I saw your question on the mosses and ferns forum. I googled flowering fern and it is probably incarvillea, which I have never seen called a flowering fern before in 60 years of gardening. But here's a link, and if you google incarvillea you will get all kinds of planting instructions.

It has always in the past been known as hardy gloxinia. Ha. Marketing.

Sandy

Here is a link that might be useful: Flowering fern

Just as a technical note: by definition, ferns do not have flowers. Ferns have been around far longer than flowering plants, and they make spores without any flower. The spores often form on the undersides of their fronds, sometimes on a separate fruiting body.

She probably talking about these flower ferns or known as Hardy Gloxinia..