How to Fertilize Japanese lace fern?
Very dilute fern feed monthly during warm active frond growth

Japanese lace fern · Polystichum polyblepharum
Also known as: tassel fern
Grow in fertile, humus-rich, well-drained soil in deep or partial shade; protect crowns from excessive winter wet and provide a mulch around the crown to prevent crown from drying out
Very dilute fern feed monthly during warm active frond growth