Heavyweight autoflower yields: from myth to reality

Legal Disclaimer: This article is intended for educational purposes only. It does not constitute legal advice and should not be interpreted as encouragement or endorsement of cannabis cultivation in jurisdictions where it is not permitted by law. Readers are responsible for understanding and complying with all applicable laws in their respective locations.

Recent advancements in autoflower seed genetics and cultivation practices have significantly enhanced the performance potential of these plants. When paired with refined hydroponic techniques, some growers have reported achieving dry yields of approximately 1kg under controlled conditions.

One approach involves multiple rounds of intensive defoliation (‘schwazzing’) during the life cycle, which may extend the plant's development period from an average of 75 days to approximately 110–120 days. This extended timeframe can support increased floral development and overall plant mass.

When implemented alongside high-efficiency LED lighting systems, under-canopy illumination, SCROG techniques, and precise hydroponic management, this method has resulted in notably high yields. Documented case studies detail harvests exceeding 1.3kg and 1.4kg, accompanied by step-by-step visual and technical records.

Below we review this new ‘420autoflower’ grow method and explain how the principles may be applicable the principles in your own grow environment.

Meet 420Autoflower, US-based cannabis grower

420autoflower is an expert USA hydroponics pro. He developed his own proven technique to push the best cannabis seeds to their absolute limits. His technique involves:

• 3 or 4 severe defoliations (‘schwazzing’) for each plant.
• Use of supercropping to completely flatten the plant and place under a SCROG screen.
• Expert hydroponic nutrient control. Drip fed in a 10x10cm (4” x 4”) glasswool cube on top of a 23cm x 15cm (9”x6”) glass wool block.
• LED lighting above and below the SCROG net.

“I’m constantly defoliating starting from day 20 but I do my first leaf schwazz when I’m prepping them for the SCROG net. I’ll do 2 to 3 more during flower but it all depends on how much foliage each individual plant grows.

The first Critical Orange Punch I just posted required 4 schwazzings to get her to where she is and the other Critical Orange Punch only needed 3 rounds, so the amount of pruning varies from plant to plant.”

The setup: premium genetics in hydroponic system

Since 420autoflower first showed his unique grows online many other growers have copied his method and have also produce the same crazy results, if not quite on the same scale as 420autoflower himself. You too could use this grow method and see your heaviest harvests yet. Even if you can’t grow with hydroponics, you can still apply the basic principles to a soil or coco fibre grow:

• Regular schwazzing. This helps stress the plant and extends life cycle to ~115 days.
• Use of SCROG method. Supercropping (crushing between thumb & finger) allows the entire canopy to be flattened for the SCROG screen to be lowered right down.
• Expert use of LED lighting throughout - keeping blooms in the optical sweet spot.
• Use of under-canopy lighting. Very effective but rarely practiced.
• Use of large, aerated grow containers, e.g. 30+ litres / 6+ gal aerated containers (felt sacks, air pots or similar).
• Ensuring plants remain in the nutrient sweet spot from weed seed to harvest. Avoid over/under feeding. Soil growers - Excess water should be prevented, soil moisture meters can help.

Plants may exhibit optimal results when grown with some proven high-performance genetics. Bag-seed or budget seed won’t necessarily cut it if you’re looking for epic results. Invest in some proven high-yield genetics from an established seedbank you trust. The ongoing seed sale is a great place to start if you’re on a tight budget.

The approach outlined and the results are pretty much guaranteed. The goal is to keep your plant free from over/under feeding. Use of SCROG should ensure numerous bloom points. Maintaining optimal conditions will help to keep the plant growing healthily under the LED using the SCROG to ensure numerous blooms.

Without doubt, some bravery is required to use such extreme schwazzing (50% or more leaf removal) 3 or 4 times.

However, the skilled growers who are prepared to take a few new risks and explore innovative plant training strategies can easily be slaying their previous personal bests in the grow room.

The results: 1KG+ dry yields from autoflowers

On both these XXL yielding autoflower seed grows 420autoflower also gave top marks for potency, aroma and effect. As any experienced gardener knows, allowing their plants to thrive continuously from marijuana seed to harvest maximises cannabinoids & terpenes. Pushing the genetic potential of the plant to the limit gives you the best results.

Bag appeal using this grow method ensures really frosty blooms with all the buds ripening under ideal PPFD light intensities thanks to the effective use of the SCROG screen.

420autoflower grows for quality and prides himself on the quality and dankness of his buds. Achieving insane yields doesn’t mean reduced bud quality. So long as you start with quality cannabis seeds, your final bud potency/flavour is genetically assured. Controlling your grow and not being afraid to supercrop, SCROG and regularly schwazz will allow you to break your personal-best harvest records.

One key piece of advice from 420autoflower is to get autos under the SCROG net 3-5 days after the first pre-flower pistils. If growing photoperiod, allow 10 days of bloom before lowering the SCROG screen. Timing is key, since this can increase the potential number of bloom points to develop under the flattened canopy.

“I’m sure the stress I put on my plants does slow them down a bit but it’s also a known fact that running hydro properly will increase the plants veg and preflower time. It must have something to do with the consistent nutrients they get every 4-5 hours.

If I hook them up to automated fertigation at day 21 my preflower pistils don’t usually appear until around day 45, giving me a little extra time to work the plant compared to your average soil grow. The 420autoflower scrog method is completely different from your typical scrog. People usually use scrog netting to even out a canopy (or cola support) but with the 420-method, the net is used for training only.

If you’re going for the 420-method timing is very important so it’s good to scrog out your autos 3-5 days after seeing your first preflower pistil or about 10 days after flip with photoperiod strains. This allows the last remaining stretch to be done under the net.

By keeping all your main branches pointing horizontal the energy will be diverted to the smaller nodes in the middle which helps create a nice canopy of colas.”

Final thoughts and key takeaways

The best modern autoflower seed varieties are a world away from the first generation low/medium yielding cultivars. Dutch Passion have used their decades of expertise to push autoflower genetics to the very edge of their limits.

THC levels are now routinely 20%+ and some of the more potent strains such as Auto Cinderella Jack, Auto Skywalker Haze, Auto SFV OG & Auto Lemon Kix can hit 25% THC.

The best auto strains match the potency of their feminised seed counterparts and in certain genetic lines can comfortably exceed them.

What may be more surprising to some growers is the astonishing yield potential that the best autoflower seed varieties now possess.

Being able to bloom under 20-24 hours of daylight already offers tremendous advantage to the most vigorous auto genetics. Being able to do that while extending the total grow life cycle to around 110-120 days offers the ultimate opportunity to those seeking maximum yields.

Original cannabis seed to harvest reports by 420Autoflower:

• Auto Critical Orange Punch 1.4Kg dry harvest
• Auto Daiquiri Lime 1.3Kg dry harvest