Ornamental · Dryopteridaceae
Christmas Fern
Polystichum acrostichoides
Give it shade and soil that drains, and the Christmas fern will keep its green fronds standing all winter long.
Partial shade
Every 5–10 days
USDA 3–9
12–35 in · 30–90 cm
Overview
If you are new to ferns, this is a wonderfully forgiving one to start with, and it happens to be among the few that stay green right through winter. It settles into a neat, non-spreading clump of leathery, dark green fronds, and the little leaflets curl into shapes a bit like Christmas stockings, which is exactly how it earned its name. It belongs to the wood fern family and grows wild across much of the eastern woodlands, so it already knows how to look after itself.
What will reassure you most is just how tough it is. It shrugs off cold all the way down to -40°F (-40°C), takes deep shade in its stride, and even copes with the dry, rocky, root-filled ground beneath trees where most plants give up. Fresh fiddleheads unfurl in spring while last year's fronds are often still standing, so the bed never looks bare and you never feel like you have failed it.
Once it has settled in, it asks for almost nothing. Offer it shade, soil that drains, and a little patience while the clump fills out, and it will hold a quiet, evergreen presence for years to come. Many gardeners lean on it to steady a shady slope or carpet a woodland bed, and you can too, even on your first try.
Care
The short version: tuck it into part to full shade in rich, well-drained soil, keep it evenly moist while it finds its feet, and then you can mostly relax and let it be.
Light
At heart this is a shade lover. It thrives in partial to full shade and takes deep shade without complaint, which makes it a treasure for the gloomier corners where little else is happy. A bit of soft morning sun is welcome, but spare it the harsh afternoon glare, which scorches the fronds.
Water
While the fern is settling in, keep the soil evenly moist, reaching for the watering can every 5 to 10 days whenever the rain falls short. Once the roots take hold it handles short dry spells with ease, so you can relax your routine. The one thing it really won't stand is sitting in standing water.
Soil
Plant it in rich, well-drained loam with plenty of organic matter, though it will happily cope with sandy or shallow rocky ground too. It likes things a touch acidic, around a pH of 5.0 to 6.5. More than anything else, good drainage is what keeps it content, because wet feet invite crown rot.
Temperature
Few garden plants are as hardy as this one. It comes through anything from -40°F to 86°F (-40°C to 30°C), which covers USDA zones 3 through 9. Winter cold holds no fear for it, and the fronds keep their color straight through the frost.
Humidity
Ordinary outdoor humidity suits it just fine, so there is no number you need to chase. What truly matters to this fern is steady soil moisture, far more than any dampness in the air.
Feeding
This fern barely needs feeding at all. A light topdressing of compost or a balanced slow-release fertilizer in spring is plenty, and plenty of gardeners skip even that. Overfeeding only does it harm, so a light hand is the kindest hand.
Pruning
Pruning is just a once-a-year tidy. In late winter or early spring, before the new fiddleheads push up, snip away the old, tattered, or winter-damaged fronds so the fresh growth can come in clean and bright.
Size & spacing
Each clump reaches 12 to 35 inches (30 to 90 cm) tall with a matching spread. Leave about that much room between plants so the fronds have space to arch out, and the non-spreading clumps will keep their tidy shape without ever crowding their neighbors.
When to plant
There is no flowering season to keep up with on a fern, and no harvest either, which takes a lot of pressure off. Just set it out in spring as the soil warms and the fiddleheads begin to rise, then give it a season or two to settle comfortably in.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
This fern stays well with very little fuss, so problems are rare and almost always come down to soggy soil or a hungry pest. Get to know the two signs below and you will be able to catch either one early. Match what you are seeing, then step in gently before it spreads, and the plant will forgive the wobble.
Drooping fronds above a soft, darkened crown
If the fronds slump and the base turns soft and blackened, the culprit is crown rot, and it takes hold when the soil stays wet too long, often across a damp winter. Don't lose heart, because it is fixable. Water less, help the ground drain better, and gently scoop away any mushy, dark tissue at the base. Tucking the rhizome back in at a slight tilt lets water slide off the crown rather than sitting on it.
Fix:
- Improve drainage and reduce watering
- Plant the rhizome at an angle to shed water from the crown
- Remove and discard affected tissue
Nibbled leaflets and bare, stripped stems
Torn edges and stems picked clean usually mean the Florida fern caterpillar has been busy, and it does its eating after dark, so it can strip a frond before you ever spot it. The good news is that catching it is easy. Step out with a flashlight at night, look the plant over, and lift the caterpillars off by hand. Only a really bad outbreak calls for a suitable insecticide, since a watchful eye usually settles things on its own.
Fix:
- Hand-pick caterpillars
- Treat with an appropriate insecticide if infestation is heavy
Toxicity
Here is some lovely news if you share your home with pets or children: the Christmas fern is safe all around. The ASPCA lists it as non-toxic to cats, dogs, and horses, and there is no poison in the fronds to worry about for other animals or people either.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Rest easy, because the ASPCA puts this fern on its non-toxic list for cats, so a curious nibble is nothing to fret over. A cat that swallows a mouthful of fronds might feel a touch queasy, the way any plant can unsettle a stomach, but there is no poison at work here.
Dogs None
Your dog is perfectly safe around this fern, since it holds no toxins at all. A pup that chews a few fronds will be fine, though a really big helping of rough greenery might pass through a little messily, which is no cause for alarm.
Horses None
This fern is confirmed non-toxic to horses, so a grazing horse comes to no harm beside it. The fronds simply carry nothing that could poison them.
Rabbits Safe
A rabbit can browse these fronds happily and come away just fine. There is nothing in this fern that would trouble a bunny.
Livestock Safe
Cattle, goats, and sheep are welcome to graze near this fern without worry, because it carries nothing poisonous. It won't cause the kind of grief that some pasture ferns are known for.
Birds Safe
Pet and backyard birds are quite safe around this fern. Not a thing in the fronds will do them harm.
People Safe
There is no poisoning risk to people here, children included, even when little hands reach for the fronds. It isn't a plant grown for the table, so there is no reason to eat it, yet a curious touch or taste does no harm at all.
Varieties
Unlike a lot of garden plants, this fern comes almost entirely as the wild species, with named cultivars hard to track down. So there really is just the one to get to know, which keeps things simple.
Polystichum acrostichoides (species)
You will almost always meet it as the plain wild species, dressed in leathery, evergreen, dark green fronds whose little stocking-shaped leaflets keep their color through winter into the Christmas season, and named cultivars are a rare find.
How to propagate
Making more Christmas ferns is genuinely easy, whether you split a clump you already have or take the slower, gentler route of raising them from spores.
DivisionEasy
Spring · 1 to 2 growing seasons
The kindest, simplest way to grow your collection is to divide an established clump in spring, easing the crown apart and tucking the pieces back in, where they take a season or two to settle and fill out. If you fancy a slower project you can raise it from spores carried on the upper third of the fertile fronds, though that path asks for far more patience.
Myths
The Christmas fern is named for blooming or fruiting at Christmas.
It is an easy thing to assume, but ferns never flower or set berries, so the name has nothing to do with a winter bloom. It comes instead from the leathery fronds that stay green through winter into the Christmas season, paired with leaflets shaped like tiny Christmas stockings.