Biobizz & Indoor Growing – A Guide from Seed to Harvest

Indoor Growing – Complete Guide from Seed to Harvest

Indoor growing of cannabis offers complete control over the environment – light, temperature, humidity, nutrients, and air circulation. Unlike outdoor growing, you're not dependent on weather, and annual harvests turn into year-round production. This guide will walk you through the entire process from equipment selection through germination, vegetative and flowering stages, to harvest, drying, and curing – with emphasis on practical details that beginners most often overlook.

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Equipment Selection

Grow tent (growbox)

A grow tent forms the foundation of every indoor setup. A reflective inner surface made of Mylar maximizes light utilization and the enclosed space makes microclimate control easier.

Recommended sizes:

What to focus on when selecting:
- Light-tight zippers – even small light leaks can disrupt the dark period in photoperiodic varieties.
- Robust metal frame with sufficient load capacity for LED panel, fan, and filter.
- Adequate number of ducting ports for ventilation and cables.
- Mylar inner surface – reflectivity over 90%, significantly better than white paint.

Lighting

Light is the most important factor in all indoor growing – it directly affects growth speed, bud size, and cannabinoid content. Modern full-spectrum LED technology currently dominates the market and represents the optimal choice for most growers.

Types of lighting:

Modern full-spectrum LED panels compared to HPS offer triple the efficiency (up to 3.0 µmol/J), full spectrum coverage including UV and far-red diodes, significantly lower heat production, and lifespan exceeding 50,000 hours. Premium models allow dimming and programmable spectrum, which you'll appreciate when fine-tuning conditions during different growing stages.

Power calculation rule:
- LED: 30–50 W per square foot (320–540 W per m²).
- For a 120 × 120 cm tent, you need an LED panel of 460–780 W power.

Practical tip: invest in a higher quality LED panel right from the start – light cannot be compromised and subpar lighting reduces yields throughout the entire cycle.

Ventilation and Air

Proper ventilation serves three critical functions: provides CO₂ supply for photosynthesis, removes heat and humidity (preventing mold development), and gentle air movement mechanically stimulates stems to grow stronger.

Basic ventilation setup:

1. Exhaust fan with carbon filter – removes hot, humid air and eliminates odor. Power in m³/h should match tent volume × 60 (air exchange 1× per minute), with additional allowance for filter resistance.
2. Intake opening – passive fresh air intake through an opening at the bottom of the tent.
3. Circulation fan – one or more small fans inside the tent prevent air stagnation and evenly distribute temperature and CO₂.

Calculation example: Tent 120 × 120 × 200 cm = 0.288 m³. For air exchange 1×/min you need an exhaust fan with nominal power of at least 17 m³/hour. With a carbon filter (which adds resistance) choose a fan rated for 150–250 m³/hour, ideally with speed control.

Growing Medium

For beginners, soil is undoubtedly the best choice – naturally buffers pH and well-amended substrates (BioBizz All-Mix, Plagron Royal Mix) supply the plant with nutrients for 3–4 weeks without requiring dosing. Coco coir offers faster growth but requires more precise care – not suitable as a first medium.

Pots

Air pots and fabric (textile) pots have a decisive advantage over standard plastic: air pruning of roots prevents spiraling root binding and promotes a branched, dense root system. The result is better nutrient uptake and a more robust plant.

Measuring Instruments

Without proper measurement, you're growing blind – investment in basic instruments will repay itself many times over in harvest quality:

• pH meter – controlling irrigation water pH is absolutely critical. Mechanical drop testers are insufficient.
• EC/TDS meter – measuring nutrient concentration in irrigation water and runoff.
• Thermometer + hygrometer – ideally with data logger for tracking overnight fluctuations.
• Magnifying glass or microscope (60–100×) – without this tool you cannot reliably determine the optimal harvest time.

Seed Germination

Germination Methods

Wet paper towel method (most common):

1. Place seeds between two damp paper towels.
2. Insert into a sealed bag or between two plates.
3. Maintain temperature of 22–26 °C – ideally on a heat mat or specialized germination pad.
4. Check moisture daily; the towel must not dry out or be too wet.
5. Once the root reaches 1–2 cm (usually 24–72 hours), transplant into medium – root side down.

Direct sowing into medium:

1. Evenly moisten the soil.
2. Make a hole 1–1.5 cm deep.
3. Place seed point-down.
4. Lightly cover with soil without compacting.
5. At proper temperature and moisture, the sprout appears in 3–7 days.

In a glass of water:

1. Place seeds in a glass of room-temperature water.
2. After 12–24 hours, seeds should sink to the bottom – if not, gently push them down.
3. Once the root extends to 1–2 cm, transplant into medium.

Seedling Stage (Week 1–2)

Seedlings are most vulnerable in the first two weeks – overwatering is the most common cause of death during this period.

• Light: CFL, T5, or LED at 30–50% power, 18–24 hours daily, 30–50 cm distance from top.
• Temperature: 22–26 °C.
• Humidity: 65–80% – transparent plastic cup or plastic wrap over seedling creates a mini greenhouse.
• Watering: Very gentle – water only the immediate area around the stem, not the entire soil surface.
• Nutrients: In pre-amended soil, none. In coco coir, start at 1/4 of recommended dose.

For selecting proper seeds for indoor growing, we recommend our indoor seed selection or read our seed type comparison.

Vegetative Phase

Light Cycle

The vegetative phase requires a long day – most commonly used setting:

• 18/6 (18 hours light, 6 hours dark) – best compromise between growth speed and electricity consumption. Suitable for both photoperiodic and autoflowering varieties.
• 20/4 – slightly faster growth at higher electricity cost. Especially suitable for autoflowers.
• 24/0 – continuous light, controversial approach. Current research suggests a 6-hour dark period has non-negligible benefits for plant physiology.

With photoperiodic varieties, you completely control the length of the vegetative phase – 3 weeks for smaller plants, 8+ weeks for maximum yield. With autoflowers, the transition to flowering is genetically fixed and occurs automatically after 2–4 weeks regardless of light cycle.

Optimal Conditions

Nutrients in Vegetative Phase

In the vegetative phase, the plant prioritizes building leaf area and stems, so nitrogen is the dominant nutrient. Typical NPK ratio: 3-1-2 or 4-2-3.

Macronutrients:
- Nitrogen (N) – key to chlorophyll formation and vegetative growth.
- Phosphorus (P) – root system development, foundation for later flowering.
- Potassium (K) – overall plant health, stress and disease resistance.

Secondary nutrients:
- Calcium (Ca) – cell wall strength.
- Magnesium (Mg) – central atom of chlorophyll, essential for photosynthesis.
- Sulfur (S) – amino acid and enzyme formation.

Micronutrients: Iron, manganese, zinc, boron, copper, molybdenum – needed in small amounts but deficiencies manifest quickly.

Cal-Mag: When growing under LED or in coco coir, calcium and magnesium supplementation is almost essential. LED panels, unlike HPS, don't produce infrared radiation, which affects transpiration and thus Ca and Mg uptake.

Training Techniques

Training creates an even canopy with multiple tops – key to maximizing light utilization and higher yields.

Low-Stress Training (LST):
- Progressive bending and tying of branches to the pot edge.
- Suitable for all types including autoflowers.
- No injury occurs, no recovery time needed.
- With proper execution, increases yield by 20–40%.

Topping:
- Removing the main top at the 3rd–5th node creates two new dominant tops.
- Exclusively for photoperiodic varieties – with autoflowers, causes yield loss with no compensation opportunity.
- Increases yield by 30–50%, but requires 3–5 days for recovery.

FIMming:
- Remove only 70–80% of the top shoot – less precise than topping but less stressful.
- Can result in 3–4 new tops instead of two.

ScrOG (Screen of Green):
- Horizontal net (5 × 5 cm mesh) above plants through which branches are woven.
- Creates an even light canopy with maximum area coverage.
- Most efficient technique for yield per m² – requires more setup but results are exceptional.

Defoliation:
- Targeted removal of large fan leaves that shade lower levels.
- Perform modestly and at the right time: end of vegetative phase and week 3 of flowering.
- Excessive defoliation weakens the plant – leaves are the primary energy source.

Transition to Flowering (Photoperiodic Varieties)

When to Switch to 12/12

Current plant height is the key guide, since after switching to 12/12, the plant will grow another 50–100% (the "stretch"). Switch when the plant reaches approximately 50% of its target final height.

For a 180 cm tent with LED panel and filter: switch at plant height of 40–60 cm. Stretch lasts the first 2–3 weeks after switching – continue LST during this time to keep the canopy even.

What Happens When Switching

1. Days 1–3: Plant registers the change in night length.
2. Days 3–7: Production of flowering phytohormones begins (gibberellins, auxins).
3. Week 1–3: Intense stretch – plant can grow 50–100% in height.
4. Week 2–3: First pistils (white hairs) signal the start of calyx formation.
5. Week 3+: Stretch slows, energy stores shift to bud building.

Flowering Phase

Light Cycle

Photoperiodic varieties require 12/12. Critical rule: the dark period must be absolutely uninterrupted. Even brief lighting during night (light leak from zipper, fan indicator LED) can:
- Cause revegging – return to vegetative phase.
- Induce hermaphroditism – female plant begins producing male pollen sacs.
- Significantly slow or stop bud formation.

With autoflowers, the light cycle remains 18/6 or 20/4 throughout growth. Switching to 12/12 for autoflowers is unnecessary and reduces yield.

Optimal Conditions

Reducing humidity in late flowering is critical – dense buds trap moisture inside and create ideal conditions for botrytis (gray mold). Lower night temperatures near the end of the cycle (16–18 °C) can additionally promote anthocyanin formation and increase trichome density.

Nutrients in Flowering Phase

Nutritional needs change dramatically during flowering. Nitrogen takes a backseat – its excess leads to loose, leafy buds with lower cannabinoid content. Phosphorus and potassium come to the fore.

Typical NPK ratio in flowering: 1-3-2 or 0-3-3.

Bloom boosters with high PK (e.g., PK 13/14) add during weeks 3–6 of flowering to increase bud density and weight. Don't exceed recommended doses – overfeeding in flowering is as harmful as in vegetative phase.

Flowering Phase Week by Week

Weeks 1–2: Stretch
- Intense vertical growth, continue LST.
- Gradually transition from vegetative to flowering nutrients.

Weeks 3–4: Bud Formation
- Calyxes with pistils multiply rapidly, buds become visible.
- Stretch slows, apply full doses of flowering nutrients.
- Defoliation to expose lower areas to light.

Weeks 5–6: Filling
- Buds gain volume and density, trichomes visible to the naked eye.
- Peak nutrient uptake throughout the entire cycle.
- Apply PK booster per manufacturer's instructions.

Weeks 7–8: Maturation
- Buds thicken and harden, trichomes transition from clear to milky.
- Pistils turn brown – percentage of white pistils drops below 30%.
- Lower EC of irrigation water to 1.0–1.4.

Weeks 8–9+ (indica) / 9–12+ (sativa): Flush and Harvest
- Final 1–2 weeks irrigate with pure water only.
- Monitor trichomes with magnifying glass: 70–80% milky, 10–20% amber = optimal window.
- Leaf yellowing is natural – plant shifts reserves into buds.

pH and EC – Key to Success

Why pH is Critical

Irrigation water pH determines which nutrients are accessible to the plant. Outside the proper range, lockout occurs – nutrients are present in the medium, but the plant cannot physiologically absorb them. The result is deficiency symptoms despite correct nutrient dosing.

Optimal pH range:

Tip: Minor pH fluctuation within the recommended range is beneficial – different nutrients have different pH optima for uptake. Intentionally alternate irrigation between values of 6.0 and 6.8 (soil) or 5.5 and 6.2 (coco/hydro).

EC (Electrical Conductivity)

EC expresses the total concentration of dissolved minerals in irrigation water. Too low causes underfeeding, too high causes root burn and water uptake blockage.

Recommended EC values:

How to Measure and Adjust pH

1. Mix the nutrient solution and let it stabilize for 1–2 minutes.
2. Measure pH with a calibrated meter.
3. Adjust with pH UP (potassium hydroxide) or pH DOWN (phosphoric acid) drop by drop – always wait and remeasure after adding.
4. Target: 6.0–6.8 for soil, 5.5–6.2 for coco/hydro.
5. Regularly measure runoff water pH – significant deviation from irrigation water signals salt buildup or pH drift in the medium, resolved by flushing.

Harvest – When and How

When to Harvest – Trichome Method

Observing trichomes under a magnifying glass or pocket microscope (60–100× magnification) is the only reliable method to determine optimal harvest time. Trichomes are stalked resinous glands on bud surfaces – THC, CBD, and terpenes concentrate in them.

Optimal harvest window:
- Energizing effect: 80% milky, 20% clear.
- Balanced effect: 70–80% milky, 10–20% amber (most common choice).
- Sedative effect: 50% milky, 50% amber.

Other Ripeness Indicators

• Pistils: 70–90% brown or orange. Predominance of white pistils signals the bud is still developing.
• Buds: Have stopped gaining volume and density.
• Sugar leaves: Begin curling back away from the bud.
• Fan leaves: Natural yellowing – plant shifts reserves into buds.

Harvest Procedure

1. Flush: 1–2 weeks before harvest, irrigate with pure water only. The goal is to minimize nutrient residues in tissue for cleaner taste and smoother burning.
2. 48 hours darkness: Some growers keep the plant in total darkness for 24–48 hours before harvest – assumed to increase resin production. The effect is individual and scientifically unproven, but the risk is minimal.
3. Cut: Cut the main stem just above the base.
4. Trimming: Remove large fan leaves. Wet trimming (immediately after cutting) is faster and easier; dry trimming (after drying) is gentler on trichomes but more labor-intensive.

Drying

Why Drying is Critical

Proper drying is as important as the grow itself. Too-quick drying produces harsh, sharp-tasting cannabis, burns unevenly, and may contain chlorophyll residue. Too-slow drying at high humidity creates ideal conditions for botrytis (gray mold) – the greatest enemy of the harvest.