Nothing tastes like a fresh cob of homegrown corn, just picked from your garden. Growing corn from seed in zone 3 and other cool growing climates can be a challenge. In this blog post I will share with you my tried and true tips on how to grow corn in Alberta, Canada along with other short season growing climates.
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Best Conditions for Growing Corn
Many varieties of sweet corn take at least 70 to 80 days to mature. This is in ideal growing conditions. The best temperature for growing corn would be 85⁰ to 90⁰ F (around 30⁰C). I don't know about you, buy my average growing temperatures are much cooler than that! When growing corn in cool climates, expect it to take at least 20 additional days to mature than listed on the package.
What Corn Grows Best in Zone 3?
When shopping for corn seeds select seeds with the fewest days to maturity you can find. Anything listed as 70 days to maturity or less is a good choice. West Cost Seeds carries the varieties Sugar Buns and Peaches & Cream which are both suitable corn varities for growing in cool climates.
Soaking Corn Seeds Before Planting
Corn seeds can be soaked for 24 hours prior to planting them to help speed up germination. Corn seeds don't have to be soaked, it comes down to a matter of preference. If you choose to soak your seeds, make sure you drain the water, rinse the corn seeds well, and replace with fresh water every 8 hours.
When to Plant Corn
Corn can be direct sown outdoors when night temperatures are consistently above 50⁰F (10⁰C). If you can not expect to have more than 90 days after this would occur to grow your corn, start your corn seeds indoors around April 30th, or one month before your last frost.
Use deep, narrow pots for growing corn seedlings indoors because their roost will want to go deep.
When starting corn indoors from seed, make sure you harden it off prior to transplanting corn seedlings outdoors.
Planting Spacing for Corn
Each developing kernel of corn sends out a silk strand. Each individual strand is pollinated when the wind carries the pollen from the corn tassel to the silk. It then develops into a kernel. For this reason, planting corn in a block of at least 3 x 3 plants verses in a row leads to better pollination and kernel development.
Plant corn seeds or seedlings 10 inches apart and 1 inch deep. Rows can be anywhere from 10 inches apart to 2.5 feet apart. Your row spacing will depend on whether or not you need to be able to walk down it. If growing corn in a raised bed, plant in a grid with 10 inches between each plant.
Keeping the Soil Warm for Corn to Grow
There are a few different options that can help you to keep your soil warm and allow your corn to grow quicker.
First off, select the hottest part of your garden, somewhere in full sun, to plant your corn.
If direct seeding, you can place an upside down jar over each corn seed to act as a mini greenhouse, keeping the soil warm. This can stay on until after your last frost date. You could also use the top half of a milk jug. If using a milk jug, remove the cap to allow moisture to escape once the corn has germinated.
Use black plastic mulch to cover your soil and to plant corn in. This helps to keep the warmth in the ground, allowing corn to grow quicker in cool climates. If using this, you will need to run a soaker hose underneath to water, or water in each individual hole.
Start corn seeds or transplant seedlings into a polytunnel or cold frame. If you are able to use a plastic dome over your corn, this will help keep it warmer during the sometimes cool month of June.
Knee High by 4th of July
There is an old saying that your corn should be knee high by the 4th of July. If you can achieve this, you are on track for a great harvest!
How to Tell When Corn is Ready to be Picked
Corn is ready to be harvested when the silks begin to turn brown and when you gently squeeze the cob and can feel the plump, developed kernels underneath, all the way to the top of the cob. If you pick too early, there may be many undeveloped kernels.
Once it has ripened, you will want to pick it in the next 7 to 10 days. Corn becomes overripe quickly. This took me by surprise the first year I successfully grew corn and I didn't harvest it soon enough. Unfortunately the chickens got to enjoy much of that corn crop.
How to Grow Corn in Raised Beds or Pots
Corn grows well in raised beds as long as the soil is deep enough to support the plant. When growing corn in a raised bed or large pot, select a short variety corn. Minimum soil depth is 1.5 feet of soil. As mentioned above, corn should be planted in a block of at least 3 x 3, making it difficult to grow in pots. If you are growing corn in a pot try to find one AT LEAST 3 feet in diameter and 2 feet deep.
Growing a 3 Sisters Garden
I love to grow my corn in a 3 sisters garden along with pole beans and squash. Find out more about growing a 3 sisters garden here.
Companion Plants For Corn
Companion plants for corn include beans, beets, cucumbers, dill, artichokes, marigolds, nasturtiums, melons, parsley, peas, potatoes, squash and sunflowers.
Avoid planting corn near celery and tomatoes.
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