Halfway grown bulbs in wintertime often do not grow into strong ones that will flower. So give them as much light as possible, Tschimm.
There is no winter under T5s 😉
Actually the plant is getting more light now as it got in August, when it was raining nearly every day here in Zurich.
The new growth of summer got too wet in our bad summer and rotted.
But now it made two instead of the one I've lost 😄