Oak fern
Gymnocarpium dryopteris ·
Small, delicate, triangular fronds of bright apple green, held flat on thin stems, forming a low carpet. A fern of cool northern woods.
- Size
- 10 in tall, 18 in wide
- Zones
- 2 to 7
- Light
- Part shade to shade
- Flowers
- Grown for its leaves
- Pets
- Not checked
- Job in a bed
- Carpet
A bed built around oak fern
The planner designed this bed around oak fern when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, part shade. It chose the other plants from the 513 that suit those conditions, and says below why oak fern stands where it does.
The plants
- 1 Oak fern × 18, green leaves
- 2 Wherry's foamflower × 8, white
- 3 Turtlehead 'Hot Lips' × 5, pink
- 4 Tall astilbe 'Superba' × 4, purple
- 5 Bleeding heart 'Gold Heart' × 1, pink
- 6 Snowdrop × 10, white
- 7 Striped squill × 12, blue
Why this plant
- The only plant grown for its leaves. Leaf lasts all season, where a flower lasts a few weeks.
- The only fine leaves here. The rest are medium. A change of leaf keeps plants distinct when nothing is in flower.
Why here
- Under the taller plants. It runs back between them as living mulch: there its job is to cover the soil, not to be looked at.
- 18 plants in 5 groups (5, 4, 3, 3 and 3). Seen again further along, the same plant ties the bed together.
Why now
- Here for its leaves, spring to frost. They cover the 15 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 bed is balanced: the left half carries 52% of the visual weight and the right half 48%. Oak fern is planted in five places along the bed, which gives it rhythm.
The planner's own design check: 12 Excellent, 2 Good, 3 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 oak fern goes in a border
At 10 in it belongs at the front of a bed. In the planner's ten height classes it is low (6 to 12 in).
Its job: carpet. A groundcover planted in threes and fives to cover the soil: along the front, and just behind it.
The brightest green in the shade garden, and a fine carpet under taller woodland plants. It needs cool, moist, acid soil, and fails in hot summers.
- Delicate groundcover for cool shade
- Under shrubs
- Northern woodland gardens
What to plant with oak fern
Plants recorded as good partners for it, and what each pairing does:
- Foamflower: adds the flowers, late April to late May; spires rising out of its mound; happy in the same moist soil.
- Wild ginger: bold leaves against its fine ones; low enough (6 in) to stand in front of it; happy in the same moist soil.
- Dwarf Solomon's seal: adds the flowers, early May to early June; happy in the same moist soil.
Questions about oak fern
Does oak fern need sun or shade?
Oak fern grows in 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 wants soil that stays evenly moist, rich in organic matter, and a good soak in dry spells.
What zones does oak fern grow in?
USDA zones 2 to 7. It is hardy to zone 2, which means it survives winter nights down to about −40 °F (−40 °C).
Above zone 7 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
How far apart should oak fern be planted?
12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 18 in (45 cm), so a group knits into one patch.
It grows 10 in (25 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many oak fern plants do I need?
At 12 in apart, set out in staggered rows:
- 12 to fill 10 square feet (about 1 m²)
- 11 for a single row 10 ft (3 m) long
- 38 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as threes and fives, along the front and just behind it.
In the bed above, the planner used 18 in five groups.
Is there a native plant like oak fern?
Oak fern is not native to North America. These North American natives come closest to doing its job:
- New York fern: the same job in a bed; 8 in taller, wants average soil.
- Rock polypody: the same job in a bed; 4 in narrower, medium leaves, not fine.
- Wild ginger: the same job in a bed; 4 in shorter, bold leaves, not fine.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What does oak fern look like in winter?
Oak 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.
In these guides
Every fact on record
- Type
- Fern (groundcover)
- Size
- 10 in (25 cm) tall, 18 in (45 cm) wide
- Plant
- 12 in (30 cm) apart
- Height class
- Low (6 to 12 in)
- Place in the bed
- Front
- Flowers
- None: grown for its foliage
- Leaves
- Fine texture, herbaceous; green
- Shape
- Mat-forming, spreading
- Hardy in
- USDA zones 2 to 7
- Light
- Part shade, shade
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- Light, in spring
Not yet checked against an outside reference: its figures rest on general horticultural knowledge. 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.