Name: GL420W LED Grow Light by Treegers — 420W Full-Spectrum LED Fixture for 1.2m Canopy
Brand: Treegers
SKU: TRG-LED-FIX-420W
Price: 664.95 AUD
Availability: InStock

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The Treegers GL420W is a 420W, six-bar LED grow fixture built for serious 1.2 x 1.2m canopy coverage. It pumps out 1155 μmol/s PPF at 2.8 μmol/J fixture efficacy — numbers that compete with lights costing twice as much — while running completely silent thanks to passive cooling. No fans, no noise, no fuss. Just hang it, plug it in, and start pushing your plants.

1155 μmol/s PPF Output Serious photon delivery across the full canopy — veg and bloom, start to finish.

2.8 μmol/J Fixture Efficacy Squeezes more usable light out of every watt. Your power bill will thank you.

Passive Cooling — Zero Noise High-grade heat sinks do the work. No fans, no maintenance, no racket.

IP66 Rated Full protection against dust and high-pressure water jets. Built for real grow room conditions.

Full-Spectrum Fusion 4000K, 5000K and 660nm diodes combined to nail every growth stage from seedling to harvest.

60,000+ Hour Lifespan That is years of growing. Buy it once, run it into the ground (not literally).

Tech Specs

Power Draw: 420W ±5%

PPF Output: 1155 μmol/s

Fixture Efficacy: 2.8 μmol/J

Diode Efficacy: Up to 4.2 μmol/J

Coverage Area: 1.0 x 1.0m – 1.2 x 1.2m

Input Voltage: 120–277V / 50–60Hz

Dimming: 0–100% (via compatible controller)

Light Distribution: 120°

Thermal Management: Passive Cooling

Ingress Protection: IP66

LED Bars: 6-bar integrated design

LED Lifetime: 60,000+ hours

Dimensions: 700 x 680 x 42mm

Weight: 5.08kg

Spectrum: Full-Spectrum Fusion (4000K / 5000K / 660nm)

Certifications: CE, UKCA, RCM, RoHS, SAA

Warranty: 3 Years

Product Code: TGL0002

What's in the Box

1x GL420W LED Fixture 6 LED bars, integrated driver and frame — ready to hang.

1x Power Cable 1.8m cable with plug and Jnicon connector included.

2x Stainless Steel Hangers Cable hangers included for a clean, secure hang above the canopy.

1x User Guide Clear setup instructions for first-timers and seasoned growers alike.

Controller Required — Don't Skip This

The GL420W does not dim on its own — you need a compatible controller to unlock dimming.
Treegers Precise T-Dimmer (0–10V) is the most affordable option for single-light setups.
The Treegers Growcast connects multiple fixtures and lets you run schedules and automation.
Any universal 0–10V controller will also work if you already have one in your setup.
Not sure which to grab? Hit up The Grow Guys and we'll sort you out before you buy.

How to Set Up the GL420W

1

Hang it at the right height — Start with the fixture 40–60cm above the canopy for veg. Drop to 30–40cm in flower if your plants can handle the intensity. Use the included stainless steel hangers and a ratchet system for easy height adjustment.

2

Connect your controller — Plug the Precise T-Dimmer or Growcast into the fixture's control port. Without this, the light will run at full power only. For new growers, the Precise T-Dimmer is a simple, affordable place to start.

3

Start low, ramp up — Don't blast seedlings or clones at 100%. Start at 40–60% intensity and raise it as your plants develop root mass and leaf area. Watch for bleaching or tip curl as signs you're pushing too hard too soon.

4

Match your photoperiod to the stage — 18/6 for veg, 12/12 for flower if you're running photoperiod plants. Autoflowers can run 18–20 hours of light all the way through. A timer or the Growcast handles scheduling automatically.

5

Ensure airflow around the fixture — Passive cooling works best when air is moving through your space. A clip fan or circulation fan pulling air over the heat sinks will help the GL420W run at its most efficient.

6

Clean the bars periodically — A soft dry cloth or a puff of compressed air keeps the diode surface clear and maintains output efficiency over time. Always power off and let the fixture cool before cleaning.

Pairs Well With

Treegers Precise T Dimmer

The simplest way to unlock full dimming control on the GL420W. Plug in, dial in.

Treegers Growcast Controller

Link multiple fixtures and run automated light schedules from one controller.

Treegers Fixture Link Cable

Running multiple GL420W fixtures? One Fixture Link Cable per additional light lets the Growcast or T Dimmer control the whole chain.

Clip Fans and Air Circulation

Passive cooling works better with airflow. A clip fan over the fixture keeps temps in check.

Treegers Quantum PAR Meter

Verify your GL420W is delivering the PPFD your canopy needs at the height you've set — stop guessing, start measuring.

Hydroponic Nutrients

More light means more feed demand. Make sure your nutrient program can keep up with the canopy.

Frequently Asked Questions

Does the GL420W come with a dimmer or controller?

No — a controller is sold separately. To dim the GL420W, you need a Treegers Precise T-Dimmer (0–10V), the Treegers Growcast, or any compatible universal 0–10V controller. Without one, the fixture runs at full output only.

What size grow space does the GL420W cover?

The GL420W covers a minimum of 1.0 x 1.0m and a maximum of 1.2 x 1.2m, making it purpose-built for a standard 1.2m square tent. Running it over a smaller area increases intensity per square metre, which can benefit heavy-feeding flowering plants.

Is passive cooling actually enough for a 420W light?

Yes — at 2.8 μmol/J efficiency, the GL420W converts most of its energy into light rather than heat, which means the thermal load on the heat sinks is lower than you'd expect. Treegers uses high-grade aluminium heat sinks across the six-bar design to spread and dissipate heat passively. Ensuring adequate airflow in your tent keeps everything running optimally.

Can I use the GL420W for both vegetative and flowering stages?

Yes — the Full-Spectrum Fusion design combines 4000K, 5000K, and 660nm diodes, which supports strong vegetative growth and heavy flowering in a single fixture. There is no need to swap lights between stages.

Can I run multiple GL420W fixtures from one controller?

Yes — the Treegers Growcast supports multiple fixture connections using Treegers Fixture Link Cables. The Precise T-Dimmer can also daisy-chain multiple fixtures. Contact The Grow Guys if you're planning a multi-light room and we'll confirm the correct cable configuration.

Is the GL420W suitable for outdoor or greenhouse use?

Yes — the IP66 rating means it handles full dust ingress protection and high-pressure water jets, making it well-suited for greenhouse environments as well as indoor grow rooms. It's not designed for direct exposure to rain or submersion.

What is the warranty on the GL420W?

The GL420W comes with a 3-year manufacturer warranty from Treegers. The LED bars are rated for 60,000+ hours of operational life. If something goes wrong within that warranty period, contact us and we'll work through it with you.

420 Watts. Zero Noise. All Yield.

The Treegers GL420W is a set-and-forget LED fixture built to run hard for years. Questions before you buy? The Grow Guys team is here to help.

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GL420W LED Grow Light by Treegers — 420W Full-Spectrum LED Fixture for 1.2m Canopy