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As summer brings the heat, gardeners step up to protect their plants

CMU junior Grace Buchholz, one of the first gardeners at the reestablished garden, works on her plants. Courtesy photo from Central Sustainability.
Courtesy photo
Central Sustainability
Grace Buchholz uses the Central Michigan University community garden after it was re-established in 2023.

Michigan has been feeling the heat recently, with July-like temperatures this past week. Even with a recent cool-down, it's projected to be a hot summer that will mean more work for gardeners.

When it comes to extreme heat, watering is key in keeping plants healthy and productive.

Nate Walton is a consumer horticulture educator with Michigan State University Extension in Leelanau County. He said it's best to water in the cooler mornings before temperatures heat up and ideally, with drip irrigation or directly at the roots.

"The risk of watering at night is that the leaves of the plants can stay wet for too long," Walton said. "Especially in cool, dark conditions like in the fall and spring, moisture on the leaves can lead to disease issues."

Frequent and light watering, Walton added, is preferred to reduce nutrient runoff from overwatering.

Walton said mulching with a material like straw is another way to help soil retain moisture and keep the ground cool. A shade cloth to cover plants is also an option, but Walton said it's rarely necessary.

"(A plant) might look wilted or drooping, but that's really an adaptation it's using to protect itself during those hot conditions," Walton said. "For the most part, plants do recover once it cools off and once they get water again."

Walton also said that extreme heat can alter pollen in plants like squash, disrupting pollination and reducing yield.

"Unfortunately, there's not much you can do about that, that's just an environmental situation, and there's no relief," Walton said. "But it does explain if people wonder why their squash plant didn't produce anything (even with) lots of bees and flower production."

According to the National Oceanic and Atmospheric Administration, Michigan's average temperatures have risen by over 2 degrees Fahrenheit in the last 60 years. On average, there are 16 more frost-free days in the year, and heavy rain events have increased by 35%.

Walton said he's not personally noticed changes in gardening habits in the region, but said certain plants like okra, which grows best in warm and humid conditions, have become more popular.

"Okra is a pretty southern plant that can grow in northern Michigan as an annual," Walton said. "What we used to think of as a really good summer, you could get an okra harvest. Now we're having these summers more regularly, where okra can produce a really good crop."

The U.S. Department of Agriculture recently updated its plant hardiness zone map, which is the standard for gardeners to gauge which plants will thrive in their region.

The USDA says the map is based on 30-year averages of the lowest annual winter temperatures at specific locations, and it's not meant to represent global climate trends. However, the zones have shifted northward from the previous 2012 map.

"It can be kind of fun to grow plants that we couldn't grow up here before," Walton said, "but there's definitely a downside we're dealing with that can result in gardening being a little more challenging than it used to be."

Public health officials are also advising outdoor workers to drink plenty of water and take breaks to prevent heat illnesses.

For more tips on how to stay safe in hot weather, check out previous coverage.

Teresa Homsi is an environmental reporter and Report for America Corps Member based in northern Michigan for WCMU. She covers rural environmental issues, focused on contamination, conservation, and climate change.
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