by working in the compost and raking the plot flat. Corn will benefit from growing beside a nitrogen-fixing legume, such as peas . A pH test of your soil might be beneficial and corn prefers a pH between 5.8 and 6.8.
Corn can be direct sown into the garden in late spring. Ideally, corn should have a soil temperature of 18°C (65°F), and even warmer for sweeter varieties. At this temperature, the seeds will germinate in 7 to 10 days with an 85% germination rate. Corn will germinate in lower temperatures, but growth and viability will suffer. If you are expecting a cold, wet spring it is best to start the seeds indoors and transplant them outside when the soil has warmed enough. The emerging seedlings will tolerate a few cold snaps down to 0°C (32°F), and a few heat spikes up to 45°C (112°F), but prolonged periods of time at these temperatures will cause the seeds to freeze and rot, or dry and burn.
Read Next: This is the best direction for a sunny home.
Plant your seeds about 2cm to 5cm (1-2inches) deep. Plant your seeds shallower in heavy soils, cool weather, or if you are growing super sweet varieties. When your plants emerge, you will want to thin them to about 20cm to 25cm (8-10inches), so don't plant them too close together or you will be pulling a lot of healthy plants. Some large-eared varieties need 60cm (24inches) between the plants so make sure you plant accordingly.
Corn is wind-pollinated. Pollen is produced in the tassel at the top of the plant, and wind and gravity blow the pollen to the silks on the ears. If corn is not pollinated properly, there will be blank spaces in the ears where the kernels did not develop. To ensure excellent pollination, plant your corn in a block rather than in a long row. This will help ensure pollen will reach all of the ears as they develop. You want to have at least 4 rows in your plot of corn to ensure successful pollination. If you want to walk between your corn, space the rows between 45cm to 90cm (18-36inches) apart. If this would take up too much space in your backyard, you could plant in a 1m (3ft) wide garden bed, and space your seeds 25cm apart in each direction. This would give you a dense block of corn that you can weed without having to walk through.
Corn is highly susceptible to several diseases and parasites. Your best defence is to grow corn on a 4-year crop rotation. This means growing your corn in a different spot in the garden every year, and not returning it to a previously used bed until four years have passed. This will give any corn-loving parasites and diseases to die.
It is also helpful to grow corn with companion plants, which can help the corn in a mutually beneficial way by ridding each other of pests. We already talked about the benefits of growing peas with corn, but other companion plants for your corn are beans, beets, cucumbers, dill, melons, parsley, potatoes, squash, and sunflowers.
Do not plant your corn with celery or tomatoes.
Image by Carmen Edenhofer
Because corn has shallow roots and loves heat, your corn patch can dry out very easily. If you don't get enough rain (about 2.5cm a week is ideal), give your corn plants a good soaking at least every week. It is also important to keep your corn patch weeded, especially when the plants are small.
Applying a layer of organic mulch, such as straw, will help with both of these chores.
You know when your corn is ready to harvest when the ears start to dry and turn brown. If you cut into a kernel of a perfectly matured ear, you will get a sweet milky juice coming out. Then you know it is time to harvest, shuck the ears and enjoy a delicious fall feast.
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