I have a 40W red and blue growlight with 4 goosneck arms, and each have 20 LED’s. This may be a stupid question but is there a range/distance that you should keep the growlights from the seedlings?
Also, are roses fine with any brightness from the LED’s?
I keep 100w LEDs about 20" above my seedling trays 24 / 7 during indoor germination season. They will tell you they need more light by stretching if that is the case. If the room is cool I suspect they could easily take even more light than that.
I would get a 40w as close as is safe.
Proper lighting is very hard to judge without a meter. Distance especially, because (just as an example), if your lighting is “perfect” at 6 inches, at 12” the light intensity drops to only 25%, at 24” 6.25%, etc.
I use the Photone app, and target an average Daily Light Integral of 20 to 25, at the “average” canopy level. I also use a maximum photoperiod of 18 hours, because my experience is fewer blooms with 24 hour lighting.
Roses like a lot of light. Purdue has a decent summary of DLI to acquaint yourself.
I also use Photone. They sell a little diffuser for ten bucks that you can put on your phone camera.