The Cannabis Grow Light Buyer's Guide (LED vs HPS vs CFL)

5 min read

Four cannabis grow lights side by side — LED bar, HPS lamp, ceramic metal halide and a fluorescent T5 fixture

I once watched a fella build what he proudly called his “光 setup.” Three different light types in one tent. A 250W HPS in the middle, two CFL bars left over from the seedling stage he never took down, and a cheap LED panel he bought as a “supplement.” The tent looked like a disco. Hotspots bleaching the canopy under the HPS, dead corners where the CFLs did nothing, and a total draw of 500W doing a worse job than a single 300W LED would have. More lights doesn’t mean more light. It means more heat, more cables, and more things to go wrong.

So let’s do the honest comparison. No affiliate energy, no “1000W” fairy tales.

The short version:

  • LED — what most beginners should buy in 2026. Cooler, cheaper to run, full spectrum, lasts years
  • HPS — old reliable, grows heavy bud, but it’s a furnace and your bill knows it
  • CMH/LEC — the underrated middle child. Lovely spectrum, a bit more faff
  • CFL/T5 — seedlings and clones only. Not a flowering light in any real sense
  • Ignore the wattage on the box. The only number that matters first is wall draw — what it actually pulls from the socket

Want the full breakdown? Keep scrolling.

Are LED grow lights good for cannabis?

For most people starting out, yes — not because LEDs are magic, but because the maths works. Lower running cost than HPS, far less heat (which means less of an extraction headache), 50,000+ hours of life against about 10,000 for an HPS bulb, and a full spectrum that does both veg and flower from one fixture. A good LED bar at 200–320W actual wall draw covers an 80x80cm to 120x120cm tent and runs for years without a bulb change.

The catch is the market. It’s flooded with rubbish. That “1000W LED” on Amazon for sixty euro draws maybe 130W from the wall — the wattage is fiction and the money’s gone. When you compare LEDs, look at wall draw first, then efficiency (micromoles per joule — how much usable light per unit of electricity), then the PPFD map showing how evenly it covers the tent. A 200W LED from a reputable maker runs €140–250; a 320W for a bigger tent, €200–400. That’s the floor for a light that’ll actually flower a plant, not a luxury. DIG stock the honest brands and will tell you the real wall draw rather than the sticker.

Is HPS still worth it for growing cannabis?

It still grows dense, heavy buds — anyone who says HPS can’t compete on quality is wrong. That orange-red spectrum is exactly what flowering plants love. The problem is everything around it. A 600W HPS pulls 600W from the wall, the ballast adds another 60–70W, and roughly 60% of all that becomes heat. In a 1.2m tent that’s a furnace your extraction fan can’t win against. Running one 12 hours a day in flower costs around €75–90 a month in Ireland; the equivalent LED does the same job for about half. HPS isn’t wrong. It’s just not the smart first buy anymore. If someone hands you a free HPS kit, use it. If you’re spending money, spend it on LED.

What about CMH and CFL?

CMH/LEC (ceramic metal halide) is the quiet favourite. A 315W produces a beautiful full spectrum — the closest to sunlight of any grow light — with less heat per watt than HPS. Growers who use them tend to stick with them. The downside: dearer to buy, the bulb needs replacing every 12–18 months, and it needs its own ballast. For a second or third grow, worth a look. For a first tent, one more thing to think about.

CFL/T5 is for seedlings and clones, full stop. The intensity falls off so fast that anything past 10–15cm gets almost nothing — flower under CFLs and you get airy popcorn. A T5 running four 54W tubes draws 216W and makes maybe 150–200 PPFD up close; you need 600+ to flower properly. The numbers just don’t add up. Brilliant for keeping a mother alive or rooting cuttings. Not a flowering light.

So what should a beginner actually buy?

One full-spectrum white LED, sized to your tent, from a brand that publishes real wall draw and a PPFD map. That’s it. You don’t need separate veg and flower lights — that advice died when LEDs started covering the whole range from a single bar. Buy once, size it right, and put the money you saved on electricity into better genetics instead.

FAQ

What’s the best grow light for a beginner? A single full-spectrum LED matched to your tent size — roughly 200W for an 80x80cm, 320W for a 120x120cm. Cooler, cheaper to run, and it handles veg and flower without a bulb change.

How many watts do I need to grow cannabis? Think in real wall-draw watts, not box claims — very roughly 200–320W of genuine LED draw per small tent. The honest figure is the one measured at the socket, not printed on the lid.

Is LED or HPS better for cannabis? LED for most people: less heat, lower bills, longer life. HPS still grows excellent bud but runs hot and costs more to run. If you’re buying new, LED. If HPS is free, use it.

Can I flower cannabis under CFL lights? Not really. CFL and T5 are for seedlings and clones. The light is too weak past a few centimetres to make proper flower — you’ll get loose, airy buds.

Do I need a separate light for veg and flower? No. A modern full-spectrum white LED does both. The old metal-halide-for-veg, HPS-for-flower routine is no longer necessary.

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