Montbretia
Crocosmia x crocosmiiflora · Iridaceae
Arching sprays of small, orange, red or yellow, funnel-shaped flowers above sword-like leaves in late summer. The corms multiply quickly.
- Size
- 2½ ft tall, 12 in wide
- Zones
- 6 to 9
- Light
- Full sun to part sun
- Flowers
- Mid July to late August
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around montbretia
The planner designed this bed around montbretia when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why montbretia stands where it does.
The plants
- 1 Dianthus 'Kahori' × 3, pink
- 2 Leadwort × 15, blue
- 3 Foxglove beardtongue × 3, white
- 4 Tatarian aster 'Jindai' × 4, purple
- 5 Globe arborvitae 'Danica' × 1, green leaves
- 6 Caucasian scabious 'Fama' × 3, blue
- 7 Montbretia × 3, yellow
- 8 Schubert's allium × 2, pink
Why this plant
- The only airy sprays. The others are open bowls, dense clusters, spires and others. Shape reads at a distance, where colours blur.
- The only yellow. The one hot colour: every other flower here is cool or neutral.
Why here
- In the middle. At 2½ ft it is seen over dianthus 'Kahori' (8 in) in front of it.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for 8 weeks. From mid July to late August.
- Part of the bed's peak. With dianthus 'Kahori', leadwort and caucasian scabious 'Fama' in early August: 4 kinds at once. No week has more.
Planned as an English border: 5 of the 6 groups (83%) are drifts, longer along the bed than they are deep. Leadwort repeats along the bed to tie it together. There is more leadwort than anything else, 15 plants in all.
The planner's own design check: 12 Excellent, 4 Good, 1 Satisfactory. It flags one thing to watch: Montbretia spreads aggressively. Each plant's details say more.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where montbretia goes in a border
At 2½ ft it belongs in the middle of a bed. In the planner's ten height classes it is medium (24 in to 2½ ft).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
A warm glow of orange among the yellows of late summer. It spreads fast in mild, moist climates; the named, larger-flowered forms, such as 'Lucifer', are easier to keep in bounds.
- Hot colours for late summer
- Cut flowers
- Hummingbird gardens
What to plant with montbretia
Plants recorded as good partners for it, and what each pairing does:
- Black-eyed Susan: in flower together for eight weeks, from mid July; grows up in time to hide its dying leaves.
- Daylily: in flower together for five weeks, from mid July; grows up in time to hide its dying leaves.
- Dwarf fountain grass 'Hameln': in flower together for six weeks, from late July; grows up in time to hide its dying leaves.
Questions about montbretia
Does montbretia need sun or shade?
Montbretia 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 montbretia grow in?
USDA zones 6 to 9. It is hardy to zone 6, which means it survives winter nights down to about 0 °F (−18 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does montbretia flower in my zone?
In zone 5 it flowers mid July to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 6 | Mid July to late August |
|---|---|
| Zone 7 | Early July to late August |
| Zone 8 | Early July to late August |
| Zone 9 | Late June to mid August |
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 montbretia be planted?
6 in (15 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 12 in (30 cm), so a group knits into one patch.
It grows 2½ ft (75 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many montbretia plants do I need?
At 6 in apart, set out in staggered rows:
- 48 to fill 10 square feet (about 1 m²)
- 21 for a single row 10 ft (3 m) long
- 153 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 three in one group.
Is montbretia 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.
Will montbretia spread?
It spreads sideways, by runners or roots; the risk of it taking over is high. The corms multiply fast into dense stands that crowd out other plants. It has escaped into the wild along the Pacific coast and in the Southeast. Never dump surplus corms.
What can I plant to hide montbretia's leaves after it flowers?
A bulb's leaves have to be left to yellow for about six weeks after flowering, to feed next year's flowers. Plant it among perennials that come up late and spread wide, and they grow over the leaves as they fade:
- Daylily: 2½ ft tall and 24 in wide, a recorded partner, in flower late June to early August.
- Catmint 'Walker's Low': 24 in tall and 2½ ft wide, in flower mid May to mid September.
- Garden chrysanthemum: 24 in tall and 24 in wide, in flower mid September to late October.
What does montbretia look like in winter?
Montbretia is underground: it dies back after flowering and waits as a bulb until spring. Mark where it is, so a fork does not find it first.
More Crocosmia
- Crocosmia 'Emily McKenzie' Crocosmia x crocosmiiflora 'Emily McKenzie'
- Crocosmia 'Lucifer' Crocosmia 'Lucifer'
In these guides
Every fact on record
- Type
- Bulb
- Size
- 2½ ft (75 cm) tall, 12 in (30 cm) wide
- Plant
- 6 in (15 cm) apart
- Height class
- Medium (24 in to 2½ ft)
- Place in the bed
- Middle
- Flowers
- Mid July to late August; airy sprays; orange, red, yellow
- Leaves
- Medium texture, herbaceous; green
- Shape
- Arching, spreading
- Hardy in
- USDA zones 6 to 9
- Light
- Full sun, part sun
- Soil
- Average, evenly moist
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Iridaceae
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.