Schools with limited outdoor space and teachers who are uncomfortable with traditional agriculture are turning to aeroponic tower systems to grow food for the classroom. Cobb County Cooperative Extension office has installed one of the systems in their office and have had a few harvests of leafy greens and herbs. I recently talked with Daniel Price, a Cobb Extension program assistant, about the system.
How the Tower System Works
Aeroponics are a subset of the older hydroponics. They both are soilless systems that rely on a nutrient water blend. As a college student, a long time ago, I worked in a hydroponics lab. The nutrients flowed continually around the plant roots in an open system. We were continually concerned about bacteria and viruses infecting the nutrient system. Things have changed with the updated aeroponics.
In aeroponic tower systems seeds are germinated in a special media called rockwool. Once the seedlings grow a few true leaves they are moved to the tower system. Cobb County’s tower example has 20 plant spaces with an outer ring for plant support.
The nutrient water blend is housed in a 20-gallon drum at the bottom of the tower. The blend is rained on the plant roots for 15 minutes per hour. The system is enclosed which helps limit contamination of the nutrient blend. Plant lights surround the tower and are on a timer. Basically once the system is set-up everything is automatic until you are ready to harvest. Daniel says that it takes 2-3 weeks from lettuce seedlings to a full harvest.
Issues to Consider
*This tower system cost approximately $1,000. This included the hardware, seedling starter kit, pH tester, pH buffer, and a start pack of nutrients.
*Leaks are sometimes a problem if the tower is not on very even ground.
*The pH needs to be routinely monitored but if it falls out of the recommended range, it is not too difficult to adjust.
*Algae growth is common around the rockwell plug and most experts do not think it is a problem. It just looks concerning.
*This system does not totally eliminate pest and disease issues.
Cobb Extension personnel are happy with the system. They have enjoyed the harvests and have not had any serious issues. Although they have only grown leafy greens and herbs at this point, the plan is to expand the plant selections. Daniel uses the tower as a teaching tool and has held several classes about aeroponics. Cobb Extension encourages anyone who wants to see the system at work to visit their office.
Thanks, Daniel, for showing me around the aeroponics system!
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