LED is the only thing i know. I would love to run hps in the winter for added heat. I know lots of growers who went back to them because they say theyre much better for flowering. I wouldnt know tho
long as you have an enclosed hood, and use 600w bulbs, its pretty easy to manage in a tent unless you're doing DWC or something that requires cold root systems.
A couple decades down the line, the plants will have been unintentionally selected to prefer preforming under LED's, will just take time and a lot of growing/breeding to get there. People aren't specifically breeding for this parameter, it's happening natural selection style, but in a synthetic way lol.
Right now though, yea, you still have to buy a nearly $1000 LED grow light (seen some promising ones in the roughly 500 range in last couple years though, havent made the plunge, might this summer though) to truly match the performance potential of a single $160 1kw HPS digital ballast setup from ebay, $10 generic chinese bulb included in that statement.
With certain sativa genetics, ive pulled right at 2lbs from a single plant under a 600w HPS with little training or significant effort or focus on the plant (DWC). I neared 3lbs on 2 occasions in 6x5 under 1kw hps with 2 largely untrained plants. Good luck doing that under a 600w LED without a lot of training, planning, and conscious effort. It happened to me entirely by accident with an HPS sometimes though, and while being a fairly lazy cheap-skate grower
If you dont mind slightly lanky plants, you can reliably pull close to 3 lbs from 7x8 under a single 1kw HPS from the right sativas genetics in a grow room designed specifically for the task/purpose + a solid grower. (not really a tent, more like opaque white vinyl or mylar + some carpentry skills)
That growing niche has largely been driven extinct by today's cannabis climate/culture though. Was fun while it lasted though for sure lmao. All that was really only worth the effort when you could call 300 a zip for the headies lmfao.
