Hydroponics program to continue to grow at Merrimack Valley Middle School

Merrimack Valley Middle School sixth grade science teacher Kristen Bean Warren guides students through emptying the water in their hydroponic growing system on May 29.

Merrimack Valley Middle School sixth grade science teacher Kristen Bean Warren guides students through emptying the water in their hydroponic growing system on May 29. JEREMY MARGOLIS / Monitor staff


Monitor staff

Published: 06-13-2024 12:25 PM

Modified: 06-13-2024 5:17 PM

When students at Merrimack Valley Middle School returned to sixth-grade science teacher Kristen Bean Warren’s classroom on the Wednesday after Memorial Day weekend, they encountered a mystery.

Vegetable plants germinating in a hydroponic growing system in the classroom since March – green and healthy-looking the previous Friday – had suddenly withered and turned brown. Something – but it was not immediately clear what – had happened during the previous five days.

“Is it a root problem? Is it a nutrient problem? Is it a light problem?” Bean Warren asked the nine students in the exploratory class, a quarterly elective program that MVMS offers its students. “You need to come to a conclusion of what our plants are lacking.”

The incorporation of hands-on agricultural projects into Bean Warren’s science courses began in 2020 and has grown little by little since. Next year, it will blossom. Last week, Bean Warren secured a $6,000 grant from the U.S. Department of Agriculture’s Farm to School program to introduce a hydroponic growing system into the middle school’s greenhouse, and to upgrade the greenhouse in other ways.

The grant will allow Bean Warren to expand the agriculture-related growing opportunities in her class, as well as integrate them into other courses at MVMS, including the foods and nutrition class. Eventually, she hopes the greenhouse will also produce enough food to supply the middle school cafeteria and a small food pantry at the Merrimack Valley Learning Center in Penacook.

At first, the greenhouse will focus primarily on growing salad greens, before expanding to other vegetables, such as cucumbers and tomatoes, Bean Warren said.

The agricultural education curriculum that Bean Warren has developed combines experiential learning about plant biology and food production with units on climate change, natural history, and technology. In sixth grade science, a major focus is the scientific method, a concept that lends itself well to the trial and error of growing vegetables.

“Propose your hypothesis, observe what’s happening, collect your data, trial it, revise what you’ve done and then test again,” Bean Warren described.

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As the students dug into solving the mystery behind why their plants had suddenly wilted in late May, they cycled through these steps.

First, they tested the temperature, acidity, nitrate level, and alkalinity of the water and the lumens in the artificial light source shining down on the plants. A couple abnormal findings caught their attention: The nitrate level had risen and the pH – a measure of acidity – of the water in the hydroponic system had dropped, both signs algae had begun to grow in the water system.

Bean Warren presented three potential interventions: They could transplant their plants into dirt, they could transplant them into another hydroponic system that would allow for more individualized control, or they could add nutrients to the current hydroponic system.

After some discussion, the students elected to go with the third option, completely changing the plants’ water supply for the first time since they had originally been planted two months earlier. Because the water travels circularly around the rectangular system, the process of getting the old water out proved arduous: they twisted and tipped the plastic system, at one point resorting to pipettes for a particularly challenging corner. Finally, as the the 50-minute class block came to a close, they refilled the basin, added nutrients to the new water, and reattached the pump.

Two weeks later, Bean Warren provided an update: The plants had made a full recovery.

“They were able to recapture the water through the roots and rebuild their structure and kind of grow their stem strong again,” Bean Warren said.

As school comes to an end this week, the students have transplanted and taken their plants home. With any luck, before the students enter seventh grade in the fall, they will be able to harvest cucumbers, snow peas, and basil from home gardens across the Merrimack Valley towns. It will be but a harbinger of what is to come next year and beyond with an expanded greenhouse at the middle school.

Jeremy Margolis can be contacted at jmargolis@cmonitor.com.