How Does Hydroponics Work?

It’s no secret. People enjoy being around others who can provide for themselves. What could be more providing than feeding you and your loved ones?

If you’re like me, you’re poor and live in a small flat. That makes feeding yourself slightly more of a challenge than you’d like. How, then, can it be done?

The answer, friends, is hydroponics.

how does hydroponics work?

Hydroponics is the growing of plants without soil and instead supplying all of the necessary elements for survival in water containing dissolved nutrients.

Imagine eating all the organic, juicy tomatoes you can eat, straight from your window sill. What a world we live in. You provide every ounce of nutritious food for these organisms, and in doing so, your fruit and veg don't waste valuable energy going in search of it themselves. Hence more efficient growth and a tastier salad.

Their sardine-like packing together means you have the opportunity to grow more food in the same amount of space.

Then, we dine.

If saving space isn’t enough of an incentive to grow hydroponically, you’re a heathen. If you don’t mind being a heathen then how about this?

You can stop the Water Wars before they even happen.

Growing in soil wastes a lot of water. Aside from the amount dumped on the patch of ground, there’s also the spillage, leakage, and evaporation to consider.

A tiny percentage of water used reaches your plants.

Hydroponics is essentially a closed system, and water is only lost from it if the plants suck it up through their roots.

Most setups circulate the nutrient solution with a pump, limiting the amount of water necessary to produce crops with a higher yield because the plants only consume the volume they require.

I don’t know if you’re aware, but global warming is happening. There’s going to be less water available, and when a resource is limited humans tend to not get along so well.

Let’s all perform our civic duties and stop the water wars now.

Summary: Saves you space and saves the planet.

You’d be forgiven for thinking such an agricultural technique was a recent invention. However, legend has it the Hanging Gardens Of Babylon were hydroponic creations. Not bad, Babylonians.

That was 600BC. Fast-forward a few years to 1699 and John Woodward, a British scientist, had figured out mixing soil and water created a delicious root media. He’s considered to be the first person to create a hydroponic nutrient solution.

In 1924, Dr William Gericke is growing tomatoes 25ft in length, simply because the man could. We can all thank Dr Gericke for coining the term hydroponics.

And today?

Commercial and amateur growing is steadily on the rise.

For example, Thanet Earth, which is based in the UK, grew a whole lot of fruit and veg in 2013.

Approximately 225 million tomatoes (12% Britain’s tomato production for the year), 16 million peppers (11% of the year’s peppers), and 13 million cucumbers (8% of the year’s cucumbers).

“Is it worth a lot?” I hear you cry.

Global hydroponic farming was reportedly worth $21.5 billion in 2015.

According to the World Bank Group, we need to produce at least 50% more food to feed the estimated 9 billion humans that’ll be inhabiting the planet. Climate change may well destroy 25% of our traditional crop yield by then, too.

Why am I telling you this? You’re just thinking about growing some herbs in your greenhouse.

I’m emphasising that hydroponics isn’t just some fad, or trend waiting to die off. It’s something the world needs in a big way.

Let’s delve a little deeper, shall we?

We’ve written a glossary of terms here you can peruse at your leisure.

Glossary

Aeration	Refers to the number of pockets of air within the soil. Hydroponic systems normally use pumps to provide the water with suitable levels of oxygen.
Aeroponics	A fine nutrient mist is supplied directly to the exposed roots of plants being grown
Acid	A solution with a pH <7, reference to ericaceous plants which thrive in sulfur-rich soil or nutrient supply
Alkaline	A solution with a pH of >7, references plants which thrive in sodium-rich alkaline soil
Bloom Booster	Phosphorus-rich fertiliser used to increased flower yield
Boron	Chemical element thought to aid carbohydrate transportation, common deficiency among many plants
Burn	Tips of leaves darken through too much fertiliser and salt
Calcium	Important for carbohydrate translocation (movement of materials from the leaves to the rest of the plant) as well as healthy cell wall integrity and root strucure development
Carbon Dioxide	Essential compound for photosynthetic processes found naturally in the atomosphere
Chlorine	Essential element for photosynthetic processes, enables enzyme activation for the removal of oxygen from water
Chlorosis	Loss of green colour in plant leaves caused by iron deficiency soils rich in lime, disease or lack of light
Clone	Identical copy of parent plant through asexual reproduction, including plant cuttings
Copper	Electron carrier during photosynthesis as well as being necessary for lignin synthesis, respiration, and carbohydrate and protein metabolism
Damping-off fungus	A disease of seedlings caused by several fungi, typically caused by over-watering and usually occurs when plants are grown indoors
Dissolved solids	Usually refers to the concentration of nutrients dissolved in water in parts per million
Drip System	A type of irrigation system which saving water and fertiliser by allowing water to drip directly into the soil or root system, thereby slowly the water down
Ebb And Flow	Pots filled with inert medium to anchor the root system are repeatedly flooded with water and dissolved nutrients which is then allowed to drain away
Foliar Feeding	Providing nutrients to plants via a nutrient-rich mist applied to the leaves
Fungicide	A chemical compound which kills fungus
Fungus	Unicellular or multicellular eukaryotic organisms that are niether plants or animals.
Germination	The process involved in a seed developing into a plant
Harden-off	The acclimatisation of a plant to a newer, harsher environment.
Hybrid	Hybrids are offspring produced after pollination of two different varieties of the same species of plant
Hydrated lime	Calcium hydroxide used to raise the pH and thus lower the acidity
Hygrometer	Atmospheric humidity measuring tool
Iron	The element is necessary for chlorophyll production along with carbohydrate synthesis, and enzyme activation
Leaf Curl	Leaf abnormality due to several factors including: magneisum deficiency, overwatering, and insect/fungal damage
Macronutrients	Primary nutrients sodium, phosphorus, potassium and secondary nutrients magnesium and calcium
Manganese	A micronutrient with many functions, primarily used in photosynthesis. Additionally involved in pollen germination and DNA/RNA production
Medium	Material in which plants sit whether that be soil, gravel, water to absorb and release nutrients.
Micronutrients	Essential to normal functioning but present in very small amounts, elements include sulfur, iron, manganese, boron, copper
Molybdenum	A micronutrient needed for the fixation of nitrogen and the reduction of nitrogen
Necrosis	Tissue damage and death sustained through mineral deficiencies or microorganism infection
Nitrogen	Element necessary for the overall growth of plant and specifically chlorophyll development.
Nutrient Film Technique	Nutrients are distributed across the surface of water, forming a thin film. Root systems hanging from above are in continual contact with nutrients and oxygen from the air
Nutrients	Necessary elements for survival of the plant. Elements that are needed in abundance are called macronutrients and elements that aren't used in a lot of processes are called micronutrients
Nutrient Solution	Essential dissolved elements for plant survival are supplied in a water system in hydroponics
pH	pH is a scale ranging from 1 to 14 measuring from acid to alkaline. In hydroponics, this is a measurement of water nutrient solution which most plants prefer to be from 6 to 6.8
Phosphorus	Essential macronutrient necessary for the root system growth as well as speeding up maturity of the plant.
Potassium	Essential macronutrient used in many processes. More specifically, for the opening and closing of stomata which regulates carbon dioxide levels throughout the plant.
Perlite	A plant growth medium consisting of volcanic glass that holds onto water and nutrients
Photoperiod	The length of time an organism receives daylight
Photosynthesis	The synthesis of carbohydrates from carbon dioxide via the absorption of light
Pyrethrum	An organic insecticide snythesised by the blossoms of chrysanthemums
Reservoir	The base where the nutrient solution sits for the plant to absorb it
Rockwool	inorganic, matted material used as a growing medium where it holds a nutrient solution
Systemic	Referring to the plant in a holistic manner - especially when it comes to disease
Vermiculite	Growing medium that holds onto a lot of water produced from hydrated laminar minerals
Waterlogging	When a root system does not have the necessary aeration due to too much water in the soil/during hydroponics
Wick	A wick is tangled into the nutrient solution and absorbed up it where it's then transferred to the root system
Zinc	Essential micronutrient for hormone production and chlorophyll synthesis.

Equipment

Different hydroponic techniques set up in slightly different ways but the main supplies you’ll need remain primarily the same.

What you’ll need:

Air Pump

Water Pump

Reservoir

Grow Tray

Grow Lights

Timer

Growing Medium

Nutrients

pH Testing Kit

Air Pump

Plants, like most living organisms on Earth, love oxygen. Because your hydroponics system is relatively small and the plants are greedy, you need to continuously replenish it with an air pump.

Water Pump

Water pumps take the nutrient solution from the reservoir and distributes it onto the plants in the grow tray and back to the reservoir if necessary.

Reservoir

The nutrient solution you’ve concocted sits here. You need to ensure the size of the reservoir is big enough to fits the number of plants you’re growing, the bigger the better.

Water pumps reside here and air pumps feed into it, you’ll need a suitable cover over it preventing any evaporation.

Grow Tray

This is where the magic happens. Grow trays hold your plants and are accommodated within the reservoir. They allow the plant’s roots to either partially or permanently make contact with the nutrient solution.

Grow Lights

As we’re sure you learnt in biology, photosynthesis needs light. Plants convert the light into carbohydrates which are then used to grow.

Timer

Timers underpin all of the autonomous functioning of your hydroponic systems. They’re used with water pumps, grow lights, heaters, ventilation.

We don’t live in the dark ages so we’re going to need some digital timers, not analog.

Growing Medium

Growing medium tends to be an inert material that doesn’t provide any nutrition, but allows the roots to get a firm grip and support the rest of the plant.

Nutrients

There are certain macronutrients and micronutrients necessary for plant growth. These are soluble and added to the water and soon you’ll be eating them as vegetables.

pH Testing Kits

Plants are fussy and know what they like. Unfortunately, that’s nothing too acidic, and nothing too alkaline. Their response? Death.

Use the pH testing kits to adjust accordingly.

Now you’ve an understanding of the equipment necessary for hydroponics it’s time to learn how the setups are put together.

Static Solution Culture

Static solution culture is the most most basic form of hydroponics wherein plants are grown in containers such as buckets or Mason jars.

The simplicity of the grow means many setups are homemade with limited equipment. If no oxygen pump is utilised, plants can be suspended slightly above the nutrient solution for access to an oxygen supply.

There can be as many plants in the setup as the reservoir will allow as a hole is cut per plant in the shelf above.

Homemade static solution cultures are be created with plastic tubs or glass jars. If glass jars are used, it’s important to block the light reaching the nutrient solution to minimise algal growth. Light blocking equipment can just be kitchen foil, or baking paper.

Alternatively, a pump system with aquarium tubing and valves will suitably aerate the water sufficiently.

Changing of the nutrient supply is either done at regular intervals or after checking the concentration of the nutrient supply with an electrical conductivity meter.

If plants are suspended above the waterline and the level of the solution drops below where the reach of the roots, water or nutrient solution is added to maintain root access.

A similar setup has the plants sitting on a raft floating on the nutrient solution, removing the issue of a dropping water level.

Nutrient Film Technique

In the nutrient film technique a shallow stream of nutrient solution is passed across a thick bed of roots that develops.

The upper side of the root bed is exposed to the air so plants receive sufficient oxygen for growth. Furthermore, extra oxygen supplies can be added to the nutrient solution with air pumps or air stones.

The concentration of the nutrient solution is adjusted in a primary tank which flows through the plant root matrix and is recirculated again.

To maximise plant growth yield the length and incline of the slope, and the flow rate are precisely measured.

Done correctly, it’s easier to provide plants with an optimal balance of water, nutrients, and oxygen using the nutrient film technique compared to other setups. In others, there is a disparity between the three growth constituents at any one time.

The potential downside of this technique is, for example, if the pump stops working there is no safeguard for the plants to continue receiving their requirements.

Slopes with too much of an incline will pool water at certain points within the root mesh as it can’t flow through the gaps at a fast enough rate. Consequently, a shallower incline will compensate for water buildup and produce a smoother flow.

Flow rates range from 0.5L/min to 2L/min, outside this range may cause nutritional deficiencies for some plants. Similarly, if the length of the channel’s too long there, may be nitrogen depletion. Thus, channel length shouldn’t exceed 10-15 metres unless an additional nutrient supply has been provided halfway down the track.

Passive Sub-irrigation

Passive sub-irrigation is also referred to as semi-hydroponics and uses chemically inactive, porous material to transport nutrient solution via capillary action.

A reservoir holds the nutrient solution which is sucked up via a wick into the chamber holding the inert potting material and plant. Capillary action continues to draw the nutrient solution towards the root system where it’s absorbed.

Maintenance of the setup are relatively easy and cultivating a larger number of plants can be done at reduced labour.

The medium the plants grow in contains a large amount of oxygen available to the root system. Certain species of plant, such as orchids, have exposed roots in their natural environment and increased airspaces helps prevent root rot.

Increased humidity in the system from evaporation means plants preferring drier conditions are less suitable to grow here.

The inert media used can include perlite, vermiculite, and charcoal.

Ebb And Flow

Also known as flood and drain, ebb and flow setups rely on a pumps flooding of the growing medium containing the plants with nutrient solution and allowing it drain out again into the reservoir.

It’s a reliable undertaking and, although usually low in costs, can be intricate in its design. However, it is at the mercy of a pump and if it stops working then there’s no chance the plants can consume the nutrients they require.

Allowing gravity to naturally drain the nutrient solution away by placing the reservoir under the growth medium reduces the reliance on technology without compromising productivity.

The flooding lasts for a short period of time, approximately five to ten minutes. However, this method isn’t popular among commercial hydroponic farmers.

A disadvantage of this setup is that the use of water isn’t as efficient as other methods, with higher likelihoods of root disease seen and regular cleaning of the nutrient solution necessary.

Drip System

The Drip System relies on suspending the plant roots into a oxygenated nutrient solution reservoir as the main plant sits above.

The air pump pumps oxygen through to an air stone which releases bubbles. This highly oxygenated method is favourable as results in fast growth and larger plants.

In Drip Systems, plants are suspended above the waterline and the roots sit in the nutrient solution with air pump and airstone. The water pump sends water from the reservoir directly onto the root system 24/7.

During the first few weeks post-planting, the roots are growing downwards to reach the reservoir. This method means the root system gets a constant supply of oxygenated nutrient solution and is intended to speed up the early growth phase.

Once the plants have grown enough to reach the reservoir they don’t really need anymore assistance, and thus a standard deep water culture setup is sufficient.

You’ve made it this far so we have faith that you’re seriously thinking about giving hydroponics a go.

You know the benefits, you know the terminology, equipment and systems used.

What Do You Grow?

But, what the hell do you grow?

Considerations when deciding include growing something you’re actually going to eat, something expensive so you save that all important cash, or something from lands afar you can’t source easily.

Some of the more simple plants to produce are:

Lettuce

You know that thing Mcdonald's puts in their burgers? No? Oh.

Up there with one of the easiest and best hydroponically grown plants around, it’s a good one to try out if you want to dip your toes in.

The best setup for lettuce is the Nutrient Film Technique.

Cucumbers

You could put your homegrown cucumber in a tuna sandwich or freshen up your glass of water. The possibilities truly are endless.

They need a decent amount of light, make sure you’ve got a good light source. The Drip Technique works best for cucumbers.

Tomatoes

Remember these grow on vines so you may want to include some kind of trellis to support them. Again, tomatoes need a lot of light and, because they’re fruit-bearing, will be a bit more intensive on the hydroponic-growing-scale.

You have nothing to lose. Get growing!

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