LED vs HPS Grow Lights for Cannabis: Which Is Better?

The short answer

Buy LED unless you have a specific reason not to. A current 480W bar-style fixture outgrows a 600W HPS in a 4x4 tent, runs cooler, and draws less power at the wall. I say that as someone who ran magnetic-ballast HPS for years and only switched after watching a watt meter.

Cannabis Grow Lights for the Flowering Stage: PPFD, Spectrum and Schedule

HPS still makes sense in two cases: you already own the hood, ballast, and bulbs, or your grow space sits in an unheated garage where the lamp doubles as a heater.

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What actually differs

• Efficiency: Good horticultural LEDs hit 2.5 to 3.2 µmol per joule. Single-ended HPS lands near 1.3 to 1.6. Double-ended HPS gets closer to 1.9 but still trails.
• Heat: HPS dumps roughly 70 percent of its input as heat you have to exhaust. LED puts more of it into photons and less into the room, though drivers and boards still warm a tent.
• Spectrum: HPS is a fixed blob of yellow-orange light. LEDs let you add deep red for flower, blue for stretch control, and dim channels independently.
• Lifespan: HPS bulbs lose output around 10,000 hours and want replacing every 2 to 3 grows. LED diodes are rated near 50,000 hours with maybe 10 percent loss.
• Startup cost: This is HPS's only real edge. A 600W kit can cost less than half of a comparable LED, before you add the extra fan and AC load.
• Coverage: Bar LEDs spread light edge to edge. Single-ended HPS in a wing reflector throws a hot center and weak corners.

Pick this first

If you grow in a tent between 2x4 and 4x4, buy a 240W to 480W LED with a bar or quantum-board design, a dimmer, and a rating you can verify with a PAR meter. Match wattage to footprint, not to the number on an old HPS box. A 480W LED replaces a 600W HPS at the canopy, and a 240W unit covers a 2x4 for veg and light flower.

cannabis grow lights for beginners budget

Options by grower

Best all-around: 480W bar LED

This is the default for a 4x4. Even spread, dimmable to 25 percent for seedlings, and no bulb swaps. Add a small heater in winter if your lung room drops below 68F.

Best on a budget: 240W board LED

Plenty for a 2x4 or a 3x3 veg tent. Cheaper boards often overstate output, so check the driver wattage rather than the marketing name.

Best if you already run HPS: keep it

Swap in a fresh bulb, clean the reflector, and fix your airflow before spending on new lights. A tired bulb is the single biggest yield killer in HPS rooms.

Best for cold rooms and large commercial bays

Double-ended HPS or high-output LED with supplemental heating both work. At scale, the power bill usually decides it, and that math favors LED in most US markets.

Numbers that matter more than lamp type

Light type is secondary to how much light reaches the canopy. Aim for 400 to 600 PPFD in veg and 700 to 1,000 PPFD in flower without CO2. That puts daily light integral near 30 to 45 mol/m2/day in veg and 40 to 60 in flower. A cheap HPS hitting those numbers beats an expensive LED that doesn't. Buy or borrow a PAR meter once, and you stop guessing.

Also watch leaf temperature. HPS raises it a few degrees, which helps in a chilly room and hurts in a sealed one. LED runs closer to air temp, so you may need to push your room warmer by 2 to 4 degrees to keep metabolism up.

Bottom line

New grow, normal room, normal budget: go LED. Existing HPS setup that still works: fix the bulb and airflow first, then plan the switch when the ballast dies. Either way, spend on airflow and a meter before you spend on a bigger fixture.