Cannabis Growing Glossary

Definition: A plant that stays in vegetative growth based on day length and starts flowering when nights become long enough.

• Why it matters: You can control plant size and timing indoors by changing the light schedule. Outdoors, planting date and seasonal day length matter.
• Common confusion: Photoperiod is not indica or sativa. It only describes the plant’s response to light.
• Related: Vegetative stage, Flowering, Light cycle

Definition: A plant that flowers based on age, not day length.

• Why it matters: Easier for beginners and outdoor growers because you do not need to control light timing. The tradeoff is a fixed lifespan, so early mistakes can cost yield.
• Common confusion: You cannot keep an autoflower in veg longer by changing lighting.
• Related: Vegetative stage, Flowering

Definition: Seeds bred to produce female plants in almost all cases.

• Why it matters: Female plants produce the flowers most growers want. Feminized seed reduces the risk of accidentally growing males.
• Common confusion: Feminized does not mean “guaranteed,” and stress can still cause rare issues in some genetics.
• Related: Sexing, Hermaphrodite

Definition: Seeds that can produce either male or female plants.

• Why it matters: Regular seeds are essential for breeding and pheno hunting. They require you to identify and remove males if you are growing for flower.
• Related: Sexing, Pollination

Definition: The way a plant actually expresses its genetics, what you can see, smell, and measure.

• Why it matters: Even seeds from the same pack can look and perform differently. Selecting the best phenotype is how breeders and growers find standout plants.
• Common confusion: Two plants can have the same parents but still express different traits.
• Related: Genotype, Cultivar

Definition: The plant’s genetic blueprint, what it is capable of expressing.

• Why it matters: Environment can change how traits show up, but it cannot create traits that are not present in the genetics.
• Related: Phenotype

Definition: A cultivated variety, basically a named genetic line people grow on purpose.

• Why it matters: Different cultivars have different feeding needs, growth patterns, and resistance to stress or pests.
• Common confusion: “Strain” is common slang. “Cultivar” is the more accurate grower term.
• Related: Phenotype

Definition: Aromatic compounds that drive smell and flavor.

• Why it matters: Terpenes are strongly influenced by genetics, but environment, drying, and curing can preserve or destroy them.
• Related: Dry and cure

Definition: Identifying whether a plant is male or female.

• Why it matters: Males release pollen, which can seed your crop and reduce flower quality for most growers.
• Related: Regular seeds, Pollination

Definition: A plant that produces both female flowers and some male pollen sacs.

• Why it matters: It can self-pollinate or pollinate nearby plants, leading to seeds in buds.
• Common confusion: Some herms are genetic, others are stress-driven (light leaks, heat spikes, severe swings).
• Related: Stress, Light leak

Definition: When pollen reaches a female flower and triggers seed production.

• Why it matters: Seeded flowers usually have lower bag appeal and potency compared to sensimilla (seedless flower).
• Related: Sexing, Hermaphrodite

Definition: A measure of how much usable plant light hits a specific area each second.

• Why it matters: Too low and growth is slow. Too high and plants can bleach, stress, or demand more water and nutrients than you can supply.
• Easy version: PPFD is “light intensity where the plant is sitting.”
• Related: DLI, Light distance

Definition: The total amount of usable light a plant receives in a day.

• Why it matters: DLI combines intensity (PPFD) and time (hours). It helps you stop guessing about “enough light.”
• Easy version: PPFD is the speed. DLI is the total distance traveled in a day.
• Related: PPFD, Light cycle

Definition: How many hours per day the lights are on and off.

• Why it matters: Photoperiod plants use light cycle changes to trigger flowering. Autoflowers do not, but still respond to overall light amount.
• Related: Photoperiod, Autoflower

Definition: A way to describe how “thirsty” the air is, based on temperature and humidity.

• Why it matters: If the air is too dry, plants transpire too fast and can stress. If it is too humid, transpiration slows and plants can struggle to move nutrients.
• Easy version: VPD is the tug-of-war between the plant and the air.
• Related: Transpiration, RH

Definition: How much moisture is in the air compared to how much the air could hold at that temperature.

• Why it matters: RH affects transpiration, disease pressure, and how comfortable your plants are.
• Related: VPD

Definition: Movement of air through and around the canopy.

• Why it matters: Good airflow helps prevent mold, strengthens stems, and reduces hot or humid pockets.
• Related: Canopy, Powdery mildew

Definition: Unwanted light during the plant’s dark period.

• Why it matters: Photoperiod plants can get stressed or confused during flower, increasing the risk of herms or reduced quality.
• Related: Photoperiod, Hermaphrodite

Definition: Anything that pushes the plant out of its comfort zone, like heat spikes, overwatering, severe dryness, or big feeding swings.

• Why it matters: Stress slows growth and can trigger herms in sensitive genetics.
• Easy version: Stress is when the plant spends energy surviving instead of growing.

Definition: The material roots grow in, like soil, coco, peat, or rockwool.

• Why it matters: Your medium determines how often you water, how nutrients behave, and how forgiving mistakes will be.
• Related: Soil, Coco

Definition: A living or semi-living mix that can hold nutrients and buffer pH changes.

• Why it matters: Soil tends to be more forgiving. Biology helps manage nutrient timing and availability.
• Related: Living soil, Top dress

Definition: Soil managed to support active microbes and a healthy food web that helps feed the plant.

• Why it matters: When biology is healthy, nutrient availability becomes steadier and the plant can be more resilient.
• Common confusion: Living soil is not “no work.” It just shifts the work toward watering consistency and soil stewardship.
• Related: Microbes, Compost tea

Definition: A soilless medium made from coconut husk fiber.

• Why it matters: Coco drains well and provides lots of oxygen to roots, but it behaves more like hydroponics, meaning consistent feeding and runoff management matter.
• Related: EC, Runoff

Definition: The minerals a plant needs to build tissue and run basic functions, like nitrogen, calcium, and potassium.

• Why it matters: Too little slows growth. Too much can burn roots or lock out other nutrients.
• Easy version: Nutrients are the building materials. The plant still needs good light and environment to use them.
• Related: EC, pH

Definition: A measurement that estimates how strong your nutrient solution is.

• Why it matters: EC helps you avoid overfeeding and underfeeding. It is one of the simplest “truth checks” in salt based growing and coco.
• Common confusion: EC does not tell you which nutrients are present, only the overall concentration.
• Related: PPM, Nutrients

Definition: Another way of expressing nutrient strength, often shown on meters as a conversion from EC.

• Why it matters: Many feeding charts use PPM. The issue is there are different PPM scales, so EC is often clearer.
• Related: EC

Definition: A measure of how acidic or basic a solution is.

• Why it matters: pH affects what nutrients the plant can actually absorb. If pH is off, you can have nutrients present but unavailable.
• Easy version: pH is the “doorway” for nutrient uptake.
• Related: Nutrient lockout

Definition: Water that drains out the bottom of the container after watering.

• Why it matters: In coco and salt based growing, runoff helps prevent salt buildup and can be measured to spot problems early.
• Related: EC, Salt buildup

Definition: Adding dry amendments or compost to the top of the soil surface so watering carries it down over time.

• Why it matters: Top dressing is a simple way to replenish nutrients in organic systems without mixing new soil.
• Related: Soil, Living soil

Definition: When the plant cannot absorb nutrients that are present, usually because pH is off or salts are out of balance.

• Why it matters: Lockout can look like a deficiency even though you are feeding plenty. Fixing the root cause matters more than adding more fertilizer.
• Related: pH, Salt buildup

Definition: When fertilizer salts accumulate in the root zone over time.

• Why it matters: Salt buildup can cause tip burn, lockout, and stressed roots. Managing runoff and consistent feeding prevents it.
• Related: Runoff, EC

Definition: Beneficial bacteria and fungi that live in the root zone and help cycle nutrients.

• Why it matters: In organic systems, microbes help convert amendments into forms the plant can use and can improve resilience.
• Related: Living soil, Compost tea

Definition: A brewed liquid made from compost and inputs, used to introduce or feed microbes.

• Why it matters: It can be helpful when done correctly, but it is not required for success. Poorly made tea can create problems.
• Easy version: Compost tea is “microbe support,” not a magic potion.
• Related: Microbes

Definition: The growth stage where the plant builds stems and leaves and increases in size.

• Why it matters: Most training happens here. Healthy veg sets the foundation for flower.
• Related: Flowering, Canopy

Definition: The stage when the plant produces flowers (buds).

• Why it matters: This stage is less forgiving of major changes. Consistency with environment and watering becomes even more important.
• Related: Photoperiod, Light leak

Definition: The period early in flowering when plants grow rapidly in height.

• Why it matters: If your canopy is not managed before stretch, plants can outgrow the space fast and create airflow problems.
• Related: Canopy, Trellis

Definition: The top layer of the plant, where most leaves and bud sites receive light.

• Why it matters: An even canopy helps distribute light evenly, improving overall quality and reducing weak lower growth.
• Related: Lollipopping, Defoliation

Definition: Removing some leaves to improve airflow and light penetration.

• Why it matters: Done lightly, it can reduce humidity pockets and help the canopy perform. Done aggressively, it can stress plants and slow growth.
• Easy version: Remove what blocks airflow and light, not everything you can reach.
• Related: Airflow, Stress

Definition: Removing lower branches and growth that will never receive enough light to produce good flowers.

• Why it matters: It pushes the plant to focus energy on the top canopy, improving quality and airflow.
• Related: Canopy

Definition: A support net or structure used to spread branches and hold up heavy flowers.

• Why it matters: Prevents branches from falling over and helps you keep an even canopy.
• Related: Stretch, Canopy

Definition: The process of water moving through the plant and evaporating from leaves.

• Why it matters: Transpiration helps move nutrients from roots to leaves. If transpiration is blocked (too humid or cold), plants can stall.
• Related: VPD, RH

Definition: A fungal disease that looks like white powder on leaves.

• Why it matters: It spreads fast in stagnant, humid conditions and can ruin quality if ignored.
• Easy version: PM is a warning sign that airflow and humidity control need work.
• Related: Airflow, RH

Definition: A structured approach to preventing and managing pests and diseases using observation, sanitation, and targeted actions.

• Why it matters: The goal is prevention first, then small corrections, not panic spraying.
• Easy version: IPM is a system, not a product.
• Related: Pest ID Tool

Definition: Drying removes moisture from harvested flower, and curing stabilizes it over time for better aroma and smoothness.

• Why it matters: You can grow great flower and still ruin it with a fast, hot dry. Controlled drying preserves terpenes.
• Related: Terpenes