Thanks!
Yes it is one plant with 4 inflorescences. I got it as a 2 shot medium sized plant in 2013 (not absolutely sure about the date). Roots and leaves are growing like weed since.
Thanks, Rick. Yes, 12 h/d the lights are on. There is a little of daylight, but as it is about 2 m behind a south facing window that is nearly nothing.
Pics will come soon, when all flowers are open. Update: 10 are open at least 4 more are on the way...
BTW: To prevent one inflorescence growing into a light tube I put a little weight on it to bend it down. Soon it will bend a bit anyway. So I don't have to move it. Do you think that could do any harm?