Cannabis Plant Care &
Garden Maintenance Guide

For full nutrient schedule details by medium and growth stage, see Module 09 — Nutrients Guide. For a complete grow media comparison including pre-buffering coco, see Module 08 — Growing Media Guide.

Identifying Nutrient Deficiencies by Leaf Location

The final 2–3 weeks RH reduction to 40–45% is specifically Botrytis (bud rot) prevention — at this stage a dehumidifier stops being optional and becomes essential, especially in humid climates or dense canopies.

For VPD targets by stage, night temperature management, and DIF (day-to-night differential) guidance, see Module 07 — Environment & Climate Guide.

Training Techniques at a Glance

Both techniques can be combined with LST for a wide, productive canopy. Multiple toppings or FIMs (topping each new main cola as it develops) is called manifolding or mainlining — an advanced technique that creates perfectly symmetrical plants with 4, 8, or 16 even colas.

Why ScrOG Increases Yield

In an untrellised plant, the top cola gets the most light and the lower branches receive increasingly less. ScrOG eliminates this light gradient by forcing all growth to the same horizontal plane — every bud site sits at the same distance from the light. This converts a plant that would produce one large top cola and many smaller secondary buds into a plant where every bud site has the same yield potential.

ScrOG Setup — Step by Step

• 1Install the screen at 12–18 inches above the pot rim. Trellis netting (typically 4×4 inch squares) works best — available as rolls that can be cut to any tent size and suspended from tent poles or a PVC frame. For a 4×4 tent, 4×4 feet of netting is standard.
• 2Veg the plant until branches reach the screen — this usually takes 4–6 weeks in an indoor environment. Top or FIM once before the screen is introduced to encourage lateral branching before horizontal training begins.
• 3Tuck branches under the screen as they grow up through it. Guide each branch to an open square rather than letting it grow straight up through one hole. The goal is 1–2 branches per screen square when the screen is full.
• 4Flip to 12/12 when 70–80% of the screen is filled. Filling the screen more before flipping is tempting but not beneficial — overfilled screens reduce airflow through the canopy and create humidity problems during flower.
• 5Stop tucking at day 14–21 of flower. After this point, let all branches grow straight up through the screen. A second screen can be installed at 8–10 inches above the first to support heavy cola weight in late flower.

Primary Hermaphroditism Triggers

• Light leaks during the dark period: Any light exposure during the 12-hour darkness cycle can interrupt the flowering hormone (phytochrome) signal. Even a phone screen, indicator LED, or a gap in tent zipper is sufficient. Inspect your tent in complete darkness to find and seal all light entry points before flipping
• Heat stress above 85°F sustained: Prolonged heat stress during flower triggers survival mechanisms including hermaphroditism — the plant attempts to self-pollinate before it dies. Keep the flowering canopy below 82°F
• Severe nutrient deficiency or toxicity in flower: Extreme calcium deficiency, iron lockout, or nitrogen toxicity in flower can stress the plant into hermaphroditism. This is why monitoring EC and pH throughout flower is not optional
• Elevated stress sensitivity in feminized seeds: Feminized seeds are bred under controlled stress conditions and retain slightly higher stress sensitivity than regular seeds. This doesn't mean they commonly hermaphrodite — it means stable environmental management is especially important with fem genetics

If You Find Male Pollen Sacs

Remove the affected branch or bud site immediately with clean scissors. If pollen sacs are found on multiple branches, consider whether to harvest early rather than risk seeding the entire crop. Pollen sacs that have not yet opened can be carefully removed; any that have already opened have already released pollen into the environment.

Spider Mite Identification Progression

• 1First sign (often missed): Tiny pale stippled dots on the upper leaf surface — each dot is where a mite pierced a cell and drained the contents. Individual dots are smaller than a period. Under a loupe, the leaf surface looks like it has been lightly sandblasted.
• 2Early infestation: Turn leaves over and examine undersides with a 30x loupe. You'll see tiny moving dots (the mites themselves, often reddish-tan), along with eggs appearing as clear spherical balls attached to the leaf surface.
• 3Established infestation: Fine silky webbing begins appearing between leaf axils and on the undersides of leaves. At this stage you're dealing with thousands of mites. Treatment becomes significantly more difficult.
• 4Advanced infestation: Visible webbing across multiple plants, widespread stippling causing leaves to bronze and drop, and mites visible to the naked eye as tiny moving specks. Immediate aggressive treatment is required.

Biological Controls — Predatory Insects

Biological Fungicides

• Bacillus subtilis (e.g., Serenade): Preventive and early-curative against powdery mildew and damping-off; colonizes plant surfaces and outcompetes pathogenic fungi — most effective when applied before or at first signs of infection
• Trichoderma harzianum: Root zone biological that suppresses Fusarium and Pythium root rot; applied as a root drench; most effective when introduced at transplant
• Beauveria bassiana: Entomopathogenic fungus that infects and kills thrips, aphids, and whiteflies; spores attach to insect exoskeletons and germinate — safe for plants and humans, target-specific

Spray Treatments — With Correct Protocols

Trichome Color Guide

Pistil Color — Secondary Indicator Only

White straight pistils indicate immaturity. As buds ripen, pistils curl and darken to orange, red, or brown. A 70–90% darkened pistil count corresponds roughly to the harvest window in most strains. However, pistils are affected by humidity changes, physical contact, and pollination — all of which can darken them prematurely without the plant being ripe. Always confirm pistil observations with trichome inspection.

For full trichome inspection protocol, strain-specific harvest windows, and flushing guidance, see Module 13 — Harvest & Processing Guide.

Drying — The Conditions That Matter

Terpenes are volatile aromatic compounds that begin evaporating rapidly above 65°F. Below 55% RH, the outer surface of the bud dries faster than the interior moisture can equalize through the dense flower tissue — the result is a dry exterior with wet interior that produces the "hay smell" (chlorophyll degradation) that no amount of curing will fully fix. The correct approach is a slow, controlled dry at the low end of the temperature range.

Drying Readiness Test

Take a small branch and bend it. If it snaps cleanly — drying is complete. If it bends without breaking or if the outer material flexes away from a slightly moist core, give it another 2–3 days. This test applies to the smallest secondary branches, not the main stem. Over-dried flower is not fixable; under-dried flower can still cure.

Curing Protocol

• 1Trim buds from stems and place loosely in wide-mouth airtight glass jars — do not pack tightly. Fill jars to approximately 75% full to allow airspace.
• 2Store in a cool, dark location at 60–65°F. A basement or cabinet away from light is ideal. Avoid refrigerators (too dry) and warm areas near appliances.
• 3Burp jars daily for the first 2 weeks: Open each jar for 15–20 minutes to release moisture and refresh the air inside. If you smell ammonia when opening, the buds are too wet — leave them open for several hours before resealing and monitor closely for mold.
• 4After 2 weeks, reduce burping to 2–3 times per week. After 4 weeks, weekly burping is sufficient. At 4 weeks, the cure is the minimum standard; 6–8 weeks produces measurably smoother, more complex flavor as terpene expression matures and chlorophyll degrades completely.

For full harvest processing guidance including wet vs. dry trimming, storage, and long-term preservation, see Module 13 — Harvest & Processing Guide.

Timing for Northern Climates (Zone 3–5)

Key Outdoor Success Factors

• Minimum 6 hours of direct sunlight daily: Cannabis is a heavy light feeder outdoors — less than 6 hours produces significantly reduced yield and potency. South-facing slopes or unshaded raised beds are ideal
• Well-draining soil or raised beds: Avoid clay soils or areas with standing water after rain — compacted wet soil is the primary cause of outdoor root problems. Large fabric pots (15–25 gallons) are an excellent alternative to in-ground planting for drainage control
• Pest and wildlife management: Outdoor plants are exposed to insects, deer, rodents, and birds. Install physical fencing for deer; use organic pest controls (neem in veg, potassium bicarbonate for mildew) throughout the season; inspect for aphids and spider mites weekly
• Bud rot prevention in late season: Dense outdoor buds in humid late-summer conditions are highly susceptible to botrytis. Remove large fan leaves and lower growth in late flower to improve airflow through the canopy; monitor dense colas after any rain event
• Legal compliance: Check current state and local regulations regarding outdoor cultivation before beginning. Many jurisdictions restrict plant count, require screening or fencing, or prohibit visible cultivation