Polystichum acrostichoides is more commonly known as the Christmas fern or Dagger fern.
It is often grown by gardeners to help prevent soil erosion in rocky or shallow garden borders, and is great to grow in a shady part of the garden.
They are also popular in Native American plant garden beds, as part of borders, inclines, or in parts of the garden with thin soils.
They belong to the Dryopteridaceae family (Leptosporangiate ferns) and are originally from eastern North America.
The scientific name is Greek in origin. Poly means many and stichos means in a row; this is in reference to their spores (how the fern reproduces) growing in rows.
This perennial evergreen fern has very few pests or diseases.
Gardener's HQ Guide to Growing Polystichum acrostichoides
Once planted, Polystichum acrostichoides are easily maintained. They are deer and rabbit tolerant. In addition, it maintains itself well during periods of drought.
This plant is also popular due to the spark of color it adds to a garden in winter and is thus a welcome addition to a winter interest garden.
Polystichum acrostichoides are best grown in dry to moist soil. If the soil is not well drained, then crown rot can set in.
Crown rot is caused from a fungus that lives in the soil. It affects plants if the soil is allowed to remain saturated in moisture. The fern may exhibit dry rot around the base.
If exposed to too much sun the fern may become stunted or pale. It is thus best planted somewhere with full or at least partial shade.
It grows best in organically rich soil, sandy or rocky soils, but will suffer in clay-based soil.
Start plants in the spring, after the last frost. Plant eighteen inches apart to reduce overcrowding.
Dagger fern is not a flowering or fruit producing plant as it reproduces by spores.
It requires minimal watering. Once a week usually gives it the moisture it requires, though in the summer it may require more regular watering.
Fertilize once a year. When planting, be sure to apply a layer of mulch or pine needles to retain moisture.
The fern grows in a cluster and is often used for an accent plant or for groundcover.
It will not form a continuous carpet.
They can also be grown indoors as a house plant. Indoor placement is best in front of a window, where the fern can bask in the sun in the morning, but can rest in the shade the rest of the day.
Quick Facts – Growing and Care Guide
Scientific Name: Polystichum acrostichoides
Common Name (s): Christmas fern, Christmas Dagger Fern
Growing Zone (USA / UK Hardiness): USDA Zones 3 to 9 / Europe/ H5 – hardy to about -15°C (5°F).
Native: Northern America. Natural locations include rocky slopes, especially besides streams in woodlands.
Best used for: Ornamental garden. Winter color. Slopes. Areas of erosion. Areas with shallow soils.
Tolerance: A very robust plant that can withstand deer and rabbits. It will also tolerate drought and rocky soils.
Life Cycle / Plant Type: Evergreen perennial. Rhizomes.
Plant Height: 12 to 30 inches (30 to 75 cm). Fountain-like clumped habit.
Plant Spread: 12 to 24 inches feet (30 to 60 cm). Fronds reach 12 to 32 inches (30 to 80 cm). Fronds lay close to the ground following the first frosts of autumn or winter.
Blooms: Ferns are non-flowering.
Leaf Foliage: Attractive. Dark green. Lanceolate. Leathery texture. Black spores are present beneath the leaves.
Growing Conditions and Location
Best Light Conditions: Shade. Partial shades. Dappled sunlight.
Suitable Soil Types: Moist. Rich organic soils give best results, but will tolerate poorer soils and sands.
Suitable Soil pH: As a woodland plant it prefers acidic soils.
Soil Moisture: Moist, Good drainage (especially in winter to help prevent rot). Grows well in dryer soils once established.
Sowing, planting, and Propagation: Further plants can be obtained by root division in the spring. Alternatively sow ripe spores in a moist soil or moss located in a shady area.
Care: No major problems but can be affected by crown rot. Little maintenance is required, simply tidy up in the spring. Water once per week.
Growing in pots and containers: Keep soil moist by regular watering. Excellent drainage is essential. Provide an all-purpose plant feed to help maintain soil nutrients in the pot.
Miscellaneous: The name Christmas Fern refers to the fact that the Fronds are evergreen and are thus some of the only green ground plants seen at Christmas time in the areas of Eastern North America where it is native.
Can be grown en masse to help prevent soil erosion.
Provides cover for smaller animals. Attracts nest-building birds looking for materials.
Although deer feed on this plant it seems to thrive on being ate and is heavily resistant to grazing.
Family: Dryopteridaceae (leptosporangiate ferns).
Closely Related Species: Polystichum polyblepharum (Japanese lace fern / tassel fern), Polystichum setiferum (Soft shield fern), Polystichum munitum (Western swordfern).
Frequently Asked Questions
What is Christmas Fern?
It is an evergreen fern that naturally grows in moist soils and riverbanks in woodlands. It makes a great ornamental plant to grow in shady parts of the garden for winter interest.
How tall are Polystichum acrostichoides ferns?
They typically reach about 2 feet (60 cm) in height, with a similar spread.
How do you Care for is Christmas Fern?
An easy plant to look after. Simply remove any damaged fronds at the beginning of spring.
When do Polystichum acrostichoides bloom?
As it is a fern, this plant will not produce blooms. Ferns typically pollinate by producing wind-borne spores.
Do Christmas ferns spread uncontrollably?
Although easy to establish, these plants are very unlikely to spread aggressively despite their spreading habit (which leads to a larger plant as opposed to spreading to other parts of the garden).