I grew it from seed years ago. You could use any lightbulb you have, I think most would work for germination. I went with a florescent light fixture because I already had it and I could fit two trays under the light easily. I used modular metal shelfs from Target.
I used old plant cell trays indoors on a table and setup the light above it on a timer. I think it was 16hrs on and 8hrs off. Anytime between 12-18hrs on
should work. Just sprinkle seeds on top of soil and keep moist. I used a spray bottle of
water for germination. I believe it took a month to germinate.
Also make sure after the initial soaking of soil at planting time you allow soil to dry out a bit between mistings. That will prevent mold and allow seeds to breath. You want the top layer to look lighter in color to tell you it's dried
enough between watering (mistings)
Then transplant into larger container and harden outside when weather permits. I keep mine in a container and use it pretty heavily to prevent invasion of the stinging
nettle. Especially by seed, you could clip seeds off and save. Also trimming the plant and combining with worm castings makes a great liquid fertilizer that adds beneficial bacteria to your soil while it
boost your plants immune systems.
You could also use sunlight if available. I grew my stinging nettle in March so the above option was my best bet.
Good luck