Family: Blechnaceae
Common Name: Hard Fern, Water Fern

Widely distributed in temperate to tropical climates throughout the world, this genus consists of some 200 terrestrial and epiphytic ferns which grow from rhizomes. The largest number occurs in the southern hemisphere, and these are invariably tender in the northern hemisphere, in which case they are grown under glass. However, in the UK a few hardy blechnums are commonly grown, especially in woodland gardens. The majority occur in damp or swampy places. Some species have firm, thick, dark green fronds, while others have softer fronds which are lighter in colour. The rhizomes are covered with glossy brown scales and range from short-creeping to long-creeping.

Species

B. camfieldii grows naturally near saltwater inlets and creeks or in swampy, low-lying areas of Australia's northern New South Wales and southern Queensland. With age, it grows a small trunk about 1 m (3 ft) tall and the upright fronds turn dark green. The young fronds are bronze-pink.

B. cartilagineum, gristle fern, comes from the drier areas of the eastern states of Australia and northern Tasmania. It has a short-creeping rhizome, covered in black scales, and the fronds are erect or semi-erect, changing in colour from pink to pale green as they mature.

B. chambersii, lance water fern, is found growing in well-shaded, moist areas of southern Australia and New Zealand. It has drooping, dark green fronds, up to 60 cm (24 in) long.

B. minus, soft water fern, has pinkish fronds when young and glossy, erect, bright green fronds as it matures. It also forms a trunk with age. Its natural habitat is wet gullies in much of Australia and New Zealand. It is able to tolerate full sun, provided it receives adequate moisture and it will increase easily from offsets.

B. nudum, fishbone water fern, grows naturally in cool, moist, protected areas of the eastern states of Australia, Tasmania and South Australia, where it often forms dense colonies. The upright fronds form a spreading rosette.

B. patersonii, strap water fern, has an erect rhizome and dark green fronds, soft pink when young. They grow up to 40 cm (16 in) long and can vary in shape, from undivided to segmented. Strap water fern requires good soil and a well-protected, damp, shady position if it is to thrive.

B. penna-marina, zone 8, is a very small species found in Australasia and southern South America. It is also common in gardens in the US. Its narrow, wiry, branching rhizome is long-creeping and short, dark green fronds grow only to 20 cm (8 in) long.

B. wattsii, hard water fern, is a vigorous grower. In its native range, which is moist mountainous areas of all Australian states except Western Australia, it spreads by underground stolons to form tangled groundcover. It can be grown easily in a large pot or in a protected spot in the garden.

Cultivation

These ferns require ample moisture, as well as shade and protection from wind. The soil should be the normal peaty mix suitable for ferns. There should be ample organic matter for moisture retention, but the soil should also drain freely. Feed monthly during the warmer months with quarter-strength soluble fertilizer. They can be grown in the garden or greenhouse according to species, although some are more easily cultivated than others.

Climate

The species below are suited to zone 9 and above unless otherwise indicated.