I bought these three ferns at the same time. They came in 10cm pots so I planted them in 20-30cm pots. They are in a shady location with a limited amount of sunlight for some of the day.
I water them once a week just a little bit as the soil seems to stay damp for a while. I make sure the soil isn't waterlogged.
They grew a little when first planted, but since then they haven't grown at all, and the new growth seems to die or be generally unhealthy.