Hydroponics… How do you Grow?

February 27, 2018

Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions in water, without soil. Employing hydroponics, Salad Days Produce, a hydroponics farm in Flora, Mississippi, specializes in growing pesticide-free produce and is able to supply warm season crops such as several varieties of tomatoes, lettuce and basil nearly 365 days a year. Started by the husband and wife team of Jamie Redmond and Leigh Bailey, Salad Days Produce is able to produce the equivalent of approximately 5-6 acres of field grown produce in their 18,000 square foot controlled environment greenhouse.   

Wanting to learn more about hydroponics and the benefits of it, I welcomed the opportunity to interview Salad Days Produce Farm Manager, Ethan Norvell. Ethan says even as a kid, he always had an interest in plants. His parents recognized this and turned over control of their whole yard to him where he kept the grass cut, the flower beds blooming and grew food in his backyard garden. While working on his Horticulture degree at Mississippi State University, Ethan discovered Salad Days Produce from a friend who had done an internship with them. Ethan contacted Jamie and Leigh, and they hired him after graduation to be their farm manager. Together, they now grow enough produce annually to supply numerous local restaurants and markets. 

Hydroponics is a method of growing plants using nutrient rich water in place of soil. How is this achieved, exactly? Where does the water come from? How do you ensure the plants are getting enough of the nutrients they need to grow? These are just a few of the questions that I bombarded Ethan with as we started our conversation. With great patience, he walked me through the process step by step. First of all, their water comes from the city. By beginning with city water, they have more control over continuity because they know that the city is required to test its water on a daily basis to keep it to certain standards. At any given time, they can request a copy of these tests and trust that the water is maintained at certain levels. The city water is collected in holding tanks that are partially buried in the ground. A "Fertroller" is then used to control the amount of nutrients in the water. Some of these water-soluble nutrients include magnesium, potassium-nitrate, calcium-nitrate, potassium-phosphate, etc. The nutrients recipe they use for their lettuce and tomatoes was developed from their CropKing Hydroponics plan and the help of the Mississippi State University Extension Service.   

Once the nutrient rich water solution is ready, pumps pull it up and into the grow channels where the plants are. Ethan says, "They look like squatty house gutters!" Employing the Nutrient Stem Technique System (NST), a small stream of nutrient solution is constantly running via gravity through the slanted grow channels while the plants' roots soak up the nutrients they need. The water circulates back around to the tank and is constantly circulating through the channels. This circulation is important so that the water does not become stagnant. Even though the nutrient solution is constantly moving, keeping it from becoming stagnant, it still is replaced once a week. The Salad Days team hypothesized that the longer the nutrient solution was coming in contact with the plants, more and more nutrients were being pulled out of the water. In some cases, the plants were pulling out more of one nutrient than others, causing an imbalance in the nutrient solution and causing slower growth. Therefore, they decided to replace the nutrient solution on a weekly basis to keep their plants growing on schedule. 

Salad Days starts all of their plants from seed, so it makes you wonder how the seeds are not washed away due to the circulating nutrient solution. Using flats with perforated Oasis growing media, they place seed into the perforated slots where they are held in place without being washed away. The flats are then placed onto the nursery channel tables which can hold approximately eight nursery channels in a row. These seed flats get the same nutrient solution as they begin to grow, and once the plant reaches a certain size, they transfer them to the regular growing channels. 

Although the nutrient solution is very important for the growing process, there are other environmental factors that play a big part, as well. Air flow, sunshine, and temperature are very important for plant growth. Plants need sufficient airflow around the whole plant, explaining why the channels are on tables and not sitting on the ground. Fans are used year round to ensure good airflow circulation throughout the greenhouses. Sunshine is important to plants because sunlight is energy for the plants. Plants are classed as autotrophs, which means that they produce their own food. To do this they require an input of energy and this energy is provided by sunlight. Therefore, the amount of sunlight a plant receives will affect its rate and amount of growth. Some farms use artificial lights to supplement the amount of light the plants are getting. Temperature is another important factor for growing plants. Ethan says. "The optimum temperature is 60-70 degrees for lettuce and 70-80 degrees for tomatoes during the daytime, but at night you want the temperature to be 10 degrees cooler." At Salad Days Produce, they use temperature controllers and set the daily parameters each morning based on the day's forecast.

Understanding these growing factors and working to keep them at the optimum levels ensures good, healthy plant growth. Problem-solving skills are used on a daily basis as they hypothesize.

However, even though everything seems to be in a controlled atmosphere, sometimes harmful insects still reach the plants. Plants are inspected daily to make sure they are healthy. Ethan says, "If they see the beginning of a problem, they use an insecticidal soap first, and then a week later, they will introduce bugs such as lady bugs, lacewings, parasitic wasps or parasitic mites to combat the harmful pests." By using these natural means to fight the pests, Salad Days is able to keep their plants healthy without using pesticides. Another insect used in the tomato greenhouses is bees for pollination. The bees are kept in the tomato greenhouses year-round.  

Ethan says, "There is nothing you can't grow in a hydroponics system." Hydroponics has many benefits including local produce that keeps money in the local economy, product that is fresher without the bumps and bruises of being shipped, more consistent flavor thanks to growing in a controlled environment, and the plants are grown in smaller space, not taking up acres of land. For instance, Salad Days can grow the same amount of produce in their 18,000 square foot hydroponics facility as it would take 5-6 acres of land to grow the traditional way in soil.  

A hydroponics system can be as large or as small as you want it to be, even making it ideal for growing produce in a classroom setting. Internet research, local hydroponics farms, and local colleges or universities would be a great way to start learning how you can have your own hydroponics system right in your classroom. Students will boost their own creativity, confidence and classroom engagement by growing and being responsible for these plants. Plus, it will help promote their problem-solving skills, and the pride they will have in their finished product will bring you great pride, as well. 

Stephanie Miller

With over 25 years experience, Stephanie serves as a senior copywriter, social media director, and senior editor for Science Scene. Stephanie is always on the lookout for new educational and STEM-related opportunities and technology.