Hydroponics Glossary: A Comprehensive Guide to Must-Know Terms for Growers

Hydroponics Glossary A to Z

Welcome to the ultimate hydroponics glossary, your one-stop resource for all things related to hydroponic gardening. Whether you’re a beginner looking to start your own hydroponic garden or an experienced grower wanting to expand your knowledge, this extensive list of terms will provide you with a comprehensive understanding of hydroponics.



The process of increasing air circulation and oxygen levels in the hydroponic nutrient solution. Important for healthy root growth.


A hydroponic method where plants are suspended with their roots exposed to an air/mist environment. Nutrient solution is misted onto the roots frequently using spray nozzles or misters. Allows more oxygen to reach the roots.

Aggregate culture

Aggregate culture is a hydroponic technique where plants are grown in an inert porous medium such as clay pebbles, gravel, perlite, vermiculite, rockwool etc. The medium provides support while the plant roots receive nutrients from the hydroponic solution. Allows for good drainage and aeration.

Air lift pump

An air lift pump is a pump that uses air bubbles to lift nutrient solution up to the plant roots. It has no moving parts.

Air pump

An air pump is used to oxygenate the nutrient solution by pumping air through air stones or other diffusers, creating bubbles. Important for providing oxygen to roots and preventing diseases. Multiple air pumps may be needed for larger systems.

Air stone

An air stone is a porous stone connected to an air pump that releases air bubbles into the hydroponic system. It breaks up the air into small bubbles to maximize surface contact with the water.

Algal bloom

An rapid increase in algae growth that can block light and oxygen from reaching plant roots. Can be prevented with UV sterilizers.


Alkaline refers to a substance or solution with a pH level greater than 7 on the pH scale. Alkaline solutions are characterized by their basic or non-acidic nature. In gardening and hydroponics, maintaining proper pH levels is crucial, as some plants prefer slightly alkaline conditions in their root zone. Alkaline substances can be used to adjust and raise the pH of acidic soils or nutrient solutions to create a more suitable environment for certain plants to thrive.


A soilless system combining hydroponics with aquaculture, where fish waste provides nutrients for plant growth.


An U-shaped device used in ebb & flow systems to control the flood and drain cycles automatically.


Batch system

A type of hydroponic system where plants are grown in individual containers of nutrient solution. The batches are dumped and replaced with fresh solution periodically.

Bato bucket

A bato bucket is a hydroponic bucket system using a bucket-within-a-bucket to house the nutrient solution and aggregate medium separately.

Bell siphon

A bell siphon is a passive drainage device used in ebb & flow systems and flood tables to automatically trigger the drain phase. As the water level rises, it fills the bell and creates a siphon to rapidly drain the tank. No power required.

Blunder bucket

A blunder bucket is a simple deep water culture system using a plastic bucket and air stone.

Bubbler bucket

A bubbler bucket is a hydroponic bucket system where an air stone aerates the nutrient solution.


Channel system

A channel system consists of hydroponic channels that contain flowing nutrient solution for plant roots to absorb.

CHC Controller

A CHC (climate-humidity controller) is used to automatically regulate fans, ventilation, lighting etc. in indoor hydroponics.

Clay pebbles

Clay pebbles are small round porous clay aggregates, baked at high temperatures to create an inert growing medium. Allow good drainage and air pockets for healthy hydroponic root growth. Come in various sizes from 4mm to 16mm.

Clay pellets

Small clay pebbles used as an aggregate medium in hydroponics. Provide support while draining well.


Cloning in hydroponics is a technique used to replicate desirable plant traits by creating genetically identical copies, or clones, of a parent plant. This is achieved by taking cuttings from the parent plant, encouraging them to develop roots, and then transplanting them into the hydroponic system for further growth. Cloning allows hydroponic growers to maintain consistency in crop characteristics, such as yield and disease resistance, while reducing the reliance on seeds.

Coco Coir

A growing medium made from the fibrous husk of coconuts, often used in hydroponics due to its excellent water retention and aeration properties.

Constant flow technique

The constant flow technique is a hydroponic method where the nutrient solution constantly flows through growing channels or tubes past the roots before draining away. Ensures roots have constant access to fresh oxygenated solution.


A cutting is a vegetative propagation technique in which a portion of a parent plant, typically a stem or leaf, is removed and then placed in a suitable growing medium to develop into a new plant. Cuttings can be taken from a variety of plants and are a common method for cloning desirable characteristics, such as disease resistance or specific traits, from one plant to another. This method allows for the replication of plants without relying on seeds, often resulting in genetically identical offspring to the parent plant.


Deep flow technique

The deep flow technique is a hydroponic technique where roots are fully submerged in an aerated nutrient solution.

Deep water culture (DWC)

Deep water culture is a hydroponic technique where plant roots are fully submerged in a nutrient solution reservoir, with air pumped in to oxygenate the solution. Plants sit in inert medium filled pots on polystyrene.


Dolomite is added to hydroponic systems to stabilize pH and provide calcium and magnesium.

Drip emitter

A drip emitter is the small nozzle on drip irrigation systems that delivers nutrient solution drip-by-drip to plants.

Drip irrigation

Drip irrigation is a hydroponic method where nutrient solution is delivered directly to the root zone of each plant through emitters and drip lines. Drippers provide slow, measured flow to each site. Allows better control than top feeding or flood methods.

Dutch bucket

A Dutch bucket is a type of hydroponic system using 10-15L plastic buckets filled with clay pebbles or other aggregate medium. A drip line runs down into the medium from the bucket lid to deliver nutrients.


Ebb & flow

Ebb & flow is a hydroponic technique of periodically flooding then draining out nutrient solution in grow trays.

Expanded clay

Expanded clay is porous clay pebbles that have been baked and expanded at high heat. One of the most common aggregate media for hydroponics. Provide aeration and drainage while wicking up moisture. Come in various sizes.



A substance or mixture containing essential nutrients that are applied to soil or hydroponic systems to promote plant growth and enhance crop yields. Fertilizers provide plants with macronutrients (e.g., nitrogen, phosphorus, potassium) and micronutrients (e.g., iron, zinc) necessary for their development.

Flood table

A flood table is a hydroponic system where plants sit in a lidded tray that is flooded from beneath intermittently.

Floating raft

A floating raft system uses polystyrene rafts floating on nutrient solution with plant roots suspended beneath.


A type of microorganism that belongs to the kingdom Fungi. Fungi can be beneficial or harmful to plants and ecosystems. Beneficial fungi, such as mycorrhizae, form symbiotic relationships with plants, enhancing nutrient uptake. Harmful fungi can cause diseases and infections in plants, leading to various plant health issues.


A chemical or biological substance specifically designed to control, prevent, or eliminate fungal diseases in plants. Fungicides are used to protect crops from fungal infections that can reduce yield and quality. They work by inhibiting fungal growth or disrupting their reproductive processes.


Grow lights

Grow lights are artificial lighting optimized for plant growth, used in indoor hydroponics.


Hard water

Hard water contains minerals that can clog hydroponic systems. Must be filtered.

Horticultural Charcoal

Horticultural charcoal, or activated charcoal, is used in gardening to improve soil drainage, reduce odors, enhance nutrient retention, and promote beneficial microbial activity. It helps maintain a healthy growing environment, especially in container gardening and terrariums.

Hydrion paper

Hydrion paper, also called litmus paper, is special pH indicator paper used to test pH levels in hydroponic solutions. Paper changes color according to the pH range when dipped in the solution. More accurate than standard pH pens for small volumes.


Hydrocorn consists of pellets made from baked clay used as growing media in hydroponics. Provide aeration.

Hydroponic media

The different types of aggregate materials like rockwool, perlite, clay pellets etc. that support plants and roots in certain hydroponic systems.

Hydroponic nutrient

Special nutrient solutions formulated to provide all the elements plants need in the correct proportions for hydroponics.

Hydroponic Pest Control

Methods and products used to manage and prevent pest infestations in hydroponic gardens without using soil.

Hydroponic Reservoir Management

The practice of monitoring and maintaining nutrient levels, pH, and temperature in the nutrient reservoir to ensure plant health.

Hydroponic System Types

Various setups and configurations, such as drip systems, aeroponics, and vertical farms, used in hydroponics to grow plants.


Hydroton is a brand name for expanded clay growing media. It is porous for drainage.


An enzyme solution that helps break down dead roots and other organic matter that can clog hydroponic systems.



Infusoria are single celled organisms that colonize root systems and help provide nutrients. Can be added to hydroponic systems intentionally.


Kratky Method

The Kratky Method is a passive hydroponic growing technique developed by Dr. Bernard Kratky. In this method, plants are grown in containers with a static nutrient solution level, allowing the plant roots to passively absorb water and nutrients as they grow. Unlike traditional active hydroponic systems that use pumps and a continuously flowing nutrient solution, the Kratky Method relies on the initial nutrient solution level to sustain the plants throughout their growth cycle. As the plant consumes water and nutrients, the solution level gradually decreases. This method is particularly suitable for low-maintenance crops like lettuce and other leafy greens. The simplicity and efficiency of the Kratky Method make it a popular choice for home gardeners and small-scale hydroponic setups.



LPM stands for liters per minute. It is the unit of measurement for pump flow rate.



A mister is a high pressure spray nozzle used in aeroponic systems to mist nutrient solution onto the plant roots frequently, while they hang suspended in an air chamber. Provides excellent oxygenation.


Net pot

A net pot is a plastic pot or basket made from mesh or netting designed for hydroponics. Allows roots to access the nutrient solution while providing support with an aggregate medium like clay pebbles.

NFT (Nutrient Film Technique)

NFT stands for Nutrient Film Technique. It is a hydroponic method where nutrient solution flows through shallow channels. Plant roots dangle into the thin film of solution, absorbing nutrients as it flows by. Requires precise control of flow rate and pH.


Nitrogen (N) is a vital macronutrient essential for plant growth and development. It is a key component of amino acids, proteins, and chlorophyll, all of which play crucial roles in plant processes. Nitrogen is necessary for leafy green growth, overall plant vigor, and the formation of DNA. In soil-based and hydroponic cultivation, nitrogen is often provided to plants through fertilizers in various forms, such as ammonium nitrate, urea, or nitrate-based compounds. Proper nitrogen management is important to prevent nutrient imbalances and promote healthy plant growth.


N-P-K stands for Nitrogen (N), Phosphorus (P), and Potassium (K), which are the three primary macronutrients essential for plant growth. These elements are commonly represented in the form of a three-number ratio on fertilizer labels, such as 10-20-10 or 20-10-10. Each number in the ratio represents the percentage by weight of the respective nutrient in the fertilizer.

  1. Nitrogen (N): Nitrogen is essential for promoting leafy green growth, overall plant vigor, and the formation of amino acids, proteins, and chlorophyll. It is crucial for photosynthesis and the production of enzymes.
  2. Phosphorus (P): Phosphorus plays a pivotal role in root development, flowering, and fruiting. It is vital for energy transfer, DNA and RNA synthesis, and cell division.
  3. Potassium (K): Potassium is important for maintaining osmotic pressure within plant cells, enhancing disease resistance, and regulating water and nutrient movement within the plant. It contributes to overall plant health and stress tolerance.

The N-P-K ratio on a fertilizer label helps growers choose the right fertilizer formulation to meet the specific nutrient needs of their plants at different growth stages.

Nutrient burn

Nutrient burn is leaf scorching from an excessive buildup of nutrients. Can result from using too strong of nutrient solutions.

Nutrient Solution

A liquid mixture consisting of water and dissolved essential nutrients, including macronutrients (e.g., nitrogen, phosphorus, potassium) and micronutrients (e.g., iron, zinc), specifically formulated to provide plants with the necessary elements for growth. Nutrient solutions are a fundamental component of hydroponic systems and are carefully balanced to ensure that plants receive the appropriate nutrients required for healthy development. The pH and electrical conductivity (EC) of the nutrient solution are often monitored and adjusted to maintain optimal conditions for plant growth.


Oasis cube

Oasis cubes are spongy foam cubes used to start seedlings in hydroponics before transplanting.


Oxygenation is the process of adding oxygen to hydroponic systems, vital for healthy roots. Usually done by air pumps and stones.



Perlite consists of small white granules made from volcanic glass. Used as an aggregate medium in hydroponics for drainage and aeration.

pH Buffer

Substances added to the nutrient solution to stabilize pH levels and prevent drastic fluctuations.

pH meter

A pH meter is an electronic device used to accurately measure the pH of hydroponic nutrient solutions. More accurate than paper methods. Requires periodic calibration and cleaning. Measures pH digitally.


Phosphorus (P) is an essential macronutrient required for plant growth and development. It plays a crucial role in various physiological processes, including energy transfer, DNA and RNA synthesis, and cell division. Phosphorus is particularly important for root development, flowering, and fruiting in plants. In agriculture and horticulture, phosphorus is supplied to plants through fertilizers in various forms, such as phosphates. Proper phosphorus management is vital for ensuring healthy plant growth and optimizing crop yields.


Photoperiod refers to the duration of time each day during which a plant is exposed to light, particularly natural sunlight or artificial light sources such as grow lights. It plays a crucial role in regulating various plant processes, including flowering, vegetative growth, and dormancy. Different plant species have specific photoperiod requirements, which influence their growth and development patterns. Some plants are classified as short-day plants, requiring shorter periods of light to induce flowering, while others are long-day plants, requiring longer light exposure. Photoperiod manipulation is a technique often used in controlled environments like greenhouses and indoor cultivation to optimize plant growth, flowering, and fruiting.


Photosynthesis is the vital biological process by which green plants, algae, and certain bacteria convert light energy, typically from the sun, into chemical energy stored in the form of glucose (sugar). This process occurs in chloroplasts, which contain the pigment chlorophyll, and involves the absorption of carbon dioxide (CO2) and water (H2O). During photosynthesis, these substances are transformed into glucose and oxygen (O2) through a series of complex biochemical reactions. The glucose serves as a primary energy source for the plant, while the released oxygen is released into the atmosphere, benefiting all aerobic organisms. Photosynthesis is fundamental to the survival of plants and is a crucial component of the Earth’s carbon cycle.


Pollen is a fine, powdery substance produced by the male reproductive structures (anthers) of flowering plants. It contains the male gametes (sperm cells) necessary for fertilizing the female reproductive structures (ovules) to produce seeds. In natural environments, pollen is transferred from the anthers to the stigma (female part) of the same or another flower through pollination, typically aided by wind, insects, birds, or other agents. In hydroponics and controlled indoor growing environments, artificial pollination methods may be employed to ensure the fertilization of plants, especially in cases where pollinators are absent.

Pond liner

Pond liners are EPDM rubber liners used to create hydroponic reservoirs that hold nutrient solutions.


Potassium (K) is a critical macronutrient essential for plant growth and development. It plays a pivotal role in various physiological processes within plants, including enzyme activation, osmoregulation, and the transportation of nutrients and water within plant tissues. Potassium is particularly important for improving a plant’s resistance to environmental stressors, such as drought and diseases, and for enhancing fruit quality. In agriculture and horticulture, potassium is supplied to plants through fertilizers in various forms, such as potassium chloride (KCl) and potassium sulfate (K2SO4). Proper potassium management is essential for ensuring robust plant growth and optimizing crop yield.

PPM (Parts Per Million)

PPM, or parts per million, is a unit of measurement used to express the concentration of one substance within a larger mixture. In hydroponics and agriculture, PPM is commonly used to measure the concentration of dissolved substances, such as nutrients, minerals, or salts, in a solution, including water or nutrient solutions. It indicates the number of units of a particular substance present in a million units of the solution. PPM is a critical metric for growers to monitor and control nutrient levels, ensuring that plants receive the appropriate concentration of essential elements for optimal growth. In hydroponic systems, the PPM of nutrient solutions is regularly measured and adjusted to maintain the desired nutrient strength for plant health and productivity.


Trimming back plant foliage to redirect growth and maximize fruit yields.

PVC pipes

PVC pipes are polyvinyl chloride plastic piping used for constructing hydroponic systems. PVC allows smooth water flow, is inert, inexpensive and easy to install. Main downside is that it can become brittle with prolonged UV exposure.


A fungal root rot disease that commonly infects overwatered hydroponic systems.


Recirculating system

A recirculating system is a hydroponic system where the unused nutrient solution is collected, reconditioned and reused for multiple cycles. Much more efficient than drain-to-waste since water and nutrients are not constantly discarded.


A reservoir is the tank that holds the nutrient solution in certain hydroponic system designs.


Rockwool is a fibrous growing medium made from molten basalt rock and chalk spun into insulation. Used in hydroponics. Provides excellent drainage and air pockets for roots while retaining moisture and nutrients.

Root rot

A fungal disease that causes roots to turn brown and die. Usually caused by lack of oxygen from inadequate water aeration.

Root Zone

The area where plant roots are located, often the focus of nutrient delivery and oxygenation in hydroponic systems.

Run to waste

In run to waste hydroponic systems, the nutrient solution flows through once before being discarded. Requires more nutrients and water than recirculating systems.



Scrog stands for “screen of green”. It involves using a mesh to train and spread out plant branches in hydroponics.

Secondary Nutrients

Secondary nutrients are essential elements required for plant growth, but they are needed in smaller quantities compared to primary macronutrients (nitrogen, phosphorus, and potassium). The secondary nutrients include:

  1. Calcium (Ca): Calcium plays a vital role in cell wall structure, membrane integrity, and cell division. It also helps neutralize acidic soils and improve soil structure.
  2. Magnesium (Mg): Magnesium is a component of chlorophyll, the green pigment essential for photosynthesis. It is crucial for energy transfer within the plant and the activation of various enzymes.
  3. Sulfur (S): Sulfur is necessary for the formation of amino acids, vitamins, and enzymes. It plays a role in the synthesis of proteins and helps improve crop quality.

While secondary nutrients are required in smaller quantities than primary macronutrients, they are still essential for healthy plant growth. Proper nutrient management, which includes supplying secondary nutrients as needed, ensures that plants receive a balanced diet of essential elements for optimal development.

Sub irrigation

Sub irrigation involves delivering nutrients directly to plant roots from underneath using platforms or other devices.


The substrate is the medium used in hydroponics to support plants and roots. Common substrates include rockwool, perlite, clay pebbles etc.


TDS meter

A TDS meter is a device used to measure total dissolved solids (nutrients) in a hydroponic reservoir.

Top feed system

A hydroponic method where the nutrient solution is delivered from above and flows down through the aggregate media to the plant roots.


The evaporation of water from plant leaves, which draws up moisture and nutrients from the roots.


The process of moving seedlings or young plants from one container to another in a hydroponic system, typically when they outgrow their initial containers.



Vermiculite is a lightweight mineral used in gardening and hydroponics. It improves soil aeration, retains moisture, and provides a suitable medium for seed germination and root growth.

Vertical Farming

A hydroponic method that utilizes stacked trays or shelves to maximize space and grow crops in a vertical arrangement.


Wall Gardening

Wall gardening, also known as vertical gardening, is a method of growing plants vertically on walls, fences, or other vertical surfaces. In wall gardening, plants are planted in containers, pockets, or specialized vertical planters attached to vertical structures. This innovative gardening approach maximizes space utilization and is particularly useful in urban environments, small gardens, or areas with limited horizontal space. Wall gardening allows for the cultivation of a variety of plants, including flowers, herbs, vegetables, and even succulents, creating green and visually appealing vertical gardens. It offers benefits such as efficient use of space, improved aesthetics, and better accessibility for maintenance and harvesting. Wall gardening is a versatile and creative solution for both decorative and functional gardening in constrained spaces.

Water pump

Pump used to deliver water and nutrient solution in certain hydroponic systems like NFT and aeroponics.

Wick System

A passive hydroponic system where a wick draws nutrient solution from a reservoir to the plant’s root zone.

Hydroponics Glossary: A Comprehensive Guide
Hydroponics Glossary: A Comprehensive Guide to Must-Know Terms for Growers
Hydroponics Glossary: A Comprehensive Guide to Must-Know Terms for Growers

About Jeremiah Holegrape

Jeremiah Holegrape
My name is Jeremiah Holegrape and I'm an enthusiastic hobby hydroponic gardener. I've been passionate about hydroponics for several years now, and I love experimenting with different plants and growing techniques. What fascinates me most about hydroponics is the incredible efficiency and flexibility it offers. With hydroponics, I can grow a wide variety of plants in a small space, using minimal water and nutrients. I'm constantly amazed by the speed and quality of growth that hydroponic systems can achieve, and I love the fact that I can control every aspect of the growing environment to achieve the best possible results.

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