Getting Geared up for the Sweet Corn Sprint
April 19, 2023 While grand finales epitomize the Fourth of July, the holiday also represents the opening of sweet corn sales in the northern third of the U.S. “Timing to the market — that’s the whole story,” New Hampshire grower Trevor Hardy says. “There’s lettuce and early vegetables, but the cash crop that really brings the customers in at the start of the year is sweet corn. The first farm to have sweet corn starts to get the customers. Some of the customers don’t even care what it costs. Growers will throw money upon money just to get that early sweet corn and then recover it later in volume. So that’s where the growers are willing to spend money on technology to get that first corn.”
According to Hardy, the Business Manager at his family’s Brookdale Fruit Farm, that technology comes in three forms: transplants, clear plastic, and row cover.
Transplants
Some growers in Central New England and northward start corn from seed in the greenhouse and transplant in the field through plastic, typically of the black variety, Hardy says. They then use row cover to fight the occasional spring frost and increase soil temperature.
“This method is the most expensive option, but some growers find it worth-while because when they sell their own corn on the Fourth of July, it’s typically ‘pirate corn’ — a.k.a., ‘buck-an-ear’ retail,” Hardy says. “However, post-COVID, that almost seems cheap.”
Clear Plastic
The most common early-corn practice, clear plastic, is used one of two ways, Hardy says.
Growers typically plant the corn and cover two rows of it with a traditional clear plastic film. Sometimes the plastic has holes in it to ventilate and allow moisture; other times it does not, Hardy says.
Once the corn is about 4 inches tall and pushing against the plastic film, the clear plastic is removed, and the corn is allowed to continue growing.
“The clear plastic is great, adding a greenhouse effect to germinate corn in colder soil temperatures,” Hardy says. “This typically happens in our region from March 29 through April 20, depending on where you’re located. Those planting dates may or may not allow you to get corn by the Fourth of July.”
Since the introduction of biodegradable films, some growers are saving the labor of pulling and removing the plastic. Once the plants are tall enough, they simply cut the bioplastic down the middle and leave it there to decompose.
While some growers do this in a two-step process — plant and then cover — there are growers who follow a one-step process by planting and covering in one pass, Hardy says.
“The hardest thing to manage when planting through clear plastic is herbicides,” he says. “Weeds will germinate under the clear plastic, and if you do not have the right soil, moisture, or temperature for a pre-emergent herbicide at the end of March, the effectiveness of the herbicide is very weak and can cause excess problems with the corn and too many weeds. If the temperature spikes too fast, the herbicide can volatize and hurt the crop as well.”
Growers would then have to compensate by cultivation, hand weeding, and/or applying more nitrogen to allow the early sweet corn to recover, Hardy says.
Covering with clear plastic adds a greenhouse effect, allowing sweet corn to germinate in colder soil temperatures.
Photo: Trevor Hardy, Brookdale Fruit Farm
Row Cover
The third common planting process for early production of sweet corn begins with direct seeding into bare soil, followed by a second manual labor process of covering the corn with large sheets of row cover. The white fibrous fabric comes in widths as wide as 52 feet and row lengths as long as 1,000 feet.
“Row cover has its benefits compared to clear plastic, as it retains a little bit more heat in the evenings and cloudy days when we do not have the greenhouse effect because of lack of sunlight compared to clear plastic,” Hardy says. “However, both methods are somewhat dependent on spring weather to succeed.”
The biggest enemies of row cover are wind and animals, Hardy says. If large sheets of fabric are not proportionally held down in the field with soil, sandbags, or rocks, heavy winds can tear or rip the row cover and ruin the crop. Meanwhile, wildlife, such as deer, turkeys, and coyotes, in the evening can walk through, trample or hunt for mice living under the row fabric and destroy the fabric, causing crop failure.
Growers often choose a method that matches their labor talent available to apply vs. a cost comparison of plastic against row cover, Hardy says. Sometimes, if the weather conditions are unfavorable, they will do both clear plastic and then cover it with row cover to achieve their goals, he adds.
“Row cover has been a larger portion of the market share lately as people are becoming more conscious of plastics in their growing systems,” Hardy says. “However, disposing of used row cover is still a landfill event. Some people choose the less environmentally friendly method of burning.”
Future Option
Hardy looks forward to using the Modula Go seed drill (Forigo), which allows growers to direct-seed sweet corn through biodegradable black plastic. The method is considered an improvement upon clear plastic, Hardy says, because the black material blocks the germination of weeds and the planter seeds through the material, giving the plant a hole to grow out of.
The plastic, being black, heats the soil in a comparable manner to the clear but also allows the grower, if worried about a frost condition, to cover over that crop with a row cover fabric, Hardy says. The black plastic mulch holds the heat in the ground a bit more in the evenings compared to the clear plastic mulch, although it doesn’t warm as fast as the clear in the long run it is a better option.
“This is the future,” Hardy says. “However, we are not there yet with that new seeder since it is brand new and has yet to be adopted by the masses.”
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