Problems with Enderlily seeds in Minecraft?

I have some mods in 1.7.10, as well as extra utilities and their Enderliliensamen.

I've put these on Endstone in darkness with a chunkloader, but they do not grow above 14%. They reach the first stage very fast, but nothing happens after that. I have been continuously opening the inventory screen (not the Escape menu) for 3 days, but they are not growing any further.

Am I doing something wrong?

Why in the dark? They need light, like almost everything you can grow.