March 2019 Controlled Environment Agriculture

Four Tips to Success in Hydroponic Growing By Dean St. Laurent

By 2050, studies have shown that there will be a jump in the Earth’s population from 7.3 to 9.8 billion people. The significant uptick will cause food production to increase anywhere from 50 to 98 percent in the next 30 years. This is a concern for many growers because available land for crop production is on the decline.

Thankfully, current trends are leading to many growers veering away from traditional growing techniques toward hydroponic growing because it is more versatile, and the systems can be placed anywhere, from greenhouses to bedrooms. In hydroponic systems, plants are grown in a growing medium, and a mixture of water and fertilizer is distributed, promoting quality growth.

Originated from two Greek terms, “hydro,” which means water and “ponos,” which means work, hydroponics has come a long way and is turning into the future of farming. It is a challenging growing technique to conquer for someone who doesn’t have a background in it, but here are four tips on how to maintain a successful hydroponic growing operation.

ENSURING WATER QUALITY

It is essential for growers to test the quality of their water supply before introducing it into a hydroponic system. The pH measures the acid or alkali levels in the water and are important to keep track of with a pH meter or pH strips. The pH scale runs from 0.0 to 14.0; 7.0 is neutral, less than 7.0 is looked at as acidic, and above 7.0 is alkaline. The pH levels growers want their water to be within is between 5.5 and 6.5 in most hydroponic systems, but where pH levels stay is determined by a grower’s preference and the type of plants being grown in the system. Multiple nutrients are absorbed at different rates, so required pH levels can fluctuate depending on the type plant or where the plants are in their life cycle.

No matter what kind of plant is being grown in a hydroponic system, sufficient EC levels are required in a grower’s water supply to sustain healthy plants. EC measures the amount of dissolved salts in the water, which are the nutrients and background minerals plants need to remain healthy. EC directly correlates to the nutrients available to crops, and is why it is so important to test EC. The good thing is growers can test their EC levels with EC meters that when placed in the water pass an AC voltage between them indicating the conductivity of the water.

The water temperature in any hydroponic system should be between 68 and 72° F. Growers can maintain their water temperatures with a water heater and water chiller. This ensures that the water being distributed to the plants isn’t too warm or too cold.

Will Kacheris, who designs custom hydroponic systems for GrowSpan Greenhouse Structures and Hydro Cycle Growing Systems, adds, “The use of aeration and a UV sterilizer can help growers with water that is not feasible to chill. It keeps down disease and it keeps dissolved oxygen levels higher, so the plants can grow quicker. Aeration of the root zone with a bubbling mechanism, such as airstones, also helps to keep roots clean so they can absorb nutrients freely.”

INTRODUCE A FERTIGATION SYSTEM

Fertigation is the process of injecting fertilizers into an irrigation system. In hydroponic growing the right distribution of fertilizer into the water supply is critical, because the plants are being grown without soil, relying on the right amount of water and nutrients to survive.

Kacheris further emphasizes why precise fertilizer distribution is so important in hydroponic growing, “The soil usually provides a buffer for salts, acids and bases added to the system, without this natural buffer, growers
have to be careful not to shock the plants with
an overdose of a chemical.”

Applying the right amount of fertilizer can be challenging because when the nutrients are mixed into the water supply, the pH levels must still be at the right levels for the plants to absorb the right amount of the nutrient solution. This can be timely without a fertigation system because it means the grower will have to manually pour, mix and test, using a trial and error process until the pH levels are correct.

Implementing a fertigation system will make the process more efficient. Kacheris states, “The plants remain more stable and are fed regularly, leading to optimal growth.”

It won’t eliminate having to test the pH levels, but it will make it so that the right amount of fertilizer is distributed every time more precisely, making the process smoother. Growers should calibrate their system at least once a month, ideally once every two weeks, to ensure the right amount of fertilizer is being applied, and to make sure pH levels are where they should be.

“Rising labor costs in the agriculture industry have been a large reason for growers to automate the fertigation system,” Kacheris explains. “Compared to a salaried employee, the system will pay for itself in a few months and will last for years and years.”

CHOOSE THE RIGHT GROWING MEDIUM

The absence of soil in a hydroponic system means there must be something that the plants can be propagated in and supported by for the nutrient solution to flow effectively through. The determination of a good growing medium is one that allows a good balance of oxygen and moisture to be absorbed by the roots of the plants.

The combination of clay pebbles and coco coir is often used in hydroponic systems because the combination retains oxygen and moisture at an elite level. Clay pebbles are clay pellets that are inexpensive and known for retaining oxygen at a high level and coco coir is made from coconut husks that can easily stand alone as a good medium in both areas, but is expensive. Therefore, mixing it with grow rocks is often done to keep down costs.

Rockwool is another medium that is used frequently because it is like coco coir. It is great at retaining both oxygen and moisture and is manufactured in cubes allowing plants to be easily placed in rows. The downfall is that it must be thrown out after just one use.

CLEAN THE SYSTEM REGULARLY

Lastly, all these tips can be done perfectly, but if the system is dirty and contaminated it won’t matter. Cleaning a hydroponic system regularly is a crucial part of maintaining a successful operation because it keeps a system free of pests and diseases.

After completely sterilizing the entire grow room growers should clean the nutrient solution reservoir. It is done by emptying the reservoir, filling it back up halfway and using a deluded bleach solution for an effective clean, ensuring there is no solid material buildup in the tubing. Reservoir cleaning is usually done every two to three weeks, but cleaning frequency depends on how busy an operation is. Clogging can also be avoided by opening the valves for a few seconds once a week.

Scrubbing down the buckets or grow trays also is important in the cleaning process to avoid pathogen buildup. This process is simple and can be done by using a scrubby and 10 percent bleach solution. A grower would apply the bleach and scrub until they are spotless and then rinse them out to finalize the process. This is usually done after each growing season or after every harvest.

There it is, a few helpful tips that any grower can use to run a successful hydroponic growing system. Maintain a healthy growing environment, ensure good water quality, implement a fertigation system, choose an effective growing medium, clean the system regularly, and you’ll find your operation set up for success