How Hydroponic Gardening Functions

If you've ever submerged a plant cutting in water to encourage root growth, you've already dabbled in hydroponics. This agricultural practice allows plants to thrive without soil by dissolving essential nutrients into water. Depending on the type of system in place, the plant's roots are either suspended in, drenched by, or sprayed with the nutrient-rich solution, supplying the plant with everything it needs for growth.

The word 'hydroponics' comes from the ancient Greek terms 'hydros' meaning water, and 'ponos' meaning work. While often confused with terms like aquaculture or aquiculture, these are more fittingly used in fields unrelated to gardening.

As global populations rise and fertile land becomes scarcer, hydroponics presents a vital opportunity to grow crops in controlled environments such as greenhouses or multi-story buildings dedicated to farming. In areas where land is at a premium, crops are already being cultivated in subterranean spaces, on rooftops, and in greenhouses using hydroponic techniques.

Maybe you'd like to start your own garden to grow fresh vegetables, but you lack space in your yard or are overwhelmed by pests. This article will equip you with everything you need to successfully create a hydroponic garden in your home and recommend plants that thrive with minimal investment.

The Origins of Hydroponics and Soil-Free Gardening

Though it may sound like something straight out of science fiction, hydroponics has actually been practiced for millennia. The Hanging Gardens of Babylon, one of the seven wonders of the ancient world, are widely believed to have operated on hydroponic principles. Constructed around 600 B.C. in Mesopotamia (modern-day Babylonia), these gardens were built along the Euphrates River in an arid region. It’s believed that water was transported using a chain pull system, drawing water from the river and allowing it to cascade through the gardens.

In the 10th and 11th centuries, the Aztecs devised a floating garden system based on hydroponic methods. After being displaced from their homeland, they settled on Lake Tenochtitlan. Unable to cultivate crops on the marshy shoreline, they constructed rafts from reeds and roots. These rafts were topped with a thin layer of soil from the lake's bed and floated in the water. Crops grew atop the rafts, with roots extending down into the water below. Marco Polo's accounts suggest he saw similar floating gardens during his visit to China in the late 13th century [source: Indianetzone.com].

It wasn’t until the 17th century that formal research and publications on hydroponics began. Sir Francis Bacon, a British scientist, philosopher, and politician, conducted studies on soil-free gardening during the 1620s. His findings were published posthumously in 1627 and ignited a surge of interest and research into hydroponics.

In 1699, English scientist John Woodward conducted experiments on the growth of spearmint in various water solutions. He tested rainwater, river water, and water mixed with soil, discovering that the mint grew more vigorously and produced healthier plants in the water that had been blended with soil. His conclusion was that plants thrive better in less pure water than in distilled water. Today, we know that the minerals left in the water from the soil were key to his results [source: Glass].

Berkeley scientist William Gericke advocated for the use of hydroponics in commercial agriculture. He demonstrated the benefits of soil-free gardening by growing large tomatoes at home with water and nutrient solutions. After realizing that "aquaculture" was already a term for aquatic organism studies, he coined the term "hydroponics," which is still used today [source: Jensen].

Two other Berkeley scientists, Dennis Hoagland and Daniel Arnon, later built upon Gericke's research. In 1938, they published "The Water Culture Method for Growing Plants without Soil," considered one of the most significant texts on hydroponics. Many of the nutrient solutions they developed continue to be used today.

A 1938 article in Time magazine reported one of the first commercial applications of hydroponics, based on research at Berkeley. Tanks of mineral-rich water were used to grow beans, tomatoes, and vegetables on Wake Island, a small Pacific island. This island, which served as a refueling stop for Pan-Am Airways, successfully provided food for the airline's staff. Similar hydroponic efforts were made during World War II to grow crops for troops on barren Pacific islands [source: Time Magazine].

Why Opt for a Hydroponic System?

So, why should one go through the effort of setting up a hydroponic system? After all, humans have been cultivating food for millennia using traditional methods with soil. However, hydroponics provides key advantages over conventional farming, and as more people become aware of these benefits, the adoption of hydroponics is set to grow for a variety of agricultural applications.

Hydroponics first and foremost enables food cultivation in places where conventional farming would be impossible. In arid regions like Arizona and Israel, hydroponics has been practiced for decades, offering local populations a chance to enjoy homegrown produce while enhancing food production. It’s also highly beneficial in densely populated urban areas where space is limited. In cities like Tokyo, hydroponic systems replace traditional soil-based methods for plant growth. Additionally, in remote locations like Bermuda, where land is scarce, hydroponics requires only around 20% of the land usually needed for traditional agriculture. This allows locals to have fresh, locally grown produce all year round, without the high costs and delays of importing food. Lastly, hydroponics proves useful in areas with limited sunlight or cold climates, like Alaska and Russia, where controlled environments in hydroponic greenhouses can help extend growing seasons and increase crop yields.

Hydroponics offers notable environmental benefits. These systems use just about 10% of the water required by traditional soil farming. This is possible because hydroponic systems recycle water and nutrients, ensuring no water is wasted. This can make a huge difference in water-scarce regions, like the Middle East and parts of Africa. Additionally, hydroponics generally requires little to no pesticides and only about 25% of the fertilizers needed for soil-based farming. This not only lowers costs but also reduces environmental harm by keeping chemicals out of the ecosystem. Furthermore, hydroponics promotes local farming, cutting down on transportation needs, which results in lower prices and fewer greenhouse gas emissions, as fewer crops need to be imported [source: Jensen].

Hydroponics also offers a faster harvest cycle. Since plants in these systems have direct access to water and nutrients, they don't need to develop large root systems to search for nourishment. This leads to quicker growth and healthier plants, reaching maturity in roughly half the time compared to traditional farming.

Why hasn't hydroponics become the dominant method of farming? There are several key challenges that hinder its widespread adoption. First, hydroponic systems require a significant upfront investment, much higher than traditional soil-based farming. While the long-term costs are typically lower, setting up a large-scale system is expensive. Another issue is the risk of power failure, which can halt pumps and damage crops. Lastly, there's a misconception that hydroponics is overly complex, when in reality, it’s very similar to traditional gardening. Plants need specific nutrients to grow, and these needs don’t change depending on the farming method used.

The Science Behind Hydroponic Nutrients

To fully understand how hydroponics functions, we first need to explore the fundamentals of plant biology. In general, plants don't require much to thrive. A simple mixture of water, sunlight, carbon dioxide, and minerals from the soil is enough for them to grow. Plants have the remarkable ability to convert light energy into chemical energy, which they use to create sugars that fuel their growth and survival. Through the process known as photosynthesis, plants turn carbon dioxide, water, and light into sugars and oxygen. For this process to occur effectively, plants need access to certain minerals, particularly nitrogen, phosphorus, and potassium, which are typically found in soil or are added through commercial fertilizers. It’s essential to note that soil isn’t necessary for plant growth; the plant simply requires these essential minerals. This is the core concept behind hydroponics — all the elements needed for plant growth are the same as traditional gardening, except hydroponics eliminates the need for soil.

Hydroponic systems come in several forms, yet they all share a common foundation. Let’s delve into the various types, explore their functions, and determine which plants perform best with each system.

Ebb and Flow Systems rely on a medium, like perlite, which serves only to provide stability to the plant's roots. The medium itself does not offer any nutrients to the plant. In an ebb and flow setup, a tray is used to hold the plant in the medium. Beneath the tray is a separate container with a reservoir filled with water and nutrient solutions. The water from this reservoir is periodically pumped into the tray, flooding it so that plants can absorb water and nutrients. Over time, gravity causes the water to drain back into the reservoir. Ebb and flow systems are ideal for small plants such as herbs and are commonly used in smaller, home-based hydroponic setups.

Nutrient Film Technique (NFT) is a water-based hydroponic system that doesn't require soil or growing mediums. The setup involves wooden channels lined with polyethylene film. Plants like tomatoes and cucumbers are placed along these channels, and nutrient-rich water is pumped to the higher end. The channels are sloped, allowing the water to flow down and collect at the end, where it’s pumped back through the system for reuse. This technique is best suited for plants with large, well-established root systems.

Drip Systems resemble ebb and flow systems but with a key difference in water delivery. Instead of a single large tube, water is pumped through many smaller tubes, which drip onto the plants. This method is ideal for plants that haven’t yet developed robust root systems, making it particularly effective for smaller plants, much like the ebb and flow system.

Aeroponics is yet another water-based hydroponic system that, like NFT, does not require a growing medium. In this method, plants are suspended on a tray with their roots hanging freely beneath. The tray sits inside a box containing a small amount of water and nutrient solution at the bottom. A pump is used to draw the water up, where it is then sprayed in a fine mist, constantly nourishing both the plants and their roots. Although aeroponics is the most challenging system to set up and maintain, its potential for large-scale commercial use is significant.

Wick Systems bear similarities to ebb and flow systems, as they also rely on a medium. In this setup, plants are placed in a tray filled with a medium like perlite or rockwool. A nylon rope is positioned at the base of each root, hanging freely and extending beyond the tray's bottom. The tray is then placed on top of a reservoir, where the ropes absorb water and nutrients, wicking them up to the plant roots. The major advantage of this system is that it doesn’t require pumps or any additional equipment [source: Roberto].

If you're curious about how to set up the various types of hydroponic systems, continue reading the next section for detailed instructions.

Hydroponic Equipment

Having explored the different types of hydroponic systems, let’s now dive into the tools and accessories that complement these systems and help ensure their success.

The key element in any hydroponic system is undoubtedly the nutrient solution. These solutions, which are readily available at gardening centers and nurseries, are a blend of essential minerals such as nitrogen, potassium, calcium, magnesium, and others. The specific mix of nutrients varies depending on the type of plants being grown, the hydroponic system in use, and whether any mediums are being employed.

As we've seen, hydroponics can be practiced with or without mediums. When a medium is used, several options are available, each with its own pros and cons. Rock wool is one of the most widely used mediums due to its affordability and excellent drainage properties. Other common mediums include clay, perlite, vermiculite, sand, and gravel. While gravel, clay, and sand are inexpensive and easy to find, they tend to be heavy and do not provide as efficient water circulation as perlite and vermiculite, which, though more costly, are far more effective.

Light plays an essential role in hydroponics, as plants rely on it to perform photosynthesis. In areas where natural sunlight is insufficient, High-intensity Discharge (HID) lights are used. There are two primary types of these lights, each emitting light across different parts of the spectrum. Metal Halide (MH) lights emit light from the blue end of the spectrum and are ideal for young plants and leafy vegetables, while High Pressure Sodium (HPS) lights, found at the opposite end of the spectrum, are best suited for fruit-bearing or flowering plants [source: Green Coast Hydroponics].

A successful hydroponic system requires constant monitoring to ensure that the pH levels are within the appropriate range. pH, which measures the concentration of hydrogen ions, determines the acidity or alkalinity of the growing environment. This must be adjusted depending on the specific plants and the medium being used. pH can be tested using a pH testing kit, which can be found at any gardening supply store.

DIY Home Hydroponics

Are you feeling inspired by what you've learned about hydroponic gardening? Ready to roll up your sleeves and create your own hydroponic garden? In this section, we'll weigh the pros and cons of different hydroponic systems and discuss which plants can thrive at home with these systems.

When setting up a home hydroponic garden, it's usually best to include a medium to support the plants. This is especially helpful for systems like ebb and flow or wick. While a wick system is cost-effective and easy to set up, it is less flexible for modifications over time and may result in suboptimal growth. It's difficult to fine-tune the nutrient flow, and if adjustments are needed, they can be tricky. For these reasons, ebb and flow systems are often favored for home use. You can find all the necessary equipment for setting up a home hydroponic system at any hydroponic gardening store, or even at many traditional nurseries.

To get started with your own ebb and flow system, you'll need to gather some essential materials. Here's what you'll need:

If you're willing to repurpose materials you already have, you can set up this system for as low as $50 [source: Bareroots Hydroponics].

To assemble your ebb and flow system, start by placing the plant cuttings or seeds into the plant containers. Use the chosen medium to stabilize them, then position the containers in the plastic tray and place it on the support structure. Next, fill the reservoir with a mixture of three teaspoons of nutrient solution diluted in three gallons of water (11.36 liters). Set up the tubing so that it runs from the top tray to the reservoir, and place the aquarium pump accordingly. Program the timer so that the pump floods the top tray twice a day. Check the PH levels every two weeks, and your hydroponic plants should thrive without issue [source: Roberto].

The easiest plants to grow hydroponically at home are leafy greens like lettuce and spinach. Herbs like basil, mint, and parsley also thrive in hydroponic systems. While tomatoes, cucumbers, and peppers can be grown, they need either ample natural sunlight or supplemental grow lamps. Additionally, small plants and flowers can also be cultivated in this system.

If you're planning to grow light-loving plants and natural sunlight isn't abundant, you might want to consider an artificial lighting setup. HPS lights are ideal for fruits and flowering plants, while metal halides are better suited for leafy greens like lettuce and spinach.

Some plants are trickier to grow using an ebb and flow system. These include potatoes, berries, and bulb-based flowers like daffodils. Although they can be grown hydroponically, these plants tend to perform better in water-based systems such as NFT or aeroponics, which are more effective for large-scale commercial operations.

Food and Hydroponics Labeling

The use of organic labeling in relation to hydroponics is a subject of ongoing debate. As consumers become more mindful of the sources of their food and its effects on their health, they increasingly seek out products labeled as organic. Organic labeling standards vary widely by state, with some states defining organic as crops grown without pesticides, while others insist on a more stringent definition that involves fully natural farming methods. According to the strictest guidelines, natural means plants grown directly in the soil using traditional farming techniques, without any use of pesticides or chemicals, and with tightly regulated plant nutrients.

Depending on the criteria, some hydroponically grown food may be considered organic, as these systems typically do not rely on pesticides or chemicals. However, hydroponics does require nutrient solutions, which are made by extracting or producing minerals and altering them to become water-soluble. Therefore, while hydroponic plants do not meet the strictest definition of organic, they may be classified as organic in certain regions or by some individuals.

When determining whether hydroponically grown crops are right for your needs, carefully examine your state's rules regarding organic labeling. Does "all natural" matter to you, or is your goal simply to reduce your exposure to pesticides? If organic labeling is significant to you, it might be worthwhile to explore this issue further, as hydroponics can produce crops that are considered organic in some regions, often at a much lower cost than conventionally grown organic foods.

Thinking about setting up your own hydroponics system at home? Keep reading for a detailed guide on how to build your system and discover the types of plants you can grow.

Hydroponics Growing and the Future of Agriculture

Hydroponics is rapidly emerging as the fastest-growing sector in agriculture, and it might soon take center stage in food production. With an ever-increasing global population and the diminishing availability of arable land due to unsustainable land practices, new technologies like hydroponics and vertical farming will become essential to meet food production needs. Currently, only about 3 percent of Earth's surface is arable, and with the world population nearing 6 billion, this results in roughly 1/5 hectare (2,000 square meters) of farmland per person. By 2050, projections show that the population will rise to 9.2 billion while the amount of land suitable for farming will shrink. To keep up with this demand, hydroponics will begin replacing traditional agriculture [source: Chamberlain].

To glimpse the future of hydroponics, we only need to look at some of the pioneering adopters of this technology. In Tokyo, Japan, where land is scarce due to the growing population, the country has turned to hydroponic rice farming. This rice is cultivated in underground vaults without any soil, taking advantage of a highly controlled environment. This method allows for four harvests annually, unlike the typical single harvest in traditional farming.

Hydroponics has also proven successful in Israel, a country with a dry and arid climate. A company named Organitech has been growing crops inside 40-foot (12.19-meter) long shipping containers, using hydroponic systems. They manage to produce large quantities of berries, citrus fruits, and bananas, which would be impossible to grow in Israel’s natural environment. The hydroponic method provides a yield 1,000 times greater than conventional land-based farming. What’s more, the entire process is fully automated, with robots controlling an assembly line-like system similar to those used in factories. The shipping containers are then distributed throughout Israel [source: Organitech].

There has been significant excitement within the scientific community about the potential of hydroponics in third-world countries where water is scarce. Although the initial costs to establish hydroponic systems remain high, the long-term decline in technology costs will make this more affordable. Hydroponics has the potential to feed millions in regions of Africa and Asia, where both water and crops are in short supply.

Hydroponics will also play a crucial role in the future of space exploration. NASA has detailed plans for hydroponics research, which will enhance current space missions as well as aid in long-term colonization of Mars or the moon. Since we have not yet discovered soil in space that can support plant life, and transporting soil via space shuttles is impractical, hydroponics could be key to the future of space exploration. Hydroponics offers two significant advantages in space: it could provide a wider variety of food, and it supports a bioregenerative life support system, meaning plants will absorb carbon dioxide and provide fresh oxygen through their natural growth processes. This is vital for long-term habitation of space stations and other planets [source: Heiney].