# What is schwazzing?

> Schwazzing is an aggressive defoliation schedule that strips almost every fan leaf at the start of flower and again around day 21. Proponents say it pushes light into bud sites; no controlled cannabis trial shows it raises yield or cannabinoids. GenetixBay's position is tuck, don't pluck: strip within reason if you must, never on stressed plants or autoflowers.

- Canonical: https://genetixbay.com/knowledge/answers/what-is-schwazzing.html
- Topic: Training · Type: Definition
- Evidence: Contested · Status: Draft: awaiting expert review
- Full article: [Defoliation and lollipopping: what to remove, when, and the evidence](https://genetixbay.com/knowledge/training/defoliation-lollipopping.md)
- Also asked as: What is schwazzing defoliation? | Should I strip all the leaves twice in flower? | Does schwazzing increase yield? | Day 1 and day 21 defoliation
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Short answer

[Schwazzing](https://genetixbay.com/knowledge/glossary/schwazzing.md) is a heavy defoliation schedule: strip almost every [fan leaf](https://genetixbay.com/knowledge/glossary/fan-leaf.md) at the start of flower, let the plant regrow for three weeks, and strip it again around day 21. No controlled cannabis trial shows it raises yield or [cannabinoids](https://genetixbay.com/knowledge/glossary/cannabinoid.md). *Contested*. GenetixBay's position is tuck, don't pluck.

## Why

The idea is that bare plants push light and energy into [bud sites](https://genetixbay.com/knowledge/glossary/bud-site.md) and get better airflow. The counter-argument is that leaves are the solar farm feeding the buds, and stripping them removes [photosynthetic](https://genetixbay.com/knowledge/glossary/photosynthesis.md) capacity.

The nearest controlled data are for ordinary [defoliation](https://genetixbay.com/knowledge/glossary/defoliation.md), not schwazzing. On large greenhouse plants, defoliation three weeks before harvest left flower and cannabinoid yield per plant unchanged and made cannabinoids more uniform [1]. At commercial density, yield per m² matched the control [2].

A [hemp](https://genetixbay.com/knowledge/glossary/hemp.md) study found early-flower defoliation raised total cannabinoid concentration while other timings didn't [3], but it simulated hail damage and may not transfer to indoor drug-type cannabis.

Airflow is a real benefit. Dense, humid interiors favour [bud rot](https://genetixbay.com/knowledge/glossary/botrytis.md) and [powdery mildew](https://genetixbay.com/knowledge/glossary/powdery-mildew.md) [4], though tucking and spreading branches often achieves the same.

Cultivars differ a lot. Some clones lose most of their leaves with no effect, or even grow faster; others suffer. Tuck vs strip is an open GenetixBay [Bay Trial](https://genetixbay.com/knowledge/glossary/bay-trials.md) question.

## The numbers

| | Schwazzing | Tuck-first (house) |
|---|---|---|
| Leaves removed | Nearly all fan leaves, twice | Only those that can't be tucked |
| Timing | Flower day 1 and about day 21 | Any time; light thinning around day 21 |
| Per session | Most of the leaf area | About 20–30% at most |
| Yield evidence | None for schwazzing | Defoliation neutral for yield [1][2] |
| Suits | Vigorous, healthy [photoperiods](https://genetixbay.com/knowledge/glossary/photoperiod.md) only | Every cultivar |
| [Autoflowers](https://genetixbay.com/knowledge/glossary/autoflower.md) | No | Yes |

## What to do

1. Tuck fan leaves under or behind bud sites first.
2. [Lollipop](https://genetixbay.com/knowledge/glossary/lollipopping.md) the lower third at the flip.
3. Remove only leaves you can't tuck that crowd a humid interior.
4. If you want to test schwazzing, run it on one plant beside a matched tucked clone and weigh the [dry yield](https://genetixbay.com/knowledge/glossary/yield.md).

## Common mistakes

- Schwazzing stressed, hungry or slow plants.
- Schwazzing autoflowers.
- Trying it first on an untested cultivar across the whole room.
- Stripping when the real problem is weak light.

## Related

- Full article: [Defoliation and lollipopping](https://genetixbay.com/knowledge/training/defoliation-lollipopping.md)
- Answers: [defoliating autoflowers](https://genetixbay.com/knowledge/answers/can-i-defoliate-autoflowers.md) · [increasing yield](https://genetixbay.com/knowledge/answers/how-to-increase-yield-indoors.md)
- Terms: [schwazzing](https://genetixbay.com/knowledge/glossary/schwazzing.md) · [defoliation](https://genetixbay.com/knowledge/glossary/defoliation.md) · [tucking](https://genetixbay.com/knowledge/glossary/tucking.md) · [lollipopping](https://genetixbay.com/knowledge/glossary/lollipopping.md)

## Follow-up questions

**Does schwazzing increase yield?** No controlled cannabis trial shows that schwazzing increases yield. The best data, on large greenhouse plants, found that ordinary defoliation three weeks before harvest left flower and cannabinoid yield per plant unchanged. Schwazzing goes much further, stripping almost all leaves twice. Some cultivars shrug it off and others suffer, so GenetixBay treats it as contested and prefers tucking leaves.

**Should I schwazz an autoflower?** No, don't schwazz an autoflower. Autoflowers run on a fixed countdown from germination and can't be vegged longer to regrow lost leaves, so stripping almost all their foliage twice costs yield they never recover. Tuck fan leaves away from bud sites and spread branches with low-stress training instead, removing only leaves that are damaged, dying or touching the medium.

**How is schwazzing different from lollipopping?** Schwazzing and lollipopping remove different parts of the plant. Lollipopping removes small shoots and leaves from the shaded lower third, growth that would only make airy larf, at or soon after the flip. Schwazzing strips nearly every fan leaf from the whole plant twice, on day 1 and around day 21 of flower. Lollipopping is mainstream practice; schwazzing is contested.

## Sources

1. Danziger N, Bernstein N, 2021. Shape matters: plant architecture affects chemical uniformity in large-size medical cannabis plants. Plants 10(9):1834. https://pmc.ncbi.nlm.nih.gov/articles/PMC8468686/
2. Danziger N, Bernstein N, 2022. Too dense or not too dense: higher planting density reduces cannabinoid uniformity but increases yield/area in drug-type medical cannabis. Frontiers in Plant Science 13:713481. https://doi.org/10.3389/fpls.2022.713481
3. Sandoval SM et al., 2024. Defoliation timing effects on phytocannabinoids in hemp (simulated hail). Industrial Crops and Products; MSc thesis version, Colorado State University. https://mountainscholar.org/bitstreams/a8421af5-2146-4d67-8751-397a58816f1b/download
4. Punja ZK, 2021. Emerging diseases of Cannabis sativa and sustainable management. Pest Management Science 77:3857–3870. https://pmc.ncbi.nlm.nih.gov/articles/PMC8451794/