A few years ago, the choice was simple: indoor grow? Go with a 600W HPS and that’s it. Today, LEDs have stormed into growrooms and flipped the table. Some say: “LED is the future — lower bills, cooler temps, more grams per watt.” Others stick to HPS because “it’s a proven technology that never fails.” Who’s right? Let’s calmly break down what a 600W HPS delivers compared to a modern 300–350W LED.
Electricity cost — the real difference
Let’s assume you’ve got a 120×120 cm tent and run one flowering cycle (8 weeks, 12/12).
- HPS 600W:
- consumption: ~600 W × 12 h × 56 days = ~403 kWh
- cost at €0.30/kWh = €120 just for the light
- LED 320W (e.g. quantum board):
- consumption: 320 W × 12 h × 56 days = ~215 kWh
- cost = €65
👉 The difference? On a single cycle you save around €55 on electricity. Do 3 cycles a year and that’s nearly €170.
Temperature — cooler or hotter?
- HPS 600W runs hot, like a furnace. A tent can quickly hit +28–30°C, requiring strong ventilation and sometimes even active cooling. In winter that’s a plus, since it heats the room. In summer it can be a nightmare if you don’t have AC.
- LED 320W produces far less heat. In practice, you’ll see a 3–5°C lower temperature in the tent. For anyone growing in an apartment without a good way to vent hot air, this can be a game-changer.
Yields — who gives more grams?
This is where it gets interesting.
- HPS 600W has long been the standard: with a solid grow you can hit 500–600 g per m². The spectrum is warm, great for flowering, though for veg you often need to supplement with CFL or MH.
- LED 320–350W of the new generation (Samsung LM301, Osram, full spectrum) realistically delivers 450–550 g per m². The buds are typically denser, with more trichomes and richer aromas.
👉 So per watt, LED often gives you more grams than HPS.
Who should pick LED?
- Growers with small tents, constantly fighting high temps.
- Those who watch every euro on their electricity bill.
- Anyone who wants “plug & play” — one light from seed to harvest.
- Quality seekers: LED often delivers tighter buds and more pronounced terpene profiles.
Who’s better off with HPS?
- Growers with lots of space and strong ventilation.
- Those who prefer tried-and-true setups over new tech.
- People growing in winter, where extra heat is welcome.
- Anyone who wants a cheap, reliable lamp to start with.
Initial investment
- HPS 600W with ballast and reflector: €100–150.
- LED 320–350W high-quality unit (HLG, Lumatek, Mars Hydro FC): €350–500.
LEDs cost more upfront, but they pay themselves off after 2–3 cycles thanks to lower bills and fewer climate issues.
Conclusion
- HPS 600W = cheaper upfront, powerful, reliable, but hotter and less efficient.
- LED 320–350W = higher initial price, energy-saving, cooler, often with better bud quality.
👉 If you’re just starting out and have a small tent, go with LED. If you’ve got a big attic and want to use the heat in winter — HPS still makes sense.
