Reference
Grow glossary
The jargon, in plain language.
- VPDVapor Pressure Deficit
- A single number combining temperature and humidity that describes how strongly the air pulls moisture out of a leaf. It guides transpiration; most growers target ~0.8–1.2 kPa in veg and ~1.2–1.6 kPa in flower. Grow & Tell derives it from your logged day temp and humidity.
- pH
- How acidic or alkaline your water/feed is, on a 0–14 scale. Roots only absorb nutrients within a window (≈6.2–6.8 in soil, ≈5.5–6.2 in coco/hydro). Wrong pH causes 'lockout' that mimics a deficiency.
- PPM / ECParts Per Million / Electrical Conductivity
- Two ways to measure how concentrated a nutrient solution is. A TDS meter reads it so you can feed by numbers and compare input vs. runoff to see whether the plant is eating or salts are stacking up.
- N-P-K
- The three numbers on a nutrient bottle: Nitrogen, Phosphorus, Potassium. Veg growth wants more N; flowering wants more P and K.
- Photoperiod
- A plant that flowers based on its light schedule. Keep it on long days (e.g. 18/6) to grow leaves; switch to 12/12 to trigger flowering.
- Autoflower
- A plant that flowers automatically with age regardless of light schedule, usually finishing fast. Many growers run autos on a long light schedule start to finish.
- Vegetative (veg)
- The leafy growth stage before flowering, when the plant builds size and structure. This is when you do most training.
- Flowering
- The stage where the plant develops buds, triggered in photoperiods by switching to a 12/12 light cycle. Humidity should come down through this stage.
- The stretch
- A burst of vertical growth in the first weeks of flower, when a plant can roughly double in height. Leave headroom in your tent for it.
- Coco coir
- A soilless growing medium made from coconut husk. Fast and high-yielding but inert, so you supply all nutrients every watering and watch pH closely.
- Living soil
- Soil pre-amended with organic inputs and microbes that feed the plant over time, so you mostly just add water. The most forgiving medium for beginners.
- HydroponicsDWC, RDWC, NFT…
- Growing with roots in nutrient-rich water rather than soil. Fastest growth, but the least forgiving of mistakes. DWC (deep water culture) is the common entry point.
- LSTLow-Stress Training
- Gently bending and tying branches to flatten the canopy so light reaches more bud sites. No cutting and reversible, which makes it a low-risk place to begin.
- Topping
- Cutting off a growing tip above a node so one main cola becomes two. A 'high-stress' technique done during veg on a healthy plant.
- ScrOGScreen of Green
- Training growth into a horizontal net to fill it with an even canopy of tops. A natural next step after LST.
- Trichomes
- The tiny resin glands that coat the buds. Their color (clear → cloudy → amber) under magnification is the most reliable signal of ripeness for harvest timing.
- Curing
- Storing dried buds in sealed jars at about 58 to 62% humidity for weeks, 'burping' them periodically. It smooths smoke and develops aroma, and accounts for much of the final quality.
- Runoff
- The water that drains out the bottom of the pot after watering. Measuring its pH and PPM versus what you put in reveals what's happening at the roots.
Come across a term we haven't covered? We're growers too, and we're happy to help. Email us at support@growandtell.net and we'll do our best to help.