Using Science to Grow Better Strawberries

It’s not your fault, gardeners. Strawberries are not very well suited to this hot, dry climate. That’s why your garden-variety strawberries probably don’t look -- or taste -- much like the plump varieties found at farm stands or grocery stores. But help is on the way.

The fact is, the North Carolina climate is hostile to the so-called “love fruit.” These delicate seed receptacles are more suited to temperate climates, like coastal California, where cool, moist nights help the plant thrive. But strawberries can flourish in more extreme climates, thanks to science and “North Carolina is able to grow strawberries because of all the science and technology that is devoted to the crop,” said Debby Wechsler, executive secretary of the North Carolina Strawberry Association. “It’s really what is known as intense management. It takes a lot of care. It’s not like you just throw them out and let them grow.”

A good example of that intense management can be seen on the Waller Family Farm in Durham, NC. Mark Waller farms 40 acres of strawberries on what used to be a tobacco farm. Customers can pick their own strawberries or visit the market he runs during the strawberry season, which lasts anywhere from April through June.

“Once we see about eight to ten blooms per plant, we really pick up the intensity around the farm,” said Waller. “Not only are we fertilizing but we are also really watching for frost.”

And that’s where North Carolina State University Professor Emeritus Barclay Poling’s research comes in.

“If it’s real humid, with ‘lots of moisture in the air’ type of night, we can get frost or ice crystals on the bloom and we’ve killed blossoms as high as 31 degrees, which is really interesting,” explained Poling. “If it’s a dry night, with a low dew point, in those conditions the flowers can super cool to as low as 27, so that’s quite a range.”

Watch this video to learn how farmers and scientists use digital thermometers to help strawberries thrive in North Carolina.

Poling has found the average critical temperature for strawberry blooms in the state is 28 degrees. If the blooms get much colder than that, they will either stay dormant and wait for warmer weather or possibly die if the cold persists. Because the blooms are the most vulnerable tissue for the strawberry plant, and the most critical to a successful harvest, Poling compiles a wealth of weather information into an alert system to warn farmers of significant weather events during the all-important spring growing season.

And a key tool in this “nurture versus nature” battle is a new type of handheld digital thermometer, which Poling helped develop. Electrodes at one end of a wire are inserted into the strawberry blossoms while the other end of the wire is connected to a digital thermometer. The device reads the temperature of the strawberry blossom. Farmers use those readings together with the weather forecast to decide whether to cover the crops or irrigate them to protect from frost.

And it’s not just protection from the cold: the handheld thermometer is also helpful as the weather gets warm. If the strawberry blossom temperature gets too high, the farmer needs to increase irrigation to cool the plants.

The reality is that for all of the help science has provided to strawberry farmers, Mother Nature is still full of surprises and challenges.

“It’s sort of like going out on a hike and seeing a sign that says ‘unmarked trail,’” said Poling as he smiled and plucked a berry from a plant to examine it. “For all we can monitor and plan for, every strawberry season is an unmarked trail, and so you go out and anticipate what might be happening, but you are never sure.”

So where does that leave you, the intrepid gardener, trying to grow strawberries in this hostile North Carolina environment? Well, you can either invest in one of Poling’s $1,000 thermometers, or you can head to your closest “U-pick” farm, walk the rows, and pick your own perfectly plump strawberries for under $2 a pound.