7 Sweet Corn Planting Tips to Try This Season
Sweet corn celebrates the flavors of summer and the sharing of fresh harvests straight from the garden. Gardening expert Katherine Rowe brings tips for planting the warm season signature to promote the best yields and flavor.
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Sweet corn is a hallmark crop of summer and the most popular “eating” type of corn, with sugary goodness that intensifies when freshly picked from our own garden. With versatility in varieties and a high sugar content, its sweet flavor ranges in intensity.
Sweet corn stands the test of time and is easy to grow in the right conditions. The historic crop has origins in wild grasses that date back 9,000 years. Today, Zea mays is one of the most widely grown crops for its many uses. Some 4,000 years ago, it became a dietary staple when ancient peoples in Central and South America began cultivating and sharing the kernels.
To incorporate the taste of summer into our own edible landscapes, a few planting tips set the foundation for a successful yield. As the weather moves toward spring, we turn our sights to planting warm-season crops for fresh eating and enjoying the season’s sweet bounty.
Sweet Corn Basics
Sweet corn is delicious fresh, raw, and right off the stalk or prepared close to harvest time. Starches that create the sweetness begin to break down as time increases between when it was picked. In addition to their tastiness, the juicy kernels have antioxidants, vitamins A and C, nutrients like magnesium and potassium, and dietary fiber.
Corn is an easy addition to the home vegetable garden, especially with measures to avoid common problems. Each stalk produces one upper ear and a couple of smaller secondary ears.
Choose the Best Growing Site
Be sure to plant sweet corn in full sun where it receives six or more hours of sunlight daily. Organically rich, well-draining soils are the best composition for sturdy stalks and production. They do best in neutral to slightly acidic soil with a pH near 6.0-6.5.
Prep the site by loosening the soil to a depth of ten inches. Amend with compost to add nutrition, aeration, moisture retention, and drainage capabilities, especially in clay or sandy compositions.
Keep Days to Maturity in Mind
Depending on the variety, sweet corn is ready for harvest 60-100 days after planting, or a few weeks after silks develop. There’s a small window to harvest for maximum sweetness, and keeping track of the general readiness timeframe is a guideline for picking at the right time.
Count the days from your planting date to get a jumpstart on knowing when to harvest. This will be on the seed packet as “days to maturity.” Ears usually mature in 60 to 100 days, depending on the selection and weather.
The key indicator for readiness is the silks, which are the threadlike tassels that appear on the tips of the ears. When these turn brown, allow two to three weeks for the ears to be fully mature. In hot weather, they may be ready about 15 days out from when silks brown.
Stagger Planting Times
If you’ve got the garden space, plant a few rounds to enjoy throughout the summer and into early fall. Since stalks produce all at once (or within the same timeframe), staggering the planting time yields multiple harvests. Plant the same variety or use different cultivars suited to early, mid, and late-season harvests.
Corn is open-pollinated. If you’re planting multiple varieties that ripen at the same time, the genetics and qualities may cross. Wind and insects travel between stalks, and the subsequent pollination alters the produce between selections. Your white corn may become yellow, or the flavor may not be as sweet.
Remedy the muddling of the genetic traits by isolating crops 250 feet apart or staggering planting and maturity times. The first option requires a lot of space and isn’t often practical in the home garden. The second one, staggering developing ears, is doable by planting one selection earlier than another or opting for early-, mid-, and late-season distinctions. Allow 14 days between mature yields to prevent cross-pollination.
Sowing and Thinning
Sweet corn plants rely on warm days and nights to germinate and develop. Cool spring conditions can hinder growth and result in fewer cobs. Wait for warm temperatures to sow the kernels. The patience pays off in a hearty return of mature ears as the weather warms.
Direct sow kernels in their garden locations for the least stress on young seedlings. Roots are sensitive to disturbance at transplanting. In areas with short growing seasons, start this crop indoors for transplanting outside as the weather warms. Try to time it so the kernels are only in cell packs for a couple of weeks before moving outside (lessening extensive root development), or opt for soil blocks or biodegradable pots.
Plant kernels one to two weeks after the final frost date, remembering that sweet corn germinates best in soil temperatures above 60°F (16°C) and ideally between 65-90°F (18-32°C).
For best pollination, grow the stalks in blocks rather than long, single rows. Corn grows well in raised beds, too. Sow them in groups of two to three seeds with a spacing of one foot apart (or according to varietal spacing guidelines). Tuck them one to one and a half inches deep at sowing.
Thin seedlings when they reach four inches tall by selecting the strongest and clipping the others below the soil level. Clipping, rather than pulling, minimizes root disturbance for the remaining seedlings. Clip them below the soil to prevent regrowth.
Water Well and Fertilize
At planting, ensure sweet corn has access to regular water from the seedling stage to maturity. An inch or two of water per week is usually sufficient to support the tall stalks, leafy growth, and kernel formation. Supplement with irrigation if regular rainfall isn’t enough. Even moisture is especially important after silks appear and the kernels are developing.
Corn is a heavy feeder, growing and reproducing in a single season. Fertile soils give the best foundation. To supplement nitrogen, phosphorus, and potassium, topdress with a balanced, organic, slow-release granular fertilizer at sowing. Sidedress (scratch in around the base of the plant) with an additional application four to six weeks after seedlings emerge.
Boost Pollination
Before the silks appear, tassels that hold pollen emerge from the tops of the ears. The pollen granules are carried by the wind or travel with insects. Each silky strand needs pollination for all kernels to develop. Weak pollination results in missing rows of kernels.
Draw pollinators by interplanting companion plants and blooming annuals and perennials with nectar and pollen resources. The blooms also serve to attract beneficial insects that prey on pests like corn earworms. Ladybugs, green lacewings, and parasitic wasps feed on the eggs and larvae of the earworm.
You can also hand pollinate by shaking the stalks so the tassels disperse the granules, dropping them onto the silks. Or, snap off a tassel and brush the silks on up to 10 plants.
Check Regularly
Checking the crop every day or two is helpful once the readiness stage approaches. Peak ripeness lasts only a day or two. Upper ears develop first, secondary follow closely behind, and all are generally ready within days of each other.
As silks brown and days pass, take a peek at upper ears to check for readiness. Peel back the husk slightly and poke a kernel. If the juice is milky white, the harvest is ready. Lower, secondary ears are usually ready within a day or two following upper ears. Look for filled-out tips; ready ears will have kernels all around the top and will be tender.
