Japanese catmint
Nepeta subsessilis · Lamiaceae
Glossy, dark green leaves and upright stems with large, tubular, violet-blue flowers, bigger than those of any other catmint.
- Size
- 2½ ft tall, 24 in wide
- Zones
- 4 to 8
- Light
- Full sun to part shade
- Flowers
- Late June to late August
- Pets
- Not checked
- Job in a bed
- Drift
A bed built around Japanese catmint
The planner designed this bed around Japanese catmint when this page was made: a 12 × 6 ft (3.7 × 1.8 m) cottage garden in zone 6, part sun. It chose the other plants from the 708 that suit those conditions, and says below why Japanese catmint stands where it does.
The plants
- 1 Japanese catmint × 1, blue
- 2 Creeping mahonia × 5, yellow
- 3 Mouse-ear coreopsis 'Nana' × 21, yellow
- 4 Japanese anemone 'Honorine Jobert' × 3, white
- 5 White snakeroot 'Chocolate' × 4, white
- 6 Inkberry 'Gem Box' × 1, dark green leaves
- 7 Snowdrop × 5, white
- 8 Red spider lily × 7, red
Why this plant
- The only spires. The others are dense clusters, daisies, open bowls and others. Shape reads at a distance, where colours blur.
- The only blue. The one cool colour: every other flower here is hot or neutral.
Why here
- In the middle. At 2½ ft it is the step between mouse-ear coreopsis 'Nana' (8 in) in front and Japanese anemone 'Honorine Jobert' (4 ft) behind: each is seen over the one before.
- One plant. Three or more is usual for a plant of this kind, and reads better.
Why now
- In flower for 9 weeks. From late June to late August.
- Fills a gap. For 8 of those weeks nothing else on the plan is in flower.
Planned as a cottage garden: 35 of the 35 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. The scheme leans hot (yellow and red) and uses blue for relief, with white to calm things between them. Mouse-ear coreopsis 'Nana' repeats along the bed to tie it together.
The planner's own design check: 12 Excellent, 4 Good, 1 Satisfactory.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where Japanese catmint 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.
The catmint for moist soil and part shade, where the grey-leaved kinds rot. It stands upright and gives blue spires among hostas and astilbes.
- Blue spires in part shade
- Moist borders
- Bees and butterflies
What to plant with Japanese catmint
Plants recorded as good partners for it, and what each pairing does:
- Astilbe: in flower together for four weeks, from late June; happy in the same moist soil.
- Lady's mantle: in flower together for two weeks, from late June; a low mound at the foot of its spires; happy in the same moist soil.
- Japanese forest grass: its green leaves are a setting for the flowers, before and after; happy in the same moist soil.
Questions about Japanese catmint
Does Japanese catmint need sun or shade?
Japanese catmint grows in full sun (6 or more hours of direct sun a day), part sun (4 to 6 hours of sun, including some afternoon sun) and part shade (2 to 4 hours of sun, mostly in the morning).
It wants soil that stays evenly moist, rich in organic matter, and a good soak in dry spells.
What zones does Japanese catmint grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 8 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.
When does Japanese catmint flower in my zone?
In zone 5 it flowers late June to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 4 | Early July to late August |
|---|---|
| Zone 5 | Late June to late August |
| Zone 6 | Late June to late August |
| Zone 7 | Late June to mid August |
| Zone 8 | 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 Japanese catmint be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.
It grows 2½ ft (70 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many Japanese catmint plants do I need?
At 18 in apart, set out in staggered rows:
- 5 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 17 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 there a native plant like Japanese catmint?
Japanese catmint is not native to North America. These North American natives come closest to doing its job:
- Bee balm 'Purple Rooster': the same job in a bed and the same flowering time; 8 in taller, purple, not blue.
- Garden phlox 'Bright Eyes': the same job in a bed, the same size and the same flowering time; pink, not blue.
- Obedient plant 'Miss Manners': the same job in a bed, the same size and the same flowering time; white, not blue.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after Japanese catmint?
Japanese catmint is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:
- Garden chrysanthemum: from mid September to late October, 24 in tall.
- Japanese anemone: from mid August to early October, 3 ft tall.
- Sedum 'Autumn Joy': from mid August to mid October, 24 in tall.
What does Japanese catmint look like in winter?
Japanese catmint 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 Nepeta
- Catmint 'Cat's Meow' Nepeta x faassenii 'Cat's Meow'
- Catmint 'Junior Walker' Nepeta x faassenii 'Junior Walker'
- Catmint 'Purrsian Blue' Nepeta x faassenii 'Purrsian Blue'
- Catmint 'Six Hills Giant' Nepeta 'Six Hills Giant'
- Catmint 'Walker's Low' Nepeta x faassenii
- Catnip Nepeta cataria
In these guides
Every fact on record
- Type
- Perennial
- Size
- 2½ ft (70 cm) tall, 24 in (60 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Medium (24 in to 2½ ft)
- Place in the bed
- Middle
- Flowers
- Late June to late August; upright spires; blue, purple
- Leaves
- Medium texture, herbaceous; dark green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun, part sun, part shade
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Lamiaceae
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.