The Science Behind Hydroponic Food Systems

Did you know that some crops don’t need soil or sunlight to thrive?

Without realizing it, you may have eaten a tomato or strawberry grown in a hydroponic food system, where plants are raised outside the ground. In an alien world of pipes, troughs and drip systems, fruits and vegetables flourish in lush greenhouses that are expertly tailored to their needs. 

Although it may seem futuristic, people have been growing plants in water for at least several hundred years, and perhaps even longer. Here’s the science behind the spectacle of hydroponic food systems. 

The Basics of Hydroponic Systems

A hydroponic setup looks a lot like an ordinary greenhouse, but you won’t smell the signature aroma of soil or manure. Instead, rows or racks of plants thrive in tubs, pipes or trays of water, often in a strikingly uniform grid that hints at the tight laboratory conditions of the farm. The crops may even grow vertically around a tube that pipes water to their roots, resembling a sort of prehistoric tree with leaves projecting from the trunk.

Most hydroponic food systems are built indoors. They have numerous advantages over traditional farms, including:

• Not having to pull weeds, which saves time and labour costs

• Saving water by eliminating evaporation and reusing it for multiple harvests

• Producing food year-round in stable conditions

• Being able to plant crops very closely together

• Not needing to spray pesticides since few insects get indoors

• Growing crops in urban environments

With world hunger on the rise, innovators are looking for novel ways to produce more food in less space. Gardeners can grow cucumbers or lettuce several storeys up in a skyscraper or in the corner of an office building. Peppers can flourish while a blizzard rages outside. 

Hydroponic food systems marketed toward apartment dwellers have even begun popping up on social media. Free from the constraints of soil, plants can grow in some pretty unexpected conditions. That’s good news for the growing global population. 

Thriving Indoors

So, how does it all work? 

In primary school, you probably learned that plants need three key elements to survive: sunlight, soil and water. Remove the first two from the equation, and under normal conditions, a plant will die. 

However, a hydroponic food system doesn’t replicate normal conditions. The crops aren’t at the mercy of wind and rain, which would normally blow away any plants not anchored in the ground. 

Instead of plain water, the plants receive a nutrient-dense liquid in an aqueous solvent. This supplies the minerals they’d normally get from the soil. Since the hydroponic setup constantly delivers this fluid, the plant doesn’t have to exert any energy sending its roots out in different directions searching for nutrients. 

Rather than sunlight, which can make the temperature vary unpredictably or burn leaves under its glare, plants in a hydroponic farm bask in the glow of special LED lights. The conditions are just right for plants to grow faster, bigger and healthier than traditionally grown crops. 

Certain plants don’t do well in hydroponic food systems, though it might surprise you which species make the cut. Corn and carrots are nearly impossible to grow hydroponically, but many cacti — against all logic — take to it very well. Certain plants can also be genetically modified to perform better in hydroponic setups. 

Different Types of Hydroponic Food Systems

All hydroponic farms have one thing in common: They grow plants outside the ground. However, a few distinct growing systems can be used in various circumstances. 

Nutrient Film Technique

You’ve probably seen the acronym “NFT” a few times, but in this case, it stands for something real and tangible. The nutrient film technique involves placing plants in hollow, sloping pipes. They receive a steady supply of nutrient-dense liquid, which flows over their roots, through the lines. It’s a closed system that continuously recirculates water via a pump system. 

Wick System

In this hydroponic setup, plants sit in a growing medium, such as perlite or gravel, that contains a long wick. The wick hangs down into a reservoir of liquid under the container, soaking up the nutrients through capillary action and continually delivering them to the roots. This is a very easy setup for beginners looking to build their own hydroponic garden. 

Ebb and Flow Technique

The gardener embeds plants in a growing medium and suspends them over a liquid reservoir. A pump attached to a timer forces water upward until it soaks the roots, then lets the water recede again. It does this several times a day, lending this technique its name. 

Aeroponics 

Plants are suspended in the air along a pipe or in a basket, either vertically or horizontally. A pump sprays nutrient-rich mist directly onto the roots — continuously or on a timer — to keep them moist and healthy. This advanced hydroponic technique requires pumps, timers and mist sprayers. 

Drip System

This technique is akin to rehydrating someone through an IV. A pump moves water from an underlying reservoir through drip lines, which are directly connected to the pots, and the water flows through them into the growing medium holding the plants in place. This supplies the crops with a slow, steady trickle of liquid. Gardeners can recycle the water continuously through the drip lines. 

Deep Water Culture Technique

Plants float in pots directly on the water’s surface, and their roots extend into the water. A pump continually oxygenates the tank. Unlike the nutrient film technique, this system is open, meaning the water can evaporate. 

This can even be combined with a technique known as aquaponics, where fish live in the water tanks. The fish and plants form a symbiotic relationship — the plants oxygenate the water, and the fish provide fertilizer back to the plants. 

The Future of Farming

With the acceleration of climate change and dwindling land availability, it’s more challenging than ever to feed the growing population. Luckily, thanks to advances in technology, hydroponics is shaping up to be a promising solution. Though it doesn’t work for every crop, hydroponics might be the next revolution in agriculture.