Hello Eva,
here a picture of the bipinnatifida in the 'Ikea -box' ; the box is closed, I made some ventilation holes in the top.
Next to the bipinnatifida you can see B. lyalli lyalli f.masoalaensis. This was a difficult plant in the beginning (lost most of the leaves), since I placed it in this box, it is growing very well.
Next a picture of the 7 Begonia that I recieved from you, including the Columnea. All are doing well !
For more difficult species it is recommended to use some 'Blahton' first in the box, and put the plants on top. By doing so, the roots are not always in the water, but are allowed to dry. When the boxes are closed, you only have to water them every 2-4 weeks. Take care for new additions, for some species (like B. bogneri) this seems to be to wet, they can start to 'mould' and rot ...
Regards,
Stijn