This small-scale hardy fern is very adaptable in the Pacific Northwest and makes a great year-round groundcover.  Blechnum penna-marina, is happy in light shade but will grow in deeper shade as well as full sun if the soil is kept moist.

Blechnum penna-marina

The new foliage emerges bronzy-red, aging to deep green.  The tightly packed fronds slowly spread by creeping rhizomes to form a very effective groundcover.  Its variety B. ‘Cristatum’ is similar and its tips are curiously crested.  In both forms the fertile fronds are reddish brown, thin and upright.

FAMILY NAME:  Blechnaceae

COMMON NAME:  Hardfern, alpine water fern

ORIGIN:  New Zealand, South America

PREFERRED GROWING CONDITIONS:  Moist, shady woodland spot in well-drained, acidic, humus-rich soil. Shade to part shade is perfect but will take full sun in the Pacific NW if kept moist.

MANAGEMENT:  Groom in late winter or early spring.  Remove old fronds as necessary.  Cut well established plants to ground in late winter to fully appreciate the new foliage; recommended only on older clumps that have become ratty or are badly damaged by winter wet or snow cover.

PROPAGATION:  Division in spring; sow spores in late summer


COMPANIONS & USES:  Heuchera, ajuga, dwarf polygonatum.  Amongst rocks, in rockeries, niches, and walls.

IDEAL SPACING AT PLANTING TIME FOR FULL COVERAGE IN 2-3 YEARS:  8” on center or less.  It can be a bit slow to spread in the beginning.


B. penna-marina, Little Hard Fern, is an evergreen fern with a Royal Horticulture Society Award of Merit. It’s height and spread in one year are 4” x 5” and in five years will reach 4-6” x 24”+. The foliage is dark green, small, leathery and glossy.  Zone 5-8.

B. penna-marina ‘Cristatum’ is a bit smaller than the species.

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