Cannabis Training Guide: Double Your Yields

Why Train Cannabis Plants?

In nature, cannabis grows with a central main stem (apical dominance) that receives the majority of growth hormones. This produces one large central cola and smaller side branches—like a Christmas tree shape.

The problem for indoor growers: Grow lights have limited penetration. Only the top of the plant receives optimal light while lower buds get shaded, producing airy "larf" instead of dense nugs.

Training solves this by:

• Breaking apical dominance: Redistributing growth hormones to create multiple main colas.
• Creating an even canopy: All bud sites receive equal light, producing uniform dense buds.
• Maximizing grow space: A flat, wide plant uses square footage more efficiently than a tall, narrow one.
• Improving airflow: Open canopy structure reduces mold and pest risks.

LST vs HST: Understanding the Difference

Training techniques fall into two categories based on how much stress they inflict on the plant:

Low Stress Training (LST)

LST involves gently bending and tying down branches without damaging plant tissue. Since there's no wound to heal, plants continue growing immediately.

• Techniques: Bending, tying down, SCROG
• Recovery time: None
• Autoflower safe: Yes ✅
• Best for: All plants, beginners, autoflowers, limited veg time

High Stress Training (HST)

HST involves cutting, pinching, or breaking the plant, which triggers a stress response and requires recovery time before growth resumes.

• Techniques: Topping, FIM, supercropping, mainlining
• Recovery time: 3-10 days
• Autoflower safe: No ⚠️ (stunts growth)
• Best for: Photoperiod strains with extended veg time

Topping: The Classic Technique

Topping is the most common HST technique. You cut off the main growth tip (apical meristem), forcing the plant to redirect growth hormones to the two branches below, creating two main colas instead of one.

How to Top Cannabis

1. Wait for 4-6 nodes: Don't top too early—the plant needs enough leaves for photosynthesis.
2. Sterilize scissors: Clean cuts prevent infection.
3. Cut above a node: Snip the main stem just above the 4th or 5th node, leaving a small stub.
4. Wait 3-7 days: Two new shoots will emerge and become main colas.
5. Repeat if desired: Each top can be topped again after 1-2 weeks, doubling colas (2→4→8→16).

FIM: "F*** I Missed"

FIM (the name comes from a grower's accidental discovery) is similar to topping but involves removing only 75% of the growth tip instead of 100%. This often produces 4+ new growth shoots instead of 2.

FIM vs Topping

• FIM: Remove ~75% of growth tip. Results in 4+ tops (variable).
• Topping: Remove 100% of growth tip. Results in exactly 2 tops (predictable).

FIM is slightly less stressful than topping and recovers faster, but results are less predictable. Some growers prefer FIM for creating bushier plants quickly.

LST: Low Stress Training

LST is the gentlest training method and works for all cannabis plants, including autoflowers. By bending branches horizontally, you expose lower growth to light and trick the plant into treating multiple branches as "main" colas.

How to LST Cannabis

1. Start early: Begin when stems are still flexible (week 3-4 of veg).
2. Bend the main stem: Gently bend the main stem 90° and tie it to the pot edge with soft plant ties.
3. Spread branches outward: As new branches grow upward, bend and tie them down too.
4. Maintain daily: Continue spreading growth outward throughout veg.
5. Goal: A flat, star-shaped canopy where all branches are at equal height.

SCROG: Screen of Green

SCROG (Screen of Green) combines LST with a physical screen (usually a net or wire grid) placed 8-12 inches above the plant. As branches grow through the screen, you tuck them back under and spread them outward, filling every square of the grid.

SCROG Benefits

• Maximum canopy coverage: Every inch of your grow space produces buds.
• Even light distribution: Flat canopy means all buds get equal PPFD.
• Fewer plants needed: One well-SCROG'd plant can fill a 4x4 tent.
• Easier canopy management: The screen provides structure during flower.

When to Flip in SCROG

Switch to 12/12 flowering when the screen is 60-70% filled. The flowering stretch will fill the remaining 30-40%. Continue tucking during the first 2-3 weeks of flower until stretch ends.