My set up is an unfinished basement, with concrete floor, with several floor drains for water run off. I have different lights in different areas. All lamps run on timers for an 18 hour day length.
For short plants, less than 10 inches tall above the rim of the pots. 48 inch T-12 or T-8 lamps, ordinary inexpensive cool white shop lights. Fixtures hung so leaves just about brush the lamps. Mostly seedling and cuttings of trees and seedling or low light requiring orchids.
48 inch, 4 lamp, T-5 with 6500K high output lamps. Hung a healthy 24 inches above the rims of the pots. For taller orchids, higher light requiring orchids, part shade sub tropicals. Lamps high enough leaves do not touch the lamps, need a couple inches to avoid burning. This is bright enough that a small bouganvillia will bloom in this space.
8 lamp, 48 inch fixture, T-5 with 6500K high output lamps - This replaces a 430 watt HP Sodium fixture, it is quite bright. Hung a full 3 feet over the pots. Some pots on floor, 5 ft, get enough light to do well. I bloom Vanda and Cymbidium orchids, almost too bright for Cattleya. This is where high light trees spend the winter. And tall trees.
430 Watt High Pressure Sodium Lamps - color rendition of the light is awful to the human eye, plants seem fine. These are Sun Agro lamps that have been doped for extra blue output for agriculture, these are not the yard or street lights, though to the eye the color seems the same. These are work horses, and not very efficient with electricity. However, I have been using these lamps for over 25 years and the ballasts never fail to light. Rugged and tolerant of humidity.
1000 Watt High Pressure Sodium. - this lamp is really hot, but for my tallest orchids, and high light requiring orchids, it can't be beat. Ballast is over 20 years old, just keeps on firing, so as long as it fires I'll keep replacing the bulb every 3 years or so. Throws a lot of heat, you MUST have fans to keep air moving and distribute the heat away from the plants.
Lamp replacements - 40 Cool whites, - tend to run 2 + years
T-5 - these surprised me, lamps do burn out in about 12 to 18 months.
HSP - 430 and 1000 Watts, these I run for about 3 years, they rarely actually burn out, but output drops with time.
Metal Halide - Similar heat and energy consumption to the HPS, but they burn out in less than 18 months, and were costly enough to replace I quickly switched to HPS.
LED - I have not ventured into LED recently, 8 years ago the products available did not produce enough lumens, plants grew weak, product quality was low, had to replace a fixture 3 times before I got one to light on day 1. Have not returned to this. I know technology has improved, for those new to under light growing, start with LED. It should work.
If you plan on more than 200 plants under lights, it is best if you construct a vapor barrier to keep the humidity the plants generate from migrating through the house. Have an exhaust fan to vent humid air outdoors, keep a negative pressure in the growing space. Humidity will migrate and over time damage window sashes, and peel wallpaper off walls 2 floors up. It is worth the effort.
Hope that helps. Photo is from 2008, it has changed a bit, the T 5's replaced some of the others. Mostly orchids, some trees, no marijuana.
. I really like my HO fixture, I only got it last December but so far it's great. Before I was using 4' t12s and a 250w hps. The guy at the local hydro store is trying to get me to try a LEC but they're about double the cost of what a MH would be. I have to decide soon about finding something stronger because my plants are getting big and I need something that will penetrate through the canopy.
