In favourable conditions the royal fern will grow into regal size. Among the native Finnish ferns, an old lady fern rootstock may grow 1.5 metre tall fronds but still not reach as high.
The sterile fronds of royal fern make a leguminous impression but it soon disappears on the discovery of the fronds with tassel-like clusters of spores, hence the English nickname Flowering Fern. The green sori turn brown by autumn. In deep shade there will be less of these fertile fronds. The royal fern spreads via rhizomes and spores.
The royal fern has become more rare in the wild as suitable habitats have been adopted to cultivation. As its range reaches southern Sweden, it could be expected to thrive also in Finland in the right locations, but it is rarely seen. If you wish to see a thriving royal fern, do check it out in the Rhododendron valley where it grows around the dividing ditch.