Southern shield fern
Thelypteris kunthii · Aspleniaceae
Large, soft, light green, arching fronds. It is the easiest fern for the Deep South: it tolerates heat, drought and more sun than most.
- Size
- 3 ft tall, 3 ft wide
- Zones
- 7 to 10
- Light
- Part sun to shade
- Flowers
- Grown for its leaves
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around southern shield fern
The planner designed this bed around southern shield fern when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 7, part shade. It chose the other plants from the 535 that suit those conditions, and says below why southern shield fern stands where it does.
The plants
- 1 Southern shield fern × 1, green leaves
- 2 Leadwort × 11, blue
- 3 Moor grass 'Greenlee' × 4, tan
- 4 Japanese meadowsweet × 3, pink
- 5 Blue-stemmed goldenrod × 3, yellow
- 6 Hellebore 'Pink Frost' × 5, pink
- 7 Fawn lily 'White Beauty' × 7, white
- 8 Snowdrop × 12, white
Why this plant
- The only plant grown for its leaves. Leaf lasts all season, where a flower lasts a few weeks.
Why here
- Anchors a back corner. At 3 ft it is one of the taller plants here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to blue-stemmed goldenrod (2½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- One plant, alone. A feature plant is seen as an object, and needs clear ground around it.
Why now
- Here for its leaves, spring to frost. They cover the 7 weeks between early March and late November when nothing on the plan is in flower.
Planned as an English border: 5 of the 5 groups (100%) are drifts, longer along the bed than they are deep. The scheme leans cool (blue and pink) and uses yellow for warmth, with tan and white to calm things between them. Leadwort and moor grass 'Greenlee' finish the front edge.
The planner's own design check: 15 Excellent, 1 Good, 1 Satisfactory. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where southern shield fern goes in a border
At 3 ft it belongs in the middle of a bed. In the planner's ten height classes it is medium tall (2½ to 3 ft).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
A fast, forgiving fern where summers are long and hot. It spreads steadily into a soft, waist-high mass.
- Ferns for hot climates
- Massing under trees
- Sunny spots with moisture
What to plant with southern shield fern
Plants recorded as good partners for it, and what each pairing does:
- Cast iron plant: bold leaves against its fine ones.
- Lilyturf: adds the flowers, early August to mid September; low enough (16 in) to stand in front of it.
- Hosta: bold leaves against its fine ones; low enough (18 in) to stand in front of it.
Questions about southern shield fern
Does southern shield fern need sun or shade?
Southern shield fern grows in part sun (4 to 6 hours of sun, including some afternoon sun), part shade (2 to 4 hours of sun, mostly in the morning) and shade (less than 2 hours of direct sun, or bright dappled light). It is one of the few that also put up with deep shade.
It wants ordinary well-drained soil, of average fertility, and a good soak in dry spells.
What zones does southern shield fern grow in?
USDA zones 7 to 10. It is hardy to zone 7, which means it survives winter nights down to about 10 °F (−12 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
How far apart should southern shield fern be planted?
2½ ft (75 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 3 ft (90 cm), so a group knits into one patch.
It grows 3 ft (90 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many southern shield fern plants do I need?
At 2½ ft apart, set out in staggered rows:
- 2 to fill 10 square feet (about 1 m²)
- 5 for a single row 10 ft (3 m) long
- 6 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used one in one group.
Is southern shield fern poisonous to dogs and cats?
No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.
"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.
Is there a native plant like southern shield fern?
Southern shield fern is not native to North America. These North American natives come closest to doing its job:
- Male fern: the same job in a bed and the same size; medium leaves, not fine.
- Silvery glade fern: the same job in a bed; 6 in narrower, medium leaves, not fine.
- Victorian lady fern: the same job in a bed; 6 in shorter, 12 in narrower.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
Do deer eat southern shield fern?
Mostly not. NC State lists it as resistant to deer and rabbits. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.
Will southern shield fern spread?
It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads by underground runners and can crowd its neighbours. Dig out the edges or divide every 2 to 3 years.
What does southern shield fern look like in winter?
Southern shield fern dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
More Thelypteris
- Marsh fern Thelypteris palustris
- New York fern Thelypteris noveboracensis
In these guides
Every fact on record
- Type
- Fern
- Size
- 3 ft (90 cm) tall, 3 ft (90 cm) wide
- Plant
- 2½ ft (75 cm) apart
- Height class
- Medium tall (2½ to 3 ft)
- Place in the bed
- Middle
- Flowers
- None: grown for its foliage
- Leaves
- Fine texture, herbaceous; green
- Shape
- Arching, spreading
- Hardy in
- USDA zones 7 to 10
- Light
- Part sun, part shade, shade
- Soil
- Average, well-drained
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Aspleniaceae
- Stands up to
- Deer, rabbits, heat, humidity, deep shade
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.