How To Remove Fan Leaves Using The Schwazzing Technique

Skip to content

Homepage Articles Flowering Stage High-Stress Training Versus Moderate Pruning Methods for Cannabis Plants

High-Stress Training Versus Moderate Pruning Methods for Cannabis Plants

• Published: April 8, 2019

(* Article updated August 10th, 2024.)

Curious how to prune your cannabis for heavier yields without damaging your crop?

Effective pruning can lead to heavier, healthier buds without harming your crop.

For example, in the early growth stage, you can prune your cannabis plants once they start to become bushy.

• Vegetive Stage Pruning – What to look for when planning to remove fan leaves during veg:
• Watch our Grow POV video: Pruning Before Bloom
• Flowering Stage Pruning – Remove fan leaves during flowering in much the same way you do during veg…
• Pruning Tips
• Is HST (High-Stress Training) Worth It For Cannabis?
• Is the Schwazzing Technique Worth It?
• How Exactly Does Schwazzing Work?

Vegetive Stage Pruning – What to look for when planning to remove fan leaves during veg:

• Prune leaves at the bottom of the plant that receive little light.
• Cannabis fan leaves that create shadows over budding sites should be pruned to increase light penetration throughout the canopy, rather than just the tops.
• Prune fan leaves that are growing inward toward the plant.
• Remove bud sites that are lower down on the plant so energy can be redirected to the bud sites closer to the top.
• Prune dead or dying leaves so the plant can direct its energy toward new growth.

Watch our Grow POV video: Pruning Before Bloom

Watch our Grower POV video, where we share insider tips on setting up drip irrigation – Grower POV: Setting Up Drip Irrigation.

Flowering Stage Pruning – Remove fan leaves during flowering in much the same way you do during veg…

• Prune away large leaves that are overshadowing bud sites, as well as dead or dying fan leaves.
• Prune in intervals, giving at least a couple weeks between each session. Pruning every day can forsake your plants to a perpetual state of shock that may impede growth rather than encourage it.

Pruning Tips

When pruning your cannabis, always remember…

• Soak your tools in a 20% bleach solution to prevent the spread of contaminants.
• Look for sharp pruning shears or scissors that won’t damage your plants.
• Invest in pruning scissors and pruning snips for more precise cuts.
• Wear gloves and eye protection throughout the pruning process.

Pro Tip: ​​Lollipopping

Pro Tip from The CCI Black Book – The Definitive Roadmap for Successful Commercial Cannabis:

Cannabis industry expert Jack Whipple recommends lollipopping your plants on days 7-10 during the veg stage. Discover more cultivation tips and visit this page to download a free chapter of The CCI Black Book. The result of experiments across millions of square feet of commercial gardens, this proven roadmap reveals how top growers consistently yield 3-4 lbs of top-quality flower per light.

With an in-depth understanding of pruning, you’ll be well equipped to maximize your cannabis yields with the right technique for your grow.

For other recommended growing techniques, subscribe to the Advanced Nutrients newsletter.

Is HST (High-Stress Training) Worth It For Cannabis?

In recent years, growers have devised many methods for defoliating cannabis, including lollipopping, topping, fimming, and schwazzing.

These methods are often referred to as high-stress training (HST).

There are various reasons growers believe these extreme pruning methods work…

Theories Behind HST

1. Defense Mechanism: Some claim HST techniques trigger a fight-or-flight defense mechanism in cannabis, inciting stronger flowering as plants try to survive by making themselves undesirable to a perceived attacker.
2. Increased Air Exposure: Others claim that the increased air exposure caused by removing fan leaves results in the plants pushing bigger buds to be pollinated, just as they would in the wild.

 

The truth is that these are all just theories, none of which have been backed by actual scientific research.

No one knows exactly why heavy defoliation during flowering may cause bigger bud growth. And the fact is that these extreme methods can be risky.

Is the Schwazzing Technique Worth It?

Many growers have found success using the schwazzing technique of removing fan leaves. To put it simply, schwazzing is an extreme form of defoliation that some cultivators rely on to promote productive flowering.

However, it is not recommended for the beginner or amateur cannabis grower.

When performed incorrectly, schwazzing and other forms of extreme leaf defoliation can cause significant harm, including complete crop failure.

You see, your plants’ leaves play a critical role in your crop’s development.

Here are some of the key functions they serve:

• Leaves are the site of transpiration, where CO2 is taken in and oxygen and water vapor are released.
• Leaves are integral to the production and transport of crucial hormones needed for flowering.
• Essential carbohydrates are produced in the leaves through photosynthesis.
• Carbohydrates, water, and other critical nutrients are stored in the leaves.

 

With schwazzing, the idea is to cause some level of damage and stress to the plant by removing its leaves, but afterward provide a precise regimen of macro, secondary, and micronutrients to replace all the nutrition lost through the heavy defoliation.

Again, this all sounds good in theory.

However, in order for the schwazzing process to be successful, you have to precisely dial in a number of factors:

• Air quality
• Temperature
• Humidity
• Lighting
• Air flow
• CO2 Levels
• Grow medium

 

Let’s take a deeper look at why expert growers often use this high-stress training method on their cannabis plants.

How Exactly Does Schwazzing Work?

The schwazzing technique and its unique moniker were developed by Joshua Haupt, a Colorado-based cultivation expert who introduced schwazzing in his 2015 book, Three A Light.

The book’s title comes from Haupt’s claim that growers who follow the methods outlined within its pages – including schwazzing – can pull yields of three pounds per light.

Schwazzing involves stripping all cannabis fan leaves beneath the top two or three nodes at two key times:

Once at the start of the bloom phase, and again at the beginning of the third week of bloom.

As with other methods of heavy defoliation, the idea is to increase yield by providing maximum light penetration and reducing or eliminating shade spots, while redirecting the plant’s energy to the top budding sites.

Other benefits of schwazzing include:

• Helping to fight pests by eliminating hiding spots.
• Reducing microclimates that can harbor molds and mildews.
• Slowing stretch in some genial pools, which can allow for lower canopies to form – a plus for many growers.

 

Clearly, the schwazzing method has worked well for Haupt, who has said he and his team have surpassed four pounds per light in the years since releasing the book.

Schwazzing is an expert-level technique that should only be attempted by highly experienced cannabis growers working under finely tuned conditions.

If you are interested in giving schwazzing a shot and tend to run the same genetics each cycle, you can test the technique on a few plants to see how your strain reacts before defoliating the rest of your grow.

For more practical cultivation advice that will help you get even more from your crops, subscribe to our newsletter.

Categories

All Topics Company News Product Guides Feeding Tips Beginner Tips Pests & Diseases Vegetative Stage Flowering Stage Set-up & Equipment Harvesting Commercial Grower

Latest Posts

The Cannabis Profit Margin Paradox: 5 Hard Truths Every Cultivator Needs to Hear

The Advanced Nutrients’ 8th-Generation Elite Series: Our Most Powerful Commercial Cultivation System Yet

Advanced Nutrients Debuts Elite Commercial Package at CannMed 2026

2025: The Year Advanced Nutrients Redefined Cannabis Cultivation

5 Hard Truths from Colton Luther Every Texas Grower Needs Right Now

Advanced Nutrients Launches Czech Website to Support Growers Under New Cannabis Laws

About the Author

The Advanced Nutrients Team

Since 1999, Advanced Nutrients has been committed to educating the community and bringing the most up-to-date knowledge to the forefront of grows across the globe. Every article you read here has been curated by Advanced Nutrients’ industry experts, so you can continue raising your bud weight… and your reputation.

Previous Post

Next Post

The Cannabis Profit Margin Paradox: 5 Hard Truths Every Cultivator Needs to Hear

The Advanced Nutrients’ 8th-Generation Elite Series: Our Most Powerful Commercial Cultivation System Yet

Get More Articles Chock-Full of Cultivation Tips, Tricks, and Strategies Delivered Straight To Your Inbox

Sign up for our free newsletter and receive more relevant cannabis cultivation content right in your inbox! Subscribe below.

Need Help Growing? Search Why Do I Need To Shake Nutrients in Their Bottle Before Mixing Them?

Over time, components within the nutrients settle on the bottom of the bottle. When you pour a bottle without shaking it, you can potentially be pouring out an unbalanced solution. Shaking up the nutrient bottle ensures you are pouring the right blend into your reservoir, giving your crops the nutrition they need.

Can I Mix Products From Different Manufacturers?

Usually, it’s not a problem. But some products are incompatible with each other and can damage your plants when they’re used together. For example, bloom boosters with high PK numbers or low-grade silica products can destabilize your nutrient mix and cause nutrient lockout.

Nutrient manufacturers design their products to be used with each other. In doing so, they include specific portions of each nutrient in each product, so crops receive the right nutrition through each stage of the grow cycle. When you stick with one manufacturer, you don’t have to worry about inadvertently destabilizing your nutrient mixture. One example of why you need to stick with only one manufacturer’s products is Advanced Nutrients’ pH Perfect line. These products are designed to keep your crops’ root zone within a specific pH range. When you use them alongside products from another manufacturer, we can’t guarantee your root zone will maintain its optimal pH level.

Is There An Easy Way To Know How Much of Each Nutrient I Need To Add To My Garden?

 

Yes! If you’re growing with Advanced Nutrients products, you can use our easy nutrient calculator to generate the correct nutrient chart for your crops in seconds. Check out Advanced Nutrients’ nutrient calculator here. Another great resource is our library of free custom-growing recipes. Try our expert grower-tested nutrient schedules here.

You can also download our official BudLabs app to generate nutrient schedules and receive real-time notifications for specific tasks, including feeding your crops.

Where Can I Buy Advanced Nutrients?

If you are a grower, visit this link to find the closest Advanced Nutrients Authorized Retailer. If you are a retailer, visit this link to identify our official distributors.

Do You Offer Customer Support?

Our greatest passion is growing great cannabis—and helping other growers do the same. That’s why we offer complimentary cultivation support 24/7 from Monday to Friday and from 9 AM until 7 PM PST on Saturday… With the same level of advice licensed producers would pay consultants tens of thousands of dollars to unlock.Just call 1-800-640-9605 or email [email protected]. For Spanish-speaking growers, email [email protected].

Do You Have A Product Guarantee? Yes! If for any reason you are not absolutely thrilled with the results you achieve when you use our products, just bring the unused portion, along with your original sales receipt, back to the place of purchase within six months, and ask for your money back. Find out more about our Grower Guarantee here. What Is pH Perfect®?

Advanced Nutrients has spent many thousands of man-hours developing a technology that automatically balances your pH for you — putting it in the “sweet spot” and holding it there for one week.

And the technology is so “smart” that it can account for many of the aforementioned variables in your grow room. Our proprietary pH buffering agents and stabilizing mechanisms became the foundation of a new system aptly called pH Perfect® Technology. Learn all about it here.

Change Region

If your country/region is not listed on this page, please find your local Contact Details, Authorized Retailer and Grower Support on our Global Site.

United States

EnglishSpanish

Canada

English

EN Commercial Products 8th Generation (NEW) For Commercial Cultivators For Home Growers For Organic Growers For Coco Growers All Products Secret Menu Feeding Nutrient Calculator Official Feeding Charts Commercial SOPs Recipes from the Community Grower Support Articles Where To Buy Authorized Retailers Authorized Distributors Become An Authorized Retailer Cultivator Spotlights Contact Us

• EN English English

• EN English English

• EN English English