Growing Glossary

Real terms explained in plain English — no jargon for jargon’s sake, just what you actually need to know to understand your own grow.

VPD (Vapour Pressure Deficit)

The gap between how much moisture the air can hold and how much it’s actually holding, driven by temperature and humidity together. The single biggest overlooked factor in a healthy grow room — GrowLegend calculates it automatically from your climate readings.

EC (Electrical Conductivity)

A measure of how concentrated your nutrient solution is. Too low starves the plant, too high risks nutrient burn. GrowLegend’s Feeding Calculator tailors EC targets to your plant’s actual stage.

pH

How acidic or alkaline your water/soil is. Outside the right range (usually 6.0-7.0 in soil), roots can’t absorb nutrients properly even if they’re present — this is the real cause behind most “nutrient deficiency” symptoms.

PPFD (Photosynthetic Photon Flux Density)

How much usable light is actually hitting your canopy, measured in µmol/m²/s. Different from just “watts” — PPFD tells you what the plant can actually use.

DLI (Daily Light Integral)

The total light a plant receives over a full day, combining PPFD and photoperiod hours. GrowLegend calculates this automatically once you log a PPFD reading.

Node

The point on a stem where a leaf or branch grows out. Node spacing (the gap between nodes) is a good early health indicator — tight spacing usually means good light/genetics, stretchy spacing often means low light.

Root-Bound

When roots fill a container and start circling the inside walls instead of growing outward, stalling growth. Common when a plant stays too long in a small pot (like a solo cup past 2 weeks).

Nutrient Lockout

When nutrients are present in the soil but the plant can’t absorb them, usually from wrong pH, overfeeding, or cold roots. Looks like a deficiency but a flush (not more feeding) is usually the fix.

Transplant Shock

Temporary stress a plant shows after being moved to a new container — drooping, slow growth, sometimes stem kinks from physical handling. Usually resolves within a few days on its own.

Vegetative Stage

The growth phase where a plant builds leaves, stems and root mass before flowering. Photoperiod plants stay here as long as you keep them on 18+ hours of light; autos move through it on their own timer.

Flowering Stage

The stage where a plant produces buds, triggered by a 12/12 light schedule (photoperiod) or automatically by age (autoflower).

Photoperiod

A plant that flowers based on light schedule — you control when it flowers by switching to 12 hours of light/12 of dark.

Autoflower

A plant that flowers automatically based on age, regardless of light schedule. No control over veg length — if she’s stunted early, there’s no “waiting it out.”

Topping

Cutting off the main growing tip to encourage two new main colas instead of one, creating a bushier plant.

LST (Low-Stress Training)

Gently bending and tying down branches (instead of cutting) to shape the canopy and expose more bud sites to light.

Defoliation

Deliberately removing select leaves (usually large fan leaves) to improve light penetration and airflow to lower bud sites.

Flush

Watering with plain, no-nutrient water for a period to clear built-up salts from the soil — used both to fix nutrient lockout mid-grow and before harvest for a cleaner taste.

Curing

The slow-drying process after harvest, storing buds in jars and “burping” them daily to release moisture — GrowLegend’s Cellar module tracks this stage.

Snap Test

Bending a stem during drying; if it snaps cleanly it’s ready to jar, if it just bends it needs more drying time.

Trichomes

The small crystal-like structures on buds that produce cannabinoids — their color (clear → cloudy → amber) is the real signal for harvest timing, not just days in flower.

Phenotype

The individual physical traits (height, smell, color, structure) an actual plant expresses — even from the same strain, different seeds can express differently. GrowLegend’s Breeder Mode tracks this across a project.

Clone

A cutting taken from a mother plant, genetically identical to her (unlike a seed, which is a genetic mix of two parents).

IPM (Integrated Pest Management)

A layered approach to pest control (multiple products/methods rather than relying on one), used to break pest life cycles rather than just knock down what’s visible today.

Herm (Hermaphrodite)

A plant that develops both male and female parts, usually from stress — a real risk since it can pollinate a whole room’s female plants if not caught early.

Fox-Tailing

When buds grow in a stacked, twisted pattern instead of a normal round shape, usually from heat stress or certain genetics during flower.

Track all of this automatically in GrowLegend →