Grow reference card
One page, everything you check most.
Environment by stage
| Stage | °C | °F | RH | VPD kPa |
|---|---|---|---|---|
| Germination | 22–26 | 72–79 | 70–80% | 0.4–0.8 |
| Seedling | 20–25 | 68–77 | 65–75% | 0.5–0.8 |
| Vegetative | 22–28 | 72–82 | 55–70% | 0.8–1.1 |
| Flowering | 20–26 | 68–79 | 40–55% | 1.0–1.4 |
| Late flower / flush | 18–24 | 64–75 | 40–50% | 1.2–1.5 |
| Drying | ~15–18 | 59–64 | ~60% | — |
| Curing | 15–21 | 59–70 | 58–65% | — |
VPD is calculated at leaf temperature. A well-watered leaf sits within ~2 °C of air; under stress and low airflow it can run several degrees hotter, which shifts real VPD — so treat these as air-side targets with that caveat.
pH by medium
| Medium | Target pH | Why |
|---|---|---|
| Soil | 6.3–6.8 | Soil buffers, so it holds a range |
| Coco | 5.8–6.2 | Inert — you are setting the solution |
| Hydro | 5.5–6.0 | No buffer at all; stability matters more than the exact number |
Drifting out of band locks nutrients out even when they are present. Micronutrient availability in particular falls sharply as pH rises. Check pH before adding anything.
Deficiency quick-reference
| Where it shows | Likely | Tell |
|---|---|---|
| Old / lower leaves | N, P, K, Mg | Mobile — the plant moves them to new growth |
| New / upper growth | Ca, Fe, B, S | Immobile — cannot be relocated once placed |
| Whole lower leaf yellows evenly | Nitrogen | Uniform fade |
| Yellow between veins, veins stay green | Magnesium | Interveinal pattern |
| Burnt / clawed tips | Over-feeding | Often mistaken for deficiency |
In flowering cannabis the textbook pattern bends: calcium deficiency has been documented starting in the LOWER fan leaves. Late-flower fade is also routinely misread as deficiency.
Dry & cure
| Phase | Target | Done when |
|---|---|---|
| Dry | ~60 °F / 60% RH, dark, gentle airflow | Small stems snap — about 12–14% moisture (water activity 0.65–0.70) |
| Cure | 62% RH in sealed jars | Burp daily week 1, then every few days |
| Store | Cold and dark — 4 °C beat 25 °C over a year of testing | Whole flower keeps better than ground |
Controlled, cool drying preserves terpenes better than simply drying slowly — the best-controlled trial to date dried faster and kept more.
Harvest
Judge trichomes with a 60x loupe, not the breeder's week count. Mostly cloudy is the common target; some amber for a heavier effect. Cannabinoid concentration rises to a peak then declines, so later is not automatically stronger — and amber does not mean THC has converted to CBN on the plant. That is post-harvest oxidation.
Track your own grow free — the journal grades your environment against these bands →
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