Ornamental · Aspleniaceae
Hart's Tongue Fern
Asplenium scolopendrium
Give it deep shade, steady moisture, and a touch of lime, and this glossy strap-leaved fern holds its color right through winter.
Full shade
Every 5–10 days
USDA 5–9
12–18 in · 30–46 cm
Overview
The hart's tongue fern stands apart from almost every other fern by what it doesn't do. Its fronds never split into the lacy, feathery shape most people picture. Instead they unfurl as long, glossy, undivided straps of bright green, growing from a tight central crown into a tidy shuttlecock of foliage.
It belongs to the spleenwort family and grows wild across Europe, where it clings to shaded limestone walls, rocky banks, and the mouths of caves. That habit tells you what it wants at home: cool shade, a sweet alkaline soil, and steady moisture without ever sitting in water. In the right corner it is evergreen, holding its fronds straight through a hard winter.
This is a slow, patient plant rather than a quick filler. It asks for shelter and shade, and it gives back a structural, almost reptilian texture that lights up a dark spot under trees or beside a north wall.
Care
The short version: full to partial shade, soil kept evenly moist but sharply drained, and a sweet alkaline mix with a little lime suit it best, alongside the higher humidity it grew up with on shaded rock.
Light
This is a shade plant through and through. It wants full to partial shade, the kind of dappled or deep cover it gets under trees or against a north wall. Direct sun scorches the fronds, so keep it out of hot afternoon light.
Water
Keep the soil evenly moist but never waterlogged, watering every 5 to 10 days and more often through a dry spell or the first season after planting. The catch is drainage: it hates standing water as much as it hates drought, so moist soil that drains sharply is the sweet spot.
Soil
Plant it in humus-rich, well-drained soil that leans alkaline, ideally a pH between 6.5 and 8.0. It is one of the few ferns that genuinely thrives on lime, so a chalky or limestone-rich mix suits it where most plants would sulk.
Temperature
It is properly cold-hardy, taking winter lows down to -20°F (-29°C) and summer warmth up to about 75°F (24°C). Those extremes are why it stays evergreen across zones 5 to 9 rather than retreating underground.
Humidity
Coming from shaded rock and cave mouths, it likes the air on the damp side, around 50% to 80%. In a dry house or an exposed bed the frond tips brown, so group it with other plants or set it where the air stays still and moist.
Feeding
Ferns are light feeders, so go easy. A diluted, balanced liquid fertilizer once in spring is plenty, and overfeeding does more harm than good.
Pruning
There is little to do here. Pull off dead or damaged fronds whenever you spot them, and cut back the tatty, winter-burned old fronds in late winter, just before the new croziers start to unfurl.
Repotting
A potted plant only needs moving every 2 to 3 years, or sooner if roots push through the drainage holes, the crown looks congested, or water runs straight through. Step it up into a slightly larger pot with fresh, lime-rich, gritty mix.
Size & spacing
It is a compact, slow grower, reaching about 12 to 18 inches (30 to 46 cm) tall and roughly the same across. Give each plant 12 to 18 inches (30 to 46 cm) of room so the crowns can form their full rosette of fronds.
When to plant
This fern is hardy and in no hurry. Sow ripe spores indoors in spring if you want to raise your own, and set young plants out in spring once hard frost has passed. It is evergreen in zones 5 through 9, so once established it carries its fronds year-round rather than dying back to the ground.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Sow ripe spores indoors in spring at about 15°C (60°F)
- Plant: Spring, after the danger of hard frost has passed
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Most trouble with this fern traces back to water and light rather than pests. Wet feet and too much sun cause nearly all of it. Match what you see below, then adjust the conditions before the damage spreads.
Fronds collapsing while the roots turn black and mushy
This is root rot, and it comes from soil that stays too wet rather than from any disease you catch. Lift the plant and you'll find soft, foul-smelling roots instead of firm pale ones. Cut away the rot, fix the drainage, and repot into a gritty, lime-rich mix before the crown drowns.
Fix:
- Improve drainage immediately
- Reduce watering frequency
- Repot into a gritty, well-drained, lime-rich mix and trim away rotted roots
Scorched brown tips and edges on the fronds
Crispy edges mean sun scorch, usually paired with dry air or soil that ran short of water. The damage shows worst on the side facing the sun while shaded fronds stay green. Move the plant somewhere shadier, raise the humidity around it, and keep the soil evenly moist.
Fix:
- Move to a shadier spot
- Raise humidity around the plant
- Keep soil evenly moist
Old fronds browning and tattering through winter
This is winter burn on the oldest outer fronds, the work of cold and drying wind on an evergreen plant. It looks rough, but the central crown is fine and pushes fresh growth in spring. Trim the tatty fronds back in late winter, before the new croziers start to unfurl.
Fix:
- Cut back damaged fronds in late winter before new croziers unfurl
Toxicity
Good news for a shade garden with pets and children: this fern is safe. As a true fern it carries no known toxin, so cats, dogs, and grazing animals can be around it without risk. The only real caution is mechanical, since the fronds and spores can scratch or irritate sensitive skin, so wash your hands after handling it.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cats can be around this fern without any toxic risk. A curious nibble might cause a little stomach upset, the same as any plant matter, but nothing more.
Dogs None
There's no poison here for dogs. A dog that chews a frond may drool or be briefly off its food from the roughage, yet the plant itself does it no harm.
Horses None
Horses can graze near it safely. True ferns of this kind carry no toxin that would trouble them.
Rabbits None
A rabbit can nibble the fronds without coming to harm. Keep it as one part of a varied diet rather than the whole meal.
Livestock None
Cattle, goats, and sheep face no poisoning from this fern and can share its company in a shaded paddock.
Birds None
Birds are in no danger around the plant, whether they perch in it or pick at a frond.
People None
The fern is safe to handle and grow around children. The only thing to note is that the fronds and spores can scratch or irritate sensitive skin, so wash your hands after a good prune.
Fronds and spores may cause mild mechanical irritation in sensitive individuals; wash hands after handling.
Varieties
Beyond the plain species, growers prize a handful of selections for the way their fronds twist, ripple, and flare. These are the forms worth knowing.
'Crispum'
A popular ornamental form with strap-like fronds whose margins are strongly frilled and crisped into tight waves.
'Undulatum'
Its fronds ripple with pronounced wavy edges running the full length of each blade.
'Angustatum'
This one carries narrower, more strap-like fronds than the plain species.
'Sagittatum'
Each frond flares into a distinct arrow- or fishtail-shaped lobed base.
var. americanum (American hart's-tongue fern)
A rare North American native of limestone sinkholes, federally protected and not the form you'll find sold in garden centers.
How to propagate
You can multiply this fern two ways: split an established clump for quick results, or grow it the slow way from spores.
DivisionModerate
Late winter to early spring · 2-3 months for divisions; spore-grown plants take 1-2+ years to reach garden size
The simplest route is division in late winter to early spring. Lift a mature clump that has formed several crowns, split it apart, and the pieces settle in over two to three months. You can also raise it from spores sown on the surface of a sterile mix as soon as they ripen, kept at about 60°F (15°C), but that path is slow and a spore-grown plant needs one to two years or more to reach garden size.
Myths
Because its fronds are undivided and strap-like, it is not a real fern.
It is every bit a true fern. It reproduces by spores, carried in neat herringbone rows of sori along the undersides of the fronds, even though the leaves never split into the lacy shape most people picture.
Hart's tongue fern is endangered and illegal to grow.
The widespread European species is common and freely sold for the garden. Only the North American native variety, var. americanum, is rare and legally protected, and that is not the plant on the nursery bench.