Pacific Northwest Growers Can Protect Plants from Heat Waves and Still Have a Good Harvest

Pacific Northwest heat waves have been challenging growers—and their plants—since June. What do these extreme heat waves mean for hemp crop harvest this fall?

Gordon Jones is an assistant professor of general agriculture based at the Southern Oregon Research and Extension Center for Oregon State University.  Jones says well established hemp plants, transplanted in good conditions with proper root growth, can withstand a fair amount of heat stress—as long as they have access to water. 

But with extreme heat come other obstacles like reduced access to water, wildfire smoke and declining worker morale.

“On some grand level, the smoke, the heat, and the drought are connected, and we could probably have a climate change discussion at the macro scale,” says Jones. These challenges make growing hemp in extreme heat a game of survival. However, there are steps farmers can take early on to prevent heat stress and still have a successful harvest.

What is an ‘Extreme Heat Wave’?

The World Meteorological Organization states that a heat wave is when the daily maximum temperature exceeds the average maximum temperature by 9 degrees Fahrenheit for more than five consecutive days. From June 24 to June 29, Pacific Northwesterners experienced a 1-in-1,000-year heat event when temperatures peaked at 116 degrees.

In extreme heat conditions, hemp leaves droop and fold up in a protective measure. If the stress is not mediated, they will yellow and become crisp. Once a plant is matured, there’s not a lot of changes growers can make, warns Cedar Grey, founder of Siskiyou Sungrown, a CBD wellness product brand in Southern Oregon.

For hemp farmers, high temperatures aren’t the only threat to crops and farmers during extreme heat events. "When it gets to that point, your plant is in trouble," he says. "By the time the plant is mature, I don’t think there’s a lot of wholesale changes you can make other than ensuring that your irrigation is on point.”

For some hemp farmers, irrigation is exactly the problem amidst high temperatures and other heat-related challenges.

Challenges for Growing Hemp in Extreme Heat

Heat isn’t the only problem. Water shortages, reduced or adjusted labor hours and questions around the impacts of smoke from nearby wildfires have some farmers wondering if they will reach harvest with a successful yield.

Hemp Plants Are Thirsty: Water Shortage and Restrictions
Kristina Blohkin/Adobe Stock 

The Talent Irrigation District, Rogue River Valley Irrigation District and Medford Irrigation District are part of the U.S. Bureau of Reclamation Rogue Basin Project, where Jones focuses most of his work. These districts supply water to thousands in Oregon, and Jones says water levels have never been so low. “The irrigation season usually runs from April 15 through Oct. 15 in the ideal year," says Jones. "This year, water from those irrigation districts was shut off at the end of and the beginning of August."

Ideally, hemp plants go into the ground in June in Jones’ region. Harvest normally begins in September and will run through October. To have the water shut

More Pacific Northwest Growers Can Protect Plants from Heat Waves and Still Have a Good Harvest