Plant Training Techniques Guide
Cannabis Plant Training Techniques
Master these training methods to increase yields, improve light penetration, and make better use of your growing space. Each technique can dramatically improve your harvest results when applied correctly.
Why Train Cannabis Plants?
Natural Cannabis Growth Pattern
Cannabis naturally grows in a Christmas tree shape with a dominant central cola. This apical dominance results in:
- Most energy focused on the main cola
- Lower branches receiving less light and producing smaller buds
- Inefficient use of light and growing space
- Uneven canopy with varied bud development
Benefits of Plant Training
Training techniques modify plant structure to:
- Create multiple main colas instead of just one
- Develop an even canopy for better light distribution
- Increase yields by 20-100% in the same space
- Improve air circulation to reduce pest and mold issues
- Keep plants shorter for limited height environments
Low Stress vs High Stress
Low Stress Training (LST)
- Gently bends and ties down branches
- Minimal recovery time needed
- Lower risk of hermaphroditism
- Can be performed throughout veg and early flower
- Ideal for autoflowering plants
High Stress Training (HST)
- Involves cutting/removing plant parts
- Requires recovery time (days to weeks)
- More dramatic growth changes
- Best performed in early-mid vegetative stage
- Not recommended for autoflowers
Choosing the Right Technique
Select training methods based on:
- Plant type: Photoperiod vs Autoflowering
- Grow space: Height limitations, grow style
- Experience level: Start with simple techniques
- Time available: Some methods require more maintenance
- Growth stage: Different techniques work at different times
Note: Always ensure plants are healthy and unstressed before applying training techniques. Plants need adequate nutrients, water, and light to recover properly from training.
Low Stress Training (LST)
Beginner-Friendly
What is LST?
Low Stress Training involves gently bending and tying down the main stem and branches to create a flat, even canopy. This technique breaks the plant's apical dominance without cutting, allowing multiple bud sites to receive direct light and develop into main colas.
Step-by-Step Guide
- Start early: Begin when the plant has 3-4 nodes (sets of leaves), typically 2-3 weeks from seed.
- Prepare your ties: Use soft plant ties, twist ties, pipe cleaners, or garden wire covered with a soft material.
- Bend the main stem: Gently bend the top of the plant horizontally, parallel to the soil. Secure it to the pot rim or use stakes in the soil.
- Create anchor points: Drill small holes around pot rims or place stakes in soil for securing ties.
- Train branches outward: As side branches grow upward, tie them down and outward to create a circular or star pattern.
- Adjust regularly: Check every 2-3 days and adjust ties as plants grow. Add new ties as needed.
- Continue throughout veg: Maintain LST through the vegetative stage and into the first week or two of flowering.
Pro Tips
- Always bend stems when they're most flexible (after watering)
- If a branch feels too rigid, don't force it – gradual training is safer
- Position ties a few inches from the growing tip
- Use fabric pots with built-in tie-down points for easier LST
- Combine with leaf tucking to expose bud sites without removing leaves
- Create a "manifold" effect by LST-ing branches into a symmetrical pattern
Ideal For
- Autoflowering plants (safer than high-stress methods)
- Stealth grows with height limitations
- Beginners who want significant yield improvements
- Creating even canopies for LED lights with limited penetration
- Sea of Green (SOG) or Screen of Green (SCROG) methods
Common Mistakes to Avoid
Bending Too Aggressively
Forcing stems to bend too far too quickly can cause snapping. Always bend gradually over several days.
Using Harsh Materials
Wire or string without padding can cut into growing stems. Use soft materials or pad wire ties.
Tying Too Tightly
Ties that are too tight restrict growth and can girdle stems. Leave room for stems to expand.
Starting Too Late
Beginning LST when plants are older makes stems less flexible and more likely to snap.
Recovery Time: Minimal to none. Plants typically show new growth patterns within 1-2 days.
Topping
Intermediate
What is Topping?
Topping is a high-stress training technique that involves cutting off the main growing tip (apical meristem) of the cannabis plant. This removal breaks apical dominance and forces the plant to develop two main colas from the nodes below the cut, effectively doubling your main cola count.
Step-by-Step Guide
- Wait for the right time: Plant should have 3-5 nodes (typically 2-3 weeks old).
- Prepare your tools: Use sharp, clean scissors or pruning shears (sterilize with alcohol).
- Identify the cut location: Find the main stem's growing tip above the 3rd or 4th node.
- Make a clean cut: Cut the main stem just above the highest node you want to keep. Make a clean, 45-degree angle cut.
- Allow recovery: Give the plant 3-7 days to recover before any additional training.
- Optional - Top again: Once new growth has established (typically 1-2 weeks), you can top each of the new main shoots to create 4 main colas.
Pro Tips
- Top in the morning when plants are fully hydrated
- Avoid topping during pre-flower or flowering stages
- Keep a close eye on plants in the days after topping for signs of stress
- Don't fertilize heavily immediately after topping
- Combine with LST to expose the new growth to light evenly
- "FIM" instead (see FIMming technique) if you want 4 main shoots from one cut
Ideal For
- Photoperiod plants with adequate vegetative time
- Creating bushier plants with multiple colas
- Controlling plant height in limited spaces
- Maximizing yields from fewer plants
- Preparing plants for SCROG or mainlining techniques
Before vs After Topping
Before
- Single main cola (apical dominance)
- Christmas tree shape
- Vertical growth focused
- Side branches smaller and less developed
After (2+ weeks)
- Two main colas of equal size
- Bushier, more horizontal growth
- Enhanced side branch development
- More even canopy
Common Mistakes to Avoid
Topping Too Young
Plants need at least 3 nodes and a strong root system to recover properly from topping.
Using Dirty Tools
Unsterilized cutting tools can introduce pathogens. Always clean with alcohol before use.
Cutting Too Low
Removing too much growth stresses the plant unnecessarily. Only remove the top growth tip.
Topping Autoflowers
Most autoflowering plants don't have enough time to recover properly from topping.
Recovery Time: 3-7 days for initial recovery. 1-2 weeks to see new growth pattern established.
FIMming (F*ck I Missed)
Intermediate
What is FIMming?
FIMming is a high-stress training technique similar to topping, but instead of removing the entire growth tip, you remove approximately 75-80% of it. The name "FIM" comes from "F*ck I Missed" when growers attempting to top accidentally cut only part of the growth tip and noticed it resulted in 3-4 new tops instead of 2.
Step-by-Step Guide
- Wait for the right time: Plant should have 3-5 nodes (typically 2-3 weeks old).
- Prepare your tools: Use sharp, clean scissors or your fingernails (pinching method).
- Identify the target: Locate the newest growth at the top of the plant.
- Make the cut: Instead of cutting the entire tip, remove about 75-80% of the newest growth, leaving the bottom portion intact.
- Scissors method: Cut across the newest growth, leaving about 20-25% at the base.
- Pinch method: Pinch between thumb and forefinger, removing most but not all of the new growth.
- Allow recovery: Give the plant 3-7 days to recover before additional training.
- Observe new growth: Within 1-2 weeks, you should see 3-4 new shoots developing from the FIMmed site.
Pro Tips
- The pinch method often yields more consistent results than cutting
- FIM when plants are well-watered and unstressed
- Results can be somewhat unpredictable – sometimes you'll get 2 tops, sometimes 4
- Combine with LST after recovery to spread the new tops for better light exposure
- FIMming is slightly less stressful than topping as it removes less material
- Can be performed multiple times on the same plant for more tops
Ideal For
- Photoperiod plants with adequate vegetative time
- Creating multiple main colas with a single cut
- Growers who want more tops than topping but less stress than manifolding
- Preparing plants for SCROG setups
- Situations where recovery time needs to be minimized
FIMming vs. Topping
FIMming
- Results: 3-4 new tops
- Recovery: Slightly faster (3-5 days)
- Stress level: Moderate high-stress
- Predictability: Less predictable results
- Growth pattern: More compact, less height reduction
Topping
- Results: 2 new tops
- Recovery: Slightly longer (5-7 days)
- Stress level: Higher stress
- Predictability: More predictable results
- Growth pattern: More spread out, greater height reduction
Common Mistakes to Avoid
Removing Too Much
Cutting too deeply turns a FIM into a topping, resulting in only 2 new shoots instead of 3-4.
Removing Too Little
Not removing enough of the growth tip may result in the plant continuing with single-cola growth.
FIMming During Flowering
Never FIM during the flowering stage as it will significantly reduce yields and stress the plant.
Expecting Exact Results
FIMming is inherently less precise than topping. Expect some variability in the number of new shoots.
Recovery Time: 3-5 days for initial recovery. 1-2 weeks to see the full development of new shoots.
SCROG (Screen of Green)
Intermediate
What is SCROG?
Screen of Green (SCROG) is a training technique that uses a horizontal screen or net positioned above the plants. Branches are woven through the screen to create a flat, even canopy where all bud sites receive direct light. This maximizes yield in a limited space and with a limited plant count.
Step-by-Step Guide
- Set up the screen: Install a screen (chicken wire, plastic trellis net, etc.) 30-40cm (12-16 inches) above the plant containers.
- Grow plants to screen height: Allow plants to grow until they reach the screen (usually 3-4 weeks of veg).
- Begin screen training: As branches grow through the screen, gently tuck them under adjacent screen squares, directing them toward empty areas.
- Fill the screen: Continue tucking branches horizontally until 70-80% of the screen is filled with an even plant canopy.
- Switch to flower: Once the screen is adequately filled, switch to flowering light cycle (12/12).
- Early flower maintenance: Continue tucking branches for the first 2-3 weeks of flowering (stretch phase).
- Allow vertical growth: After stretch, allow buds to grow upward through the screen toward the light.
Pro Tips
- Use 5×5 cm to 10×10 cm (2×2 to 4×4 inch) screen holes for easy training
- Top or FIM plants 1-2 weeks before they reach the screen to promote more branches
- Defoliate under the canopy once the screen is filled to improve airflow
- Keep the screen easily removable for plant maintenance
- Consider a second screen 20-30 cm above the first for support during late flowering
- Space plants further apart than usual (one plant per 60×60 cm / 2×2 ft is common)
Ideal For
- Maximizing yield in limited grow spaces
- Growing areas with height restrictions
- Legal grows with plant count limitations
- Optimizing efficiency with a single light source
- Photoperiod plants with longer vegetative periods
- Creating uniform, manageable canopies
SCROG Setup Requirements
Screen Material Options
- Plastic trellis netting: Flexible, reusable, easiest to work with
- Chicken wire: Sturdy but harder to manipulate
- String grid: DIY option using string and a frame
- Metal mesh: Most durable but least flexible
Frame Construction
- PVC pipes: Lightweight, inexpensive, easy to customize
- Wood frame: Sturdy and stable
- Tent poles: Can attach directly to grow tent poles
- Adjustable height: Use rope ratchets or adjustable poles
Additional Tools
- Soft plant ties: For guiding stubborn branches
- Small scissors: For selective defoliation
- Pipe cleaners: For securing branches to the screen
- Support poles: For heavy colas in late flowering
Common Mistakes to Avoid
Switching to Flower Too Early
The screen should be 70-80% filled before flowering. Switching too early leaves empty spaces.
Placing Screen Too High
If the screen is too high above pots, plants stretch unnecessarily to reach it.
Overcrowding Plants
Too many plants under one screen creates competition and management difficulties.
Stopping Training Too Soon
Continue tucking branches during the first 2-3 weeks of flower stretch for best results.
Vegetative Time Required: 4-6 weeks to properly fill a screen (strain-dependent).
Mainlining (Manifolding)
Advanced
What is Mainlining?
Mainlining (also called manifolding) is an advanced training technique that creates a symmetrical plant structure with a central "manifold" from which all main branches emerge at the same height. This results in equal energy distribution to each cola, producing uniform bud development and maximizing yields.
Step-by-Step Guide
- Begin with a young plant: Wait until the plant has 5-6 nodes (typically 3-4 weeks old).
- First topping: Top the plant above the 3rd node, removing everything above it.
- Remove lower growth: Remove all growth below the 3rd node, including all fan leaves and branches.
- LST the remaining branches: Tie down the two remaining top branches horizontally, creating a "Y" shape.
- Allow growth and recovery: Let the plant recover and grow 3-4 nodes on each branch (7-10 days).
- Second topping: Top each of the two main branches to create 4 main shoots.
- Continue the pattern: For 8 colas, allow growth and top again. For 16, repeat once more.
- Final training: Arrange all branches outward like a spokes on a wheel using LST.
- Switch to flower: Once the structure is established and plants have recovered, switch to flowering.
Pro Tips
- Maintain perfect symmetry at each step for equal energy distribution
- Give adequate recovery time between toppings (7-10 days minimum)
- Completely clear the area below the manifold for better air circulation
- Use bamboo stakes or a SCROG screen for support as buds develop
- 8 colas is often the sweet spot between yield and vegetative time
- Keep detailed notes on timing for each plant to improve future grows
Ideal For
- Experienced growers comfortable with high-stress techniques
- Photoperiod plants with longer vegetative periods (adds 2-4 weeks)
- Grows where maximizing yield per plant is essential
- Creating visually striking, perfectly symmetrical plants
- Growing spaces with good height clearance
- Growers seeking consistent, predictable bud development
Mainlining Cola Progression
Common Mistakes to Avoid
Rushing The Process
Insufficient recovery time between toppings stresses plants and slows overall growth.
Asymmetrical Training
Allowing one side to dominate defeats the purpose of equal energy distribution.
Keeping Lower Growth
Failing to remove all growth below the manifold diverts energy from main colas.
Too Many Colas
Going beyond 8-16 colas often results in smaller buds and diminishing returns.
Vegetative Time Required: 6-8 weeks for a complete 8-cola manifold structure.
Recovery Periods: 7-10 days after each topping session.
Strategic Defoliation
Intermediate
What is Strategic Defoliation?
Strategic defoliation is the selective removal of fan leaves to improve light penetration to lower bud sites and enhance air circulation within the canopy. Unlike other training methods that focus on branch structure, defoliation targets the leaves to redistribute energy and create an optimal growing environment.
Step-by-Step Guide
- Vegetative defoliation: During mid-to-late veg, remove large fan leaves that shade potential bud sites.
- Pre-flower defoliation: 1-2 days before switching to flower, remove 20-40% of fan leaves, focusing on:
- Leaves that shade bud sites
- Leaves pointing toward the center of the plant
- Older, larger fan leaves at the bottom
- Day 21 defoliation: Three weeks into flowering (after stretch), perform a second round of defoliation:
- Remove leaves blocking light to developing buds
- Clear out crowded areas to improve air circulation
- Target leaves touching each other
- Day 42 defoliation (optional): For longer flowering strains (10+ weeks), a light final defoliation.
- Maintenance defoliation: Throughout flowering, remove yellowing or dying leaves.
Pro Tips
- Never remove more than 20-40% of leaves in a single session
- Allow 3-7 days recovery time after significant defoliation
- Focus on removing leaves that touch each other
- Target leaves that don't receive direct light (they're net energy consumers)
- Keep all top canopy leaves that receive direct light
- Combine with LST or SCROG for maximum effect
- Use pruning scissors for clean cuts; don't tear leaves
Ideal For
- Dense, bushy strains with heavy foliage
- Plants with overlapping foliage that blocks light penetration
- Humid environments where air circulation is crucial
- SCROG setups to maximize light to the canopy
- Indoor grows with limited light penetration
- Photoperiod plants with adequate recovery time
Leaf Selection Guide
Leaves to Remove
- Large fan leaves shading bud sites
- Lower fan leaves receiving minimal light
- Leaves pointing inward toward plant center
- Overlapping leaves in crowded areas
- Yellowing or damaged leaves
- Leaves touching soil or growth medium
Leaves to Keep
- Top canopy leaves receiving direct light
- Young, developing leaves
- Leaves directly attached to developing bud sites
- Most sugar leaves (small leaves in bud formations)
- Healthy leaves without shadowing issues
- Leaves providing balanced coverage
Common Mistakes to Avoid
Excessive Removal
Taking too many leaves at once can shock the plant and stunt growth. Stay under 40% removal.
Defoliating Too Young
Young plants need their leaves for development. Wait until they're established with 5-6 nodes.
Late Flower Defoliation
Heavy defoliation after week 6 of flower can reduce yields. Focus on maintenance only.
Removing Sugar Leaves
Small leaves growing from buds contribute to bud development. Leave these intact.
Recovery Time: 3-5 days after moderate defoliation. Schedule defoliation sessions around this recovery period.
Additional Resources
Recommended Equipment
- Soft plant ties: For LST without damaging stems
- Sharp pruning scissors: For clean cuts during topping/FIMming
- Plastic trellis netting: For SCROG setups (5×5 cm or 10×10 cm grid)
- Garden wire with coating: Alternative for LST ties
- Small bamboo stakes: For support and anchor points
- Plant yo-yos: For supporting heavy colas during late flowering
Training Timeline
- Seedling (1-2 weeks): No training, focus on establishment
- Early Veg (2-3 weeks): Begin LST, first topping/FIMming
- Mid Veg (3-5 weeks): Continue LST, secondary topping, begin SCROG
- Late Veg (5-8 weeks): Complete manifold structure, fill SCROG screen
- Early Flower (weeks 1-3): Final adjustments, strategic defoliation
- Mid-Late Flower: Support heavy buds, minimal intervention
Technique Combinations
- Topping + LST: Creates bushy plants with multiple tops
- FIMming + LST: More tops with less recovery time
- Mainlining + SCROG: Perfect canopy with equal cola development
- SCROG + Defoliation: Maximizes light to bud sites
- LST + Defoliation: Simple but effective yield increase