Ornamental · Aspleniaceae
Hart's Tongue Fern
Asplenium scolopendrium
Give it deep shade, steady moisture, and a bit of lime, and this glossy strap-leaved fern keeps its color going right through winter.
Full shade
Every 5–10 days
USDA 5–9
12–18 in · 30–46 cm
Overview
Here's the fun thing about the hart's tongue fern: it barely looks like a fern at all. The fronds never split into that lacy, feathery shape you'd expect. Instead they roll open as long, glossy, undivided straps of bright green, rising from a tight central crown into a tidy little shuttlecock of leaves.
It's part of the spleenwort family, and out in the wild across Europe you'll find it clinging to shaded limestone walls, rocky banks, and cave mouths. So what does it want at home? Pretty much that same setup: cool shade, a sweet alkaline soil, and steady moisture, just never sitting in water. Pop it in the right corner and it stays evergreen, holding onto its fronds even through a hard winter.
Don't expect it to fill a space in a hurry, though, because it's a slow, patient grower. Give it shelter and shade, and in return you get a bold, almost reptilian texture that brightens up a dark spot under trees or beside a north wall.
Care
The short version: it's happiest in full to partial shade, in soil kept evenly moist but sharply drained, in a sweet alkaline mix with a bit of lime, plus the higher humidity it grew up with on shaded rock.
Light
This one's a shade lover, plain and simple. It wants full to partial shade, that dappled or deep cover it'd get under trees or against a north wall. Keep it out of the hot afternoon sun, though, or the fronds will scorch.
Water
Keep the soil evenly moist but never waterlogged, watering every 5 to 10 days, and a bit more often during a dry spell or that first season after planting. Here's the catch: drainage matters just as much, because it hates sitting in water as much as it hates drying out, so moist soil that drains sharply is the sweet spot.
Soil
Give it humus-rich, well-drained soil that leans alkaline, ideally a pH between 6.5 and 8.0. It's one of the rare ferns that genuinely loves lime, so a chalky or limestone-rich mix suits it just fine where a lot of plants would sulk.
Temperature
It's seriously cold-hardy, taking winter lows down to -20°F (-29°C) and summer warmth up to about 75°F (24°C). That's exactly why it stays evergreen across zones 5 to 9 instead of disappearing underground.
Humidity
Since it grew up on 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 tips will brown, so group it with other plants or set it where the air stays still and moist.
Feeding
Ferns are light feeders, so there's no need to go overboard. A diluted, balanced liquid fertilizer once in spring is plenty, and overdoing it actually causes more harm than good.
Pruning
There's honestly not much to do here. Pull off any dead or damaged fronds when you spot them, and cut back the tatty, winter-burned old fronds in late winter, right before the new croziers start to unfurl.
Repotting
A potted one only needs moving every 2 to 3 years, or sooner if the roots poke through the drainage holes, the crown looks crowded, or water runs straight through. Bump it up into a slightly bigger pot with fresh, lime-rich, gritty mix.
Size & spacing
It stays compact and grows slowly, topping out around 12 to 18 inches (30 to 46 cm) tall and about the same across. Give each one 12 to 18 inches (30 to 46 cm) of space so the crowns can spread into their full rosette of fronds.
When to plant
This fern's hardy and in no rush at all. Want to raise your own? Sow ripe spores indoors in spring, then set young plants out in spring once hard frost has passed. It's evergreen in zones 5 through 9, so once it's settled it hangs onto its fronds all year 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 of the trouble you'll run into with this fern comes down to water and light, not pests. Soggy roots and too much sun are behind nearly all of it. Find the symptom that matches below, then tweak the conditions before things get worse.
Fronds keeling over while the roots turn dark and mushy
What you're looking at is root rot, and it comes from soggy soil, not some bug going around. Pop the plant out of the ground and you'll feel it: the bad roots are soft and smell off, while good ones stay firm and pale. Snip away the rot, sort the drainage out, and get it into a gritty, lime-rich mix, and the crown should bounce back.
Fix:
- Improve drainage immediately
- Reduce watering frequency
- Repot into a gritty, well-drained, lime-rich mix and trim away rotted roots
Crispy brown tips and edges on the fronds
Crispy edges? That's sun scorch, and it usually shows up when the air's too dry or the soil ran low on water. Notice how it's worst on the side facing the sun, while the shaded fronds are still nice and green. Just move it somewhere shadier, get some more humidity around it, and keep the soil evenly moist.
Fix:
- Move to a shadier spot
- Raise humidity around the plant
- Keep soil evenly moist
Older fronds going brown and ragged over winter
Don't panic, this is just winter burn on the oldest outer fronds, and it's what cold and drying wind do to an evergreen. It looks a bit rough, sure, but the middle of the plant is fine and it'll push out fresh growth once spring rolls around. Trim the ragged fronds off in late winter, right before those new croziers start to unfurl.
Fix:
- Cut back damaged fronds in late winter before new croziers unfurl
Toxicity
Good news if you've got pets or kids sharing the shade: this fern is safe. Being a true fern, it doesn't carry any known toxin, so cats, dogs, and grazing animals can all hang around it without any risk. The only real thing to watch is physical, because the fronds and spores can scratch or irritate sensitive skin, so just wash your hands after handling it.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Got a cat? No worries here, since this fern isn't toxic to them. A curious nibble might upset their stomach a touch, the way any plant would, but that's about it.
Dogs None
There's nothing poisonous here for a dog either. If one chews a frond it might drool a bit or go off its food for a moment from the roughage, but the plant won't do it any harm.
Horses None
Horses are totally fine grazing nearby. A true fern like this just doesn't carry anything that would bother them.
Rabbits None
A rabbit can nibble the fronds and be perfectly okay. Just keep it as one part of a mixed diet, not the whole spread.
Livestock None
Cattle, goats, and sheep? All fine around it, since this fern won't poison any of them, and they can happily share a shaded paddock.
Birds None
Birds are safe with it too, whether they're perched among the fronds or having a peck at one.
People None
It's safe to handle and to have around kids. The only thing worth remembering is that the fronds and spores can scratch or irritate sensitive skin, so give your hands a wash after a prune.
Fronds and spores may cause mild mechanical irritation in sensitive individuals; wash hands after handling.
Varieties
Past the plain species, gardeners really like a handful of selections for the way their fronds twist, ripple, and flare. Here are the forms worth knowing about.
'Crispum'
It's a favorite garden pick, with strap-shaped fronds whose edges are heavily frilled and crimped into tight little waves.
'Undulatum'
You can spot it by the bold wavy edges that ripple all the way down each blade.
'Angustatum'
It's the one with slimmer, more strap-like fronds than you'd see on the plain species.
'Sagittatum'
Take a look at the base of each frond and you'll find a neat arrow- or fishtail-shaped set of lobes.
var. americanum (American hart's-tongue fern)
It's a rare North American native from limestone sinkholes that's federally protected, so it's not the one you'll actually find for sale.
How to propagate
There are two ways to make more of this fern: split an established clump for quick results, or take the slow road 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 easy route is division in late winter to early spring. Grab a mature clump that's grown a few crowns, pull it apart, and the pieces settle in over two to three months. Fancy a project? You can also sow ripe spores on the surface of a sterile mix as soon as they ripen, kept at about 60°F (15°C), but it's a slow game, since 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 really is a proper fern, no question. It reproduces by spores, lined up in neat herringbone rows underneath the fronds, even though the leaves never split into that lacy shape most folks picture.
Hart's tongue fern is endangered and illegal to grow.
The common European species is everywhere and sold openly for gardens, so you're good. Only the North American native variety, var. americanum, is rare and legally protected, and that's not the plant sitting on the nursery bench.