Horticulture reference

Cannabis nutrient programs

Cannabis feed programs are described in horticulture references as the variable beginners most often overthink and most often miscalibrate by overdosing. Published material documents the plant as requiring different ratios of nitrogen, phosphorus, and potassium at each stage, calcium and magnesium across the whole life cycle, and a narrow pH window outside of which nutrients are documented as chemically unavailable regardless of concentration. This reference walks through the documented targets in the order published protocols describe them — seedling, veg, transition, flower — and then covers documented mixing order, the organic-versus-synthetic argument, and how the most-cited deficiencies appear in grower reports.

Documented NPK ratios by stage

Bottled nutrients list their ratios as three numbers — nitrogen, phosphorus, potassium — and the documented ratio shifts as the plant moves from leaf-building into bud-building. Seedlings are documented as requiring almost nothing for the first two weeks; the cotyledons are described in published material as carrying enough stored food to support the first true leaves, and a nutrient-loaded substrate at that stage is documented as burning root tips faster than feeding them. From week three through the end of veg, the documented target is a high-nitrogen ratio in the 3-1-2 or 4-2-3 neighbourhood — plenty of nitrogen for leaf and stem mass, moderate phosphorus for root expansion, and enough potassium to maintain cell wall integrity.^[1] Most veg-labelled bottles are documented as landing in this window.

The transition week — documented as the seven days either side of the photoperiod flip — is described in published protocols as wanting something closer to balanced, around 2-2-3 or 1-2-2, because the plant is documented as still completing its stretch while beginning to set flower sites. From week three of flower onward, the documented protocol describes switching to a bloom ratio in the 1-3-4 or 1-4-5 range; nitrogen demand is documented as dropping sharply once the canopy is built and bud sites are pulling phosphorus for resin and potassium for sugar transport. Overshooting nitrogen in mid-flower is documented as the classic miscalibration — producing oversized, leafy buds described in grower reports as smelling green and never quite finishing.

Calmag and the secondary nutrients in published protocols

Calcium and magnesium are documented in published references as the two micronutrients home growers most often run short on, with deficiencies described as appearing faster than NPK shortfalls. Cannabis is documented as pulling roughly 150 to 200 ppm of calcium and 50 to 75 ppm of magnesium across the life cycle, with most reverse-osmosis water and most coco-based substrates documented as starting with effectively zero of either.^[4] Documented calmag supplement protocols describe roughly 2.5 ml/L (2 to 4 ml per gallon, or 0.5 to 1 ml per litre) added to every feed in coco and hydro, and every second feed in soil — though seedling-stage dosing is documented as lighter, around 2.5 ml/L on the second feed. Tap water running 150 ppm or higher is documented as providing useful background calcium, with published protocols describing soil growers on hard tap water as often able to skip the supplement.

Silica is documented in published references as the one optional input consistently described as worth running. The documented dose is 1 ml per gallon of a potassium-silicate supplement through veg and the first three weeks of flower, with published reports describing strengthened stems, improved heat tolerance, and measurable pest and pathogen resistance.

EC targets and pH ranges as documented

EC, or electrical conductivity, is documented in published references as the single most useful number for tracking nutrient concentration in the feed water.^[2] The documented input EC ranges are 0.6 to 1.0 for seedlings, 1.4 to 1.8 for mid to late veg, 1.8 to 2.2 for early flower, and 2.0 to 2.4 through fat-bud weeks in coco; soil is documented as sitting about 0.2 lower across the board because the substrate itself buffers. Runoff EC is documented as ideally landing within 0.2 of input — runoff significantly higher than input is documented as indicating salt accumulation, with the published response being a flush with plain pH-corrected water. Runoff significantly lower than input is documented as indicating the plant is metabolizing faster than the feed supplies, with the published response being a dose increase.

pH is documented as the silent killer in published horticulture references. Cannabis is documented as wanting 6.2 to 6.8 in soil, 5.8 to 6.2 in coco, and 5.6 to 6.0 in hydroponics; outside those ranges, individual nutrients are documented as becoming chemically unavailable even when present in the water.^[3] A locked-out plant is documented as looking deficient regardless of feed concentration, with published references describing the documented response as a pH correction rather than a heavier dose. Published protocols describe checking pH on every mix and on every runoff sample for the first two months of a grow.

Mixing order described in references

The documented mixing order matters because some salts are documented as precipitating out of solution when introduced in the wrong sequence, leaving white sludge at the bottom of the tank and a weaker mix than the label suggests. The documented order in published references is water first, then silica if applicable, then calmag, then the A part of the base nutrient, then the B part, then any supplements, and pH correction last. Published protocols describe stirring for at least thirty seconds between each addition. Silica is documented as not getting along with calcium when the two are introduced together — they are documented as forming an insoluble precipitate, with both elements lost. Adding silica to plain water before anything else is documented as preventing the reaction.

Organic versus synthetic in grower reports

Synthetic nutrients are documented in published references as salt-based bottles delivering precise, immediately available nutrition, with growers steering by EC and pH alone. Organic nutrients are documented as relying on soil biology to break down composts, meals, and amendments into plant-available forms over time, with properly built living soil documented as carrying a plant from seed to harvest with nothing but water. Published reports describe the trade-off as control versus simplicity. Synthetics are documented as allowing deficiency correction within days and a specific terpene profile dialled in; organics are documented as producing noticeably more complex terpene profiles in side-by-side jar comparisons while punishing overfeeding and pH neglect with much slower recovery.

Published guidance for a first grow consistently describes synthetic in coco as the most forgiving combination — fast feedback, easy to flush, low-stakes mistakes. Moving to organic living soil for the second or third grow is documented as appropriate once the basics are automatic, with the documented payoff being increased flavour complexity at the jar stage balanced against slower problem-solving cycles.

Reading documented deficiencies

Mobile nutrients are documented in published references as showing deficiencies on old leaves first, because the plant translocates them to new growth; immobile nutrients are documented as showing on new leaves because the plant cannot redistribute what is already locked into older tissue. Nitrogen deficiency is documented as the most common and the easiest to read — pale, uniformly yellowing lower leaves that progress up the plant if untreated, described in published protocols as a documented feature of week six or seven of flower as the plant naturally pulls nitrogen out of fan leaves. Calcium deficiency is documented as rusty brown spots on mid-canopy leaves with curled tips, almost always associated in published references with a pH or calmag issue rather than a true shortage. Magnesium deficiency is documented as yellowing between the veins of mid-canopy leaves while the veins themselves remain green, with a calmag bump described as correcting it within a week.

Phosphorus shortage is documented as darkening old leaves to purple-bronze and stalling bud development; potassium shortage is documented as burning leaf edges with a yellow-then-brown crisp creeping inward. Both are documented as appearing most often in late flower when the plant is pulling hard and the feed has not kept pace. Before treating any deficiency, published protocols describe checking pH and runoff EC first — documented experience in grower reports describes seven out of ten apparent deficiencies as actually lockouts, with the documented fix being a flush and pH reset rather than a heavier dose of the missing nutrient.

Lockbox Seeds publishes reference material about cannabis horticulture for educational purposes only. Cannabis cultivation is regulated differently in every jurisdiction, and readers are responsible for understanding the legal status of cannabis where they live.