Grower reference
Grow stage target bands
Target ranges for air temperature, humidity, feed EC and pH, and light — stage by stage, from seedling through to dry and cure. Ranges are a starting point to log against, not a rule: cultivars move at different speeds and tolerate different conditions.
Seedling / propagation
Warm and humid, with light kept low while the root system is still developing.
| Metric | Target range |
|---|---|
| Air temperature | 24–26 °C (75.2–78.8 °F) |
| Relative humidity | 70–80 % |
| Input feed ECSoilless or hydro, nutrient solution as mixed — not runoff | 0.6–0.8 mS/cm |
| Input feed pHSoilless or hydro, as mixed — not runoff. In soil, aim for roughly 6.0–6.8 | 5.8–6.2 |
| PPFD | 100–250 µmol/m²/s |
Vegetative
A pronounced day/night temperature split opens up. Humidity comes down and feed strength climbs as the plant builds structure.
| Metric | Target range |
|---|---|
| Air temperature (lights on) | 24–27 °C (75.2–80.6 °F) |
| Air temperature (lights off) | 19–22 °C (66.2–71.6 °F) |
| Relative humidity | 60–70 % |
| Input feed ECSoilless or hydro, nutrient solution as mixed — not runoff | 1–1.8 mS/cm |
| Input feed pHSoilless or hydro, as mixed — not runoff. In soil, aim for roughly 6.0–6.8 | 5.8–5.9 |
| PPFD | 400–700 µmol/m²/s |
| DLIDepends on your photoperiod — DLI ≈ PPFD × light-hours × 0.0036. Reconcile with the PPFD row for your own schedule rather than hitting both independently | 25–40 mol/m²/day |
Transition / pre-flower
The stretch. Humidity drops toward flower levels and feed strength ramps up, though it has not yet reached its flower peak.
| Metric | Target range |
|---|---|
| Air temperature (lights on) | 20–26 °C (68–78.8 °F) |
| Air temperature (lights off) | 18–21 °C (64.4–69.8 °F) |
| Relative humidity | 50–60 % |
| Input feed ECSoilless or hydro, nutrient solution as mixed — not runoff | 1.6–2 mS/cm |
| Input feed pHSoilless or hydro, as mixed — not runoff. In soil, aim for roughly 6.0–6.8 | 5.8–6 |
| PPFD | 600–800 µmol/m²/s |
| DLIDepends on your photoperiod — DLI ≈ PPFD × light-hours × 0.0036. Reconcile with the PPFD row for your own schedule rather than hitting both independently | 30–40 mol/m²/day |
Flower
Peak light and feed, with humidity held down to protect dense buds from rot.
| Metric | Target range |
|---|---|
| Air temperature (lights on) | 20–26 °C (68–78.8 °F) |
| Air temperature (lights off) | 17–20 °C (62.6–68 °F) |
| Relative humidity | 40–50 % |
| Input feed ECSoilless or hydro, nutrient solution as mixed — not runoff | 1.8–2.6 mS/cm |
| Input feed pHSoilless or hydro, as mixed — not runoff. In soil, aim for roughly 6.0–6.8 | 5.8–6 |
| PPFD | 700–1000 µmol/m²/s |
| DLIDepends on your photoperiod — DLI ≈ PPFD × light-hours × 0.0036. Reconcile with the PPFD row for your own schedule rather than hitting both independently | 35–45 mol/m²/day |
Late flower / flush
Cooler and drier still. Any taper or flush should follow evidence — runoff EC, leaf-tip burn, visible salt stress — rather than the calendar; a plant still building tissue should not be starved.
| Metric | Target range |
|---|---|
| Air temperature (lights on) | 18–24 °C (64.4–75.2 °F) |
| Air temperature (lights off) | 17–20 °C (62.6–68 °F) |
| Relative humidity | 40–45 % |
| Input feed EC (during a flush)Applies once a flush is underway, not on reaching late flower. Hold the flower range until runoff or leaf evidence says otherwise. Soilless or hydro, as mixed — not runoff | 1–1.6 mS/cm |
| Input feed pHSoilless or hydro, as mixed — not runoff. In soil, aim for roughly 6.0–6.8 | 5.8–6 |
| PPFD | 700–900 µmol/m²/s |
| DLIDepends on your photoperiod — DLI ≈ PPFD × light-hours × 0.0036. Reconcile with the PPFD row for your own schedule rather than hitting both independently | 30–40 mol/m²/day |
Dry & cure
These bands describe the drying room: dark, cool, held to a narrow band, with gentle airflow — stagnant air lets damp pockets form even when the room average reads right. Curing is a different measurement: once the material is in jars or bags the humidity that matters is the one inside the container, which a safe room reading tells you nothing about. Light, feed and pH targets no longer apply once the plant is cut.
| Metric | Target range |
|---|---|
| Air temperature | 15–16 °C (59–60.8 °F) |
| Relative humidity (drying room)Ambient reading while drying. Once the material is jarred, the equivalent figure is measured inside the container, not in the room | 58–62 % |
Log your grow against these targets
Verdant is a grow diary that keeps your readings, photos and notes in one place, so you can look back at what a run actually did instead of reconstructing it from memory.
Common questions
- What are grow stage target bands?
- A target band is the range a given environmental or feed metric typically sits in for a specific grow stage — for example 40–50 % relative humidity during flower. They are ranges rather than single numbers because plants tolerate variation, and they are contextual baselines to compare your own readings against rather than a pass/fail test. Cultivar, canopy position, and how the plant is actually responding all shift what is right for a given room, so a healthy plant sitting outside a band is a reason to look, not automatically a reason to change something.
- Why do temperature targets differ between lights on and lights off?
- Mainly because the room cools once the lamps are off, so lights-on and lights-off are genuinely different environments and each needs its own target rather than one averaged figure. The split is not a VPD control on its own: VPD depends on temperature and humidity together — and ideally on leaf temperature — so at a fixed humidity a cooler night lowers VPD rather than holding it steady. Work VPD out separately for each part of the cycle.
- Why are there no light or feed targets for dry and cure?
- Once the plant is cut it no longer takes up nutrients or photosynthesises, so EC, pH, PPFD and DLI stop applying. Temperature and humidity are the only numeric targets left, and both are held tight to control the drying rate — but they are not the whole picture. A drying space should also be dark and gently ventilated: stagnant air lets damp pockets form around dense material even when the room average reads correctly.
- Do the EC and pH targets apply to soil?
- No — the feed EC and pH ranges above are soilless and hydro figures. Soil buffers pH, so soil growers should aim for roughly 6.0–6.8 rather than the high-5s shown here. Air temperature, humidity and light targets are not medium-specific and apply either way.
- Are the EC and pH targets for input feed or runoff?
- Input only — the solution as you mix it, before it reaches the medium. Runoff EC normally reads higher than input because salts accumulate in the root zone. Runoff pH is different: it can drift in either direction, so a downward drift is just as meaningful as an upward one. Read both against your own input and root-zone history rather than against these bands.
- Should I flush at the end of flower?
- Not automatically. Base any taper or flush on evidence — runoff EC, leaf-tip burn, or visible salt stress — rather than on the calendar. Aggressive late-stage flushing can weaken a plant that is still filling out.
- Do the dry and cure numbers mean the same thing?
- No, and the difference matters. The temperature and humidity bands shown describe the drying space — an ambient room reading, taken while the material is hanging or on racks. Curing happens in sealed jars or bags, where the humidity that counts is the one inside the container. A room sitting comfortably in range tells you nothing about a jar holding too much moisture, which is where mould tends to appear, so measure inside the container once the material is packed and burp it on what that reading says.
- Are these targets the same for every cultivar?
- No. These are a starting point drawn from a standard operating procedure, and cultivars differ — some tolerate more heat, some finish faster. Treat the bands as a default to log against and adjust from, not a rule.