Feather reed grass 'Karl Foerster'
Calamagrostis x acutiflora 'Karl Foerster' · Poaceae Popular
A narrow, bolt-upright grass with feathery plumes that turn wheat-gold and stand through winter. Its seeds are sterile, so it stays where it is planted.
- Size
- 5 ft tall, 24 in wide
- Zones
- 4 to 9
- Light
- Full sun to part sun
- Flowers
- Late June to early October
- Pets
- No toxicity recorded
- Job in a bed
- Accent
A bed built around feather reed grass 'Karl Foerster'
The planner designed this bed around feather reed grass 'Karl Foerster' when this page was made: a 12 × 6 ft (3.7 × 1.8 m) contemporary bed in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why feather reed grass 'Karl Foerster' stands where it does.
The plants
- 1 Feather reed grass 'Karl Foerster' × 3, tan
- 2 Mouse-ear coreopsis 'Nana' × 8, yellow
- 3 Creeping phlox 'Emerald Blue' × 5, blue
- 4 Swamp milkweed 'Ice Ballet' × 3, white
- 5 Inkberry 'Gem Box' × 1, dark green leaves
- 6 Turtlehead 'Hot Lips' × 3, pink
- 7 Giant snowdrop × 8, white
Why this plant
- The only plumes. The others are daisies, open bowls, flat plates and others. Shape reads at a distance, where colours blur.
- The only tan. Tan sits between stronger colours and calms them.
- Part of the bed's structure. Shrubs and grasses keep their shape when the perennials die down. So does inkberry 'Gem Box'.
Why here
- Anchors a back corner. At 5 ft it is the tallest plant 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 turtlehead 'Hot Lips' (3 ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one clump. A single spire is too slight to hold a place alone, so here the accent is a clump.
Why now
- In flower for 16 weeks. From late June to early October.
- Closes the season. In its last week nothing else on the plan is in flower.
- Stands through winter. Left uncut, it holds its shape until March, when the perennials have gone.
Planned as a contemporary bed: 30 of the 30 plants that stand in groups (100%) are set out in a pattern with their neighbours: a straight row, a triangle, or five like the five on a dice. The flowers run from mid February to early October, but stop for 4 weeks from late March. The back corners are held by swamp milkweed 'Ice Ballet' and feather reed grass 'Karl Foerster', the tallest plants on the plan.
The planner's own design check: 11 Excellent, 4 Good, 2 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 feather reed grass 'Karl Foerster' goes in a border
At 5 ft it belongs at the back of a bed. In the planner's ten height classes it is tall (4 to 5 ft). It is airy enough to see through, so it can also come forward and veil what is behind it.
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
The most upright grass there is: a vertical line that stays put from June to February. Repeat single plants at intervals along the back of a bed to give it rhythm, as you would fence posts.
- A narrow vertical accent, even in a small bed
- Winter structure
- A see-through screen at the back
What to plant with feather reed grass 'Karl Foerster'
Plants recorded as good partners for it, and what each pairing does:
- Purple coneflower: in flower together for 11 weeks, from late June; low enough (3 ft) to stand in front of it.
- Black-eyed Susan: in flower together for 11 weeks, from mid July; low enough (24 in) to stand in front of it.
- Joe Pye weed 'Gateway': in flower together for eight weeks, from late July; bold leaves against its fine ones; happy in the same moist soil.
Choosing between it and a look-alike? Switchgrass 'Northwind' vs Feather reed grass 'Karl Foerster' and Feather reed grass 'Karl Foerster' vs Korean feather reed grass.
Questions about feather reed grass 'Karl Foerster'
Does feather reed grass 'Karl Foerster' need sun or shade?
Feather reed grass 'Karl Foerster' grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).
It wants soil that stays evenly moist, of average fertility, and a good soak in dry spells.
What zones does feather reed grass 'Karl Foerster' grow in?
USDA zones 4 to 9. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does feather reed grass 'Karl Foerster' flower in my zone?
In zone 5 it flowers late June to early October. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 4 | Late June to early October |
|---|---|
| Zone 5 | Late June to early October |
| Zone 6 | Late June to early October |
| Zone 7 | Mid June to early October |
| Zone 8 | Mid June to early October |
| Zone 9 | Early June to early October |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should feather reed grass 'Karl Foerster' be planted?
24 in (60 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.
It grows 5 ft (150 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many feather reed grass 'Karl Foerster' plants do I need?
At 24 in apart, set out in staggered rows:
- 3 to fill 10 square feet (about 1 m²)
- 6 for a single row 10 ft (3 m) long
- 10 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in one group.
Is feather reed grass 'Karl Foerster' 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 feather reed grass 'Karl Foerster'?
Feather reed grass 'Karl Foerster' is not native to North America. These North American natives come closest to doing its job:
- Switchgrass 'Northwind': the same job in a bed, the same size and the same colour; flowers early August to early October, wants average soil.
- Indian grass: the same job in a bed and the same colour; 12 in taller, flowers late August to early October.
- Culver's root: the same job in a bed and the same size; flowers early July to mid August, white or lavender, not tan.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after feather reed grass 'Karl Foerster'?
Feather reed grass 'Karl Foerster' is over by early October. These start as it finishes and carry the same spot on, so it never goes flat:
- Tatarian aster 'Jindai': from early October to early November, 4 ft tall.
- Chrysanthemum 'Sheffield Pink': from late September to early November, 2½ ft tall, to stand in front of it and cover its fading stems.
- Swamp sunflower: from late September to late October, 6½ ft tall.
What does feather reed grass 'Karl Foerster' look like in winter?
Feather reed grass 'Karl Foerster' turns the colour of straw and, left uncut, stands through the winter. Cut it down in late winter, before the new shoots come up.
More Calamagrostis
- Feather reed grass 'Avalanche' Calamagrostis x acutiflora 'Avalanche'
- Feather reed grass 'Overdam' Calamagrostis x acutiflora 'Overdam'
- Korean feather reed grass Calamagrostis brachytricha
In these guides
- Pet-safe plants for a sunny border
- Tall perennials and grasses for the back of a border
- Long-flowering plants: 12 weeks or more
Zone guides: Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8 · Zone 9
Every fact on record
- Type
- Grass
- Size
- 5 ft (150 cm) tall, 24 in (60 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Tall (4 to 5 ft)
- Place in the bed
- Back, or further forward: it is airy enough to see through
- Flowers
- Late June to early October; feathery plumes; tan
- Leaves
- Fine texture, herbaceous; green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 4 to 9
- Light
- Full sun, part sun
- Soil
- Average, evenly moist
- Water
- Moderate
- Feeding
- None needed
- Family
- Poaceae
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.