Our Top Pick
The HLG 350R is the best LED grow light for most cannabis growers who flower in a 3x3 space or veg a 4x4. It pulls near 330 watts, runs Samsung LM301H diodes, and spreads light with a bar layout instead of a single hot center. The driver mounts on top of the frame, the dimmer adjusts by hand, and the fixture hangs from four ratchet straps. You pay more per watt than you do for a budget panel, but the diodes and the heat sink hold output across years of 12-hour flower cycles.
how to choose an led grow light for cannabis
Short answer: buy the HLG 350R for build quality and diode grade, the AC Infinity IONBOARD S24 for value, and the Spider Farmer SF-2000 for a 2x4 tent. Read the rest for the details that change the pick.
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Comparison at a Glance
- HLG 350R - best overall, about 330W, bar design, Samsung LM301H diodes, dimmable.
- AC Infinity IONBOARD S24 - best value, 240W, board design, Samsung LM301H diodes, controller ready.
- Spider Farmer SF-2000 - best for a 2x4 tent, 200W, Samsung LM301B diodes, dimmable driver.
- Mars Hydro FC-E3000 - best bar light on a budget, 300W, Mean Well driver, 3x3 flower coverage.
- ViparSpectra XS1500 Pro - best small tent pick, 150W, compact footprint, low price.
Before You Buy
Know three numbers first: your tent footprint, your target wattage per square foot, and your exhaust capacity. A flowering cannabis canopy needs roughly 30 to 40 watts of LED draw per square foot. A 3x3 tent is 9 square feet, so plan on 270 to 360 watts. A 4x4 is 16 square feet, so plan on 480 to 640 watts if you light the whole floor. Add a fan and a filter that move enough air to carry the heat out, because a bar light with a remote driver dumps less heat in the tent than a sealed panel does.
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HLG 350R: Best Overall
This is the light we hand to growers who run one tent and want it to last. The bar frame spreads photon density across the canopy, so colas at the edges finish close to the ones in the middle. Output is dimmable, which lets you run seedlings at low power and ramp up through stretch. The tradeoff is price. You will spend more here than on a 300-watt import, and you will replace it less often.
AC Infinity IONBOARD S24: Best Value
The S24 delivers 240 watts from a single board and pairs with AC Infinity's inline fans and controllers, so one app can run light, fan, and humidity. Diode grade matches the top pick. Coverage suits a 2x4 or a 3x3 for veg. If you already own AC Infinity gear, this is the pick that keeps your whole room on one schedule.
Spider Farmer SF-2000: Best for a 2x4
The SF-2000 draws 200 watts and fills a 2x4 footprint with even light for flowering. The driver is dimmable and detachable, which lets you move heat outside the tent. It costs less than the IONBOARD at the same coverage, and the tradeoff is a shorter warranty and a plainer build.
Mars Hydro FC-E3000: Best Budget Bar Light
At 300 watts with a Mean Well driver, the FC-E3000 covers a 3x3 for flower and a 4x4 for veg. Bars and a remote driver keep the canopy cool. It sits in the middle on diode quality, so expect slightly lower efficiency than the HLG at the same draw.
ViparSpectra XS1500 Pro: Best Small Tent Pick
For a 2x2 or a closet, 150 watts is the right size. The XS1500 Pro runs cool, dims down for seedlings, and costs little. Do not buy it for a 4x4. It will not carry a full flowering canopy at that width.
How to Pick the Right Light
- Measure your tent floor and multiply length by width to get square feet.
- Multiply square feet by 30 for a veg target and by 40 for a flower target.
- Compare that number against the true wall draw of each light, not the marketing wattage.
- Check the diode model and count against the price.
- Confirm the driver detaches if summer heat is a problem in your room.
- Pick the fixture whose footprint covers your canopy without gaps at the corners.
Setup Steps
- Hang the fixture with ratchet straps at the height the maker lists for the stage.
- Set the dimmer to 40 to 50 percent for seedlings and clones.
- Raise output in steps across veg as plants fill the space.
- Move to full power when flower sites set and the canopy is even.
- Check leaf temperature at the top colas and adjust height if leaves curl.
Verdict
Buy the HLG 350R if you want one light that covers a 3x3 for years. Buy the AC Infinity IONBOARD S24 if you want the same diode grade for less and already run AC Infinity fans. Buy the Spider Farmer SF-2000 for a 2x4, the Mars Hydro FC-E3000 for a cheap 3x3 bar light, and the ViparSpectra XS1500 Pro for a small tent. Match wattage to square footage and the rest sorts itself out.