There are many technical terms used in marijuana growing, but too many inaccurate definitions of those terms. Our team has almost 70 years of combined cannabis growing experience, so we’ve given you this comprehensive list that you should refer to often…

Aeration: Delivery of fresh air to grow room air, or fresh oxygen to marijuana roots. Also includes moving air around a grow room using fans.

Aeroponics:  A hydroponic growing technology in which marijuana roots are suspended in containers in air, and periodically sprayed with a mist that contains nutrients.

Airstone is a porous stone connected via tube to an air pump and placed in hydroponic reservoirs to add oxygen to nutrients water.

Aquaponics: Combination of aquaculture and hydroponic growing, using fish waste instead of other nutrients.

Autoflowering Marijuana: Selectively manipulated marijuana that starts flowering without photoperiod triggers, usually after about 2-4 weeks in vegetative (grow phase). Needs at least 18 hours of light for its entire life cycle. Does not produce as much harvest weight or THC as a photoperiod plant with similar genetics.

Alkaline: In nutrients water, a pH greater than 7. Alkalinity is a quantitative measurement of the ability of an aqueous solution to neutralize acid.

Backcross: A plant bred with one of its parents to create offspring similar to the original parent. For example, a grower could breed a plant with its own father to make sure the baby has its dad’s height. Backcrossing is often done to maintain rarer strains or strengthen those with desired recessive genes.

Bubble hash—it bubbles when heated sufficiently, and is made by adding bags of marijuana flower to ice water, agitating and freezing. This process breaks off resin glands from the flower, which are then passed through screens several times until an almost crumbly nearly-pure resin material is left.

Beneficial insects and microbes: Organisms including ladybugs, lacewings, and microscopic organisms that feed on, block, or parasitize crop pests. Beneficial microbes are installed in root zone, where they protect & enhance roots. Use of these is often called “biological control.”

Bio solids: Sewage removed during wastewater treatment, sometimes sold as fertilizer.

Bloom Booster: Targeted nutrients, usually phosphorus and/or potassium, meant to enhance floral size and weight.

Bloom Phase: The period of marijuana life cycle when plants are producing flowers.

Branch training: Tying or otherwise guiding marijuana stems and limbs to increase light penetration, widen canopy, control height, increase yield.

CBD (cannabidiol): One of two major cannabinoids, has medical benefits but does not produce a high.

Calcium (Ca): Vital to promoting translocation of carbohydrates, healthy cell wall structure, strong stems, membrane maintenance and root structure development. Calcium is a macronutrient and is often underdelivered in soil & hydroponic growing.

Carbon Dioxide (CO₂) is a colorless, odorless, tasteless gas necessary for plant life. Occurs naturally in the atmosphere at .03%, and the amount is increasing rapidly, leading to climate change.

CO2 generator: A piece of equipment that produces carbon dioxide using natural gas or propane.

Cannabinoids: Compounds such as THC & CBD, and at least a hundred others, uniquely produced by marijuana, and responsible for its highest-impact effects.

Cannabinoid Receptors: Receptors are like locks on cells in your body. Cannabinoids are keys that can ‘unlock’ receptors and cause  physiological responses. The main receptors are CB1 (found mainly in brain) and CB2 (found throughout body).

Marijuana Concentrates: Concentrated cannabinoids made by dissolving marijuana in a solvent. The resulting product has very high THC levels (more than flowers or hashish), and can produce varying products that range from thick sticky oils (BHO) to moldable goo (budder/wax) to hard, brittle, resinous bits (shatter).

Canopy: The uppermost branches and leaves of a marijuana crop.

Carbon dioxide (CO2): A gaseous compound used by plants for photosynthesis, converted to oxygen (O2), water (H2O), and plant biomass.

Chlorosis: Yellowing leaves caused by a nutrient deficiency or poor absorption of nutrients, especially nitrogen.

Chlorine (Cl): Micronutrient is essential for photosynthesis, where it acts as an enzyme activator during the production of oxygen from water.

Clone: A marijuana plant cutting that can be planted and grown, creating a genetic copy of the mother.

Cloning: Creating new plants from cuttings or other pieces of mature plants. The technical term is asexual propagation. Clones are genetically identical to the parent plants, so they will have all the same characteristics.

Closed system: A hydroponic system in which the nutrient solution is continually recycled and then replaced every few days. Nutrient film technique, deep water culture, flood and drain, and aeroponics setups are the most common examples.

Colas: Slang name for large marijuana buds.

Coir: The fiber from the outer husk of coconuts, which can be used as a growing medium for hydroponic plants.

Copper is a micronutrient that acts as an electron carrier and helps with nitrogen fixation.

Cotyledon: the first set of leaves from a germinated marijuana seed. They are not serrated like subsequent leaves are.

Curing happens after the buds are dried when bud moisture and exposure to air is managed to purge chlorophyll and other compounds to create more tolerable smoke and vapor.

Cutting: A piece of leaf and stem that’s been snipped from a mature plant to be replanted and grown into a clone.

Dabs: Concentrated THC, other cannabinoids, and terpenoids usually made with chemical solvents and inhaled as vapor. Very potent, can easily cause marijuana tolerance and addiction.

DLI (Daily Light Integral): The cumulative value of photosynthetic light delivered per square meter per day (rather than per second). DLI and PPFD (Photosynthetic Photon Flux Density) are both ways to measure how much light plants receive. DLI is the daily cumulative of PPFD.

Damping off: A fungal disease that afflicts seedlings and kills them overnight, often with no prior sign of a problem.

Dark Cycle: Photoperiod marijuana during bloom phase needs 12 hours of total darkness each 24 hour period. Even tiny amounts of intrusive light for a few seconds during dark cycle can sabotage marijuana floral development.

Deep-water culture: A hydroponic system in which marijuana roots hang in a solution of nutrient-rich, oxygenated water.

D.O: Dissolved oxygen, the relative amount of oxygen in the water, measured in ppm. Low dissolved oxygen harms roots and plant growth.

Drip System (Drip Emitter System, Drip Irrigation)

A very efficient watering system that employs a reservoir, a main hose, and  small water emitters.

Drying Rack: Usually made of cloth with large pore sizes specifically so marijuana buds can be place in it for drying.

Ebb and flow: A hydroponic system in which plants’ roots are flooded with nutrient solution at regular intervals, and then drained. Also known as a flood and drain.

EC (Electrical Conductivity): It’s the measurement of conductance/conductivity within your hydroponic nutrient solution, representing the concentration of available nutrients in the solution.

Endocannabinoid system is the widespread neuromodulatory system activated by cannabinoids that has massive impact on central nervous system (CNS) development, synaptic plasticity, appetite, mood, stress, immune system, thermomodulation, cognitive performance, emotions.

Entourage Effect: The effects of full-spectrum marijuana including all cannabinoids/terpenoids present in the flower, rather than consuming only THC, CBD, or terpenes.

Evaporative cooling: Process of cooling air by evaporating water, it’s way less efficient than air conditioning.

Evapotranspiration: Water movement and loss  9transpiration) via evaporation of water at the leaf surface.

Feminized seeds: Growers who want to harvest unpollinated buds plant feminized seeds, which have no male chromosomes and therefore never produce pollen. Low quality feminized seeds, however, often produce hermaphrodite clusters and seeds.

Fertigation: Mixing or putting fertilizer into the irrigation water so water and fertilizer are delivered simultaneously as a solution.

Flushing: Giving hydroponic plants only water (rather than a nutrient solution) can wash out excess or imbalanced nutrients. Flushing is a smart strategy whenever plants are ailing, but has been shown NOT to be a smart strategy during the last couple of weeks of bloom phase.

Foliar feeding: Fertilizing plants by spraying a nutrient solution on leaves rather than only feeding through their roots.

Fungicide: A chemical or biological product that can prevent or cure an infection by pathogenic fungi such as root rot.

Geolite (clay pellets) One of several brand names  of clay aggregate medium (also known as LECA or light expanded clay aggregate). It’s lightweight, porous substrate with excellent aeration often used in ebb-and-flow and drip hydroponic systems, or as anchoring material in deep water culture systems.

Germination: The period when a seed is placed into moisture, cracks open, grows a stem and primordial leaves.

Grow Light: Indoor light used for growing marijuana.

Grow Tent: A foldable tent with ports, doors, zippers, hanging bars used as an indoor grow room. Often sold as packages with fans and other gear.

Guano is a potent natural phosphorus, sourced from dung of sea birds or bats.

LED grow light: The most energy efficient, customizable grow light for marijuana, utilizes light emitting diodes. SANLight is the premier brand.

Grow room: An area inside a building used for indoor marijuana growing. Also called “grow op.”

Grow Phase: The first weeks of the marijuana life cycle, from germination until bloom phase. Also called “vegetative phase.”

Hashish: Resin glands by themselves, separated from the rest of the plant.

Hemp: Member of the marijuana genetic line used for thousands of years for its strong fibers, and for its high-nutrition seeds. Hemp contains very low levels of THC, so it’s not used to get high, instead used primarily for CBD extraction.

Heritage (Heirloom) Strains: The early foundational strains of marijuana from 40-60 years ago, such as Northern Lights, Skunk, Haze.  Usually near-landrace or not much hybridized.

Hermaphrodite Marijuana (hermie) is a marijuana floral cluster that has male and female structures that often pollinate themselves, ruining the grower’s quest for seedless buds. Hermie traits are most often the results of inferior breeding and/or excess plant stress.

Hybrid Strain: A marijuana strain produced by interbreeding different types of marijuana. This contrasts with a pure-bred line, which is produced by breeding the same type of marijuana with itself.

Hydroponic growing is a method of cultivation that uses inert media into which nutrients are precisely measured and dosed. The word hydroponics means “working water.”

Hydroponic nutrients are usually synthetic nutrients elements or other chemicals that deliver essential food to marijuana plants.

Hygrometer: An instrument for measuring relative humidity in the atmosphere.

Insecticide: A chemical or natural product used to control insect pests.

Insecticidal soap: Specially formulated fatty acids that cause some types of marijuana pests to dehydrate when they are sprayed with it. Used in part because it’s not poisonous like some insecticides.

Indica Marijuana: Not as accurate a descriptor as years ago before extensive interbreeding, Indica marijuana is generally shorter in height, produces larger buds, and has a more sedating high compared to the other main type of marijuana, Sativa.

IPM (integrated pest management): Uses several complementary methods to fight insect pests, pathogens or plant diseases, rather than relying on only one method, such as only using an insecticide or fungicide. IPM may include both an insecticide and biological control agent. IPM seeks to prevent pathogens, insects, from causing crop losses, using a variety of management methods that are cost effective and as environmentally benign as possible.

Iron (Fe) is a micronutrient catalyst for photosynthesis/respiration, and is essential for the formation of sugars and starches.

Kush is a specific Indica marijuana type originated in the Hindu Kush mountain range in Afghanistan and Pakistan. An Americanized version, OG Kush, has similar lineage. A Kush plant is smaller, stocky, with small hard buds, a unique scent, and sedating effects. Strain names include Hindu Kush, Master Kush, OG Kush, Bubba Kush, Purple Kush.

Landrace marijuana: Marijuana types long adapted to a specific land region, minimally cultivated, sometimes called wild or feral marijuana.

Leaf Curl is a leaf malformation most often caused by overwatering, over-fertilization, magnesium deficiency, insect or fungus damage, or VPD problems.

Leaf Burn occurs when grow lights are delivering too much PPFD and/or are too hot. The leaves start to go pale or brown, tips burn, leaves may curl up, dry up, or die. If caused by grow lights, leaves at top of plant will be the ones affected most.

Limonene: Some marijuana strains contain limonene, a compound that creates the smell of fresh lemons or oranges. Limonene-rich marijuana is often stimulating.

Lollipopping: Cutting lower third of plants’ leaves and branches so plant energy goes into the remaining leaves and flowers. The cut plant shaped like a lollipop. This technique does more harm than good.

Macronutrients: Elements plants must have in large amounts: nitrogen, phosphorus, potassium, calcium, magnesium.

Manicuring: Removing all extraneous leaves and other material from buds so they are compact nuggets of resin glands.

Micronutrients: Essential minerals plants need in small or trace amounts including boron, copper, iron, and zinc.

Mycorrhizae: Soil-dwelling fungi that help roots take up nutrients, they also form hormones and protect roots.

Myrcene is a common marijuana terpenoid also found in mangos, and may smell like mangos. Known for relaxing effects.

Medium (media): The material in which marijuana plants are grown, including soil, coco coir, perlite, Grodan rockwool, peat-based soilless mix, etc. Also referred to as growing media and substrates.

Meters: Devices used to measure alkalinity of water (pH meters), the amount of solids in water (EC, TDS, PPM meters) and the total amount of beneficial radiation reaching plants (PPFD) meters.

Motherplant: A favorite adult female marijuana plant perpetually kept in grow phase to cuttings can be taken from it to make clones.

Necrosis is seen when leaves turn gray, brown or die dying, usually due to insufficient or imbalanced nutrients.

Neem oil: An oil pressed from the seeds of the neem tree (Azadirachta indica), an evergreen tree native to India. It’s a relatively safe insecticide and fungicide, but it gums up leaves and doesn’t work very well.

Nitrogen (N) is crucial to marijuana growth, especially in early life. It promotes formation of stalks, stems, leaves, buds, seeds, and chlorophyll.

NFT (Nutrient Film Technique) is hydroponic system in which nutrient is fed into grow tubes or trays in a thin film from which roots draw nutrients. This “nutrient film” allows roots to have constant contact with the nutrient and the air layer above at the same time.

N-P-K ratio: The ratio of the primary nutrients nitrogen (N), phosphorus (P), and potassium (K).

Nute burn: A condition that occurs when plants are overfed; most revealed by yellow leaf tips.

Nutes: Slang for liquid fertilizer or nutrients.

Nutrient solution: The blend of fertilizer and water used to feed and hydrate marijuana.

Organic Fertilizers (Nutrients): Marijuana feeding materials derived from raw nature rather than chemistry, using materials such as bone meal, blood meal, bat guano, humic and fulvic acid, etc. Not as precise or reliable as hydroponic nutrients, and sometimes contaminated with heavy metals or pathogens.

Pathogens: Organisms such as bacteria, viruses, molds, or fungi that cause plant diseases

pH: Measurement oh how acidic or basic (alkaline) a solution is. A pH less than 7 is acidic. A pH more than 7 is basic. A pH of 7 is neutral. In almost all marijuana growing situations, nutrients water pH should be between 5.7-6.3.

Phenotype refers to a uniform suite of physical traits such as height, branch structure, color, etc.

Photons: Tiny particles of light energy in the PAR range. Photons are converted into useful energy by plants through the photosynthetic process. Different photons have different wavelengths—a blue photon has a short wavelength, and a red photon has a longer wavelength. Photons are measured in micromoles.

Phosphorus (P) is a crucial macronutrient necessary for early growth, root health, and bud development. 

Photoperiod: The amount of time a plant is exposed to light in a 24 hour day, tightly controlled by indoor growers.

Photoperiod Marijuana: As differentiated from autoflowering marijuana, photoperiod marijuana acutely responds to photoperiod with 18 hours per day of light given in the first weeks of plant life, then 12 hours per day for bloom phase.

PAR (Photosynthetically Active Radiation): Radioactive energy that stimulates photosynthesis and other plant metabolic functions.

PPFD (Photosynthetic Photon Flux Density): PPFD measures the amount of photosynthetically active radiation per surface area. Technically, it’s micromoles per square metre per second (µMol/m2/S) which precisely describes how many PAR photons land on a specific area. PPFD can only be measured by a specialty meter made by the American company Apogee.

PPM (Parts per Million). Concentration unit of a nutrient, oxygen, or chemical in water.

Perlite is sand or volcanic glass expanded by heat into small white chunks that hold water and nutrients. It’s an inert substance and the coarse grade is the most useful.

Pinene is a marijuana terpenoid also present in pine trees; it reduces inflammation and assists the respiratory system.

Pistils are hair-like structures on buds that start out white but often change to orange, red, or pink in color as buds mature, found only on female plants.

Potassium (K) is a macronutrient necessary for bud production, disease resistance, formation of carbohydrates, starches and sugars.

Potassium silicate: The right form of silicon, which is a strengthener building block for plant tissues, including resin glands. Can be used as a root feed or foliar feed.

Pyrethrin: A compound found in chrysanthemums used as natural insecticide.

Relative humidity:  The amount of water in the air divided by the amount of water the air can hold if saturated, at a given temperature.

Reservoir: Storage container in hydroponic system from which nutrient solution is delivered to plants.

Resin glands are tiny structures on marijuana flowers where the majority of cannabinoids and terpenoids are made.

Reverse Osmosis is a filtration process that removes all materials from water to get close to zero parts per million.

Rock wool (rockwool): A popular growing medium for hydroponic growers, made from melting rock and extruding it into threads. The most reliable brand of rockwool is Grodan.

Rooting Hormone (Cloning Powder or Liquid): Hormone compound used to coat the ends of cuttings before placement in media to promote root growth.

Ruderalis Marijuana is hempy, low-cannabinoids, resilient, often used as a genetic tool to create autoflowering marijuana.

Run to Waste is a fertigation system in which nutrient solution runs out of pots and is drained away rather than into a reservoir for reuse.

Sativa Marijuana generally grows out as taller plants with thinner leaves than Indica marijuana, producing longer, thinner buds and taking longer to mature in bloom phase. Sativa has a more stimulating, creative, less-relaxing high compared to Indica.

SCROG (Screen of Green): A marijuana cultivation method that puts a screen trellis horizontally across the plant canopy. Plants grow into and through it, providing branch support.

Sea of Green: A cultivation method in which small, usually single-cola clones are placed close together to maximize floor space by increasing canopy density.

Sexual Propagation produces seeds by breeding male and female plants.

Solvent Extracts: Made using harsh chemicals such as alcohol and butane, solvent extracts are ultra-pure cannabinoid products, but may be too strong, and often contain harmful traces of toxic solvent.

Strain: Marijuana plants that carry the same unique characteristics  in vigor, aroma, flavor, growth patterns, psychoactive effects, yield, potency. Also called “Cultivar.”

Substrate: Material in which plants are grown, such as soil, coco coir, perlite, rockwool, etc. Also referred to as growing medium (media).

Temperature: A measure of the amount of heat in the air or on a surface.

Terpenoids (terpenes): Produced in marijuana resin glands, these non-cannabinoid compounds have minor psychoactive/medical effects, and also account for most marijuana taste and scent.

THC (Tetrahydrocannabinol), the primary psychoactive compound marijuana produces, responsible for its recreational effects.

Tolerance: As you consume marijuana, your body habituates to it, making it necessary to consume more to get the same intensity of effects.

Topping: Cutting off the apical meristem (topmost stem part) in grow phase to create a stockier plant with more horizontal branching.

Total Dissolved Solids (TDS) is a measure of parts per million (PPM) showing the amount of minerals dissolved within nutrient water.

Trichome: Glandular structures on marijuana flowers that produce majority of THC and other cannabinoids and terpenoids.

Triploid Marijuana is a new genetic marijuana variation created by Humboldt Seed Company that uses genetic manipulation to make plants that are sterile, all-female, stronger, and produce more potent buds.

Vape/Vaporizer: The safest way to inhale marijuana is not combustion, but through a vaporizer. The world’s best vaporizers are made by Germany’s own Storz & Bickel.

Vapor pressure deficit (VPD) is measure of air’s moisture content as it relates to plant transpiration. VPD is the difference between the actual water vapor pressure of air and the water vapor pressure possible at saturation for a particular temperature. At low VPD, transpiration may be too low due to the high moisture content in the air. At high VPD, a plant’s transpiration rate may be too high.

Ventilation: The process of bringing in fresh air and purging stale air from a gardening space.

Yield: The total weight of dried buds from a plant.