Hi Erwin,.
am although no professional, but I still write ' times what...
3 cm long roots listens to actually then, that she would like to grow lot.
If she then also does so and begins to rot, is sure of than from boundary conditions, especially temperature.
I made my 3 cm titanum bulb which so beautifully warm, auif of an aquarium cover in dry to moderately moist substrate, because of the beautiful weather in the winter garden, as she had some 2-3 cm long roots and eine2 cm long bud.
Now it has but cooled down since the last weekend and when I saw this afternoon after the Corm, 3 of the formerly completely healthy root had died.
I suspect that it was due to the "Bodeheizung lack in the winter garden". I would leave it better on the Aquarium cover.
This observation only as a suggestion....
Join in for a professional opinion Erwins desire...;-)
MfG,
Bernhard.