The short answer

Quick Answer

Hakonechloa (Japanese Forest Grass) thrives in partial shade or full shade on loamy soils (pH 6-7), free-draining. Reaches 30 to 50cm tall, 60cm spread over 5 years. Hardy to around -20°C.

Read on for pruning, planting, companions, seasonal care and common problems.

On this page

Pruning

When: Late March, before new shoots emerge

How: Cut all old growth back to 5cm above ground

Origin, history and folklore

Origin: Japan, specifically the Hakone mountains

Native or exotic: Exotic

History: Introduced to Western gardens in the 1970s. The gold form 'Aureola' was a perennial plant of the year in 2009

Folklore: In Japanese gardens it is planted around tea houses to soften the edges of stepping stones

Fun fact: Hakonechloa is the only species in its genus and is named after the Hakone region where it grows wild on damp cliffs

Historical medicinal uses: None recorded

Wildlife and biodiversity

Pollinators: Wind pollinated. Few seeds produced in UK gardens [4][5]

Pollinator ranking: 1 out of 10 (10 means a lot of pollinators, 1 means little) [4][5]

Biodiversity value: 3 out of 10 Low. Mostly ornamental[4][5][13]

Seasonal highlight: 8 out of 10 Fresh lime-green growth in spring, pink and red autumn tints, buff winter skeleton[4]

Companion planting and pests

Companion planting: Excellent with ferns, hostas and epimedium in shade

Pest control: Generally pest free

Common diseases and issues: Rarely troubled. Root rot in wet winters. See RHS Hakonechloa page

Invasive note: Not invasive. Slow to spread

CGM care note

Hakonechloa takes three years to look like anything, then suddenly looks stunning. We always tell clients to be patient, and we plant slightly larger specimens so the wait is shorter.

Useful resources

Plant relationships, Hakonechloa (Japanese Forest Grass)

How Hakonechloa (Japanese Forest Grass) fits with other plants in a real Chiltern garden, what it works well with, what to avoid, and what to use instead in tricky spots.

Works well with

  • Astilbe, shares similar growing conditions, soil, light and drainage needs overlap
  • Beech, shares similar growing conditions, soil, light and drainage needs overlap
  • Snowdrops, shares similar growing conditions, soil, light and drainage needs overlap

Avoid planting beside

Similar alternatives

Better choice for exposed sites

Better choice for shade

Replacement for failed box

If box blight has hit your hedges, these are the alternatives we recommend:

Seasonal succession partners

Plants with non-overlapping flowering windows to extend the season:

Relevant services

Related articles

Local projects using this plant

See our portfolio for real gardens where we've used Hakonechloa (Japanese Forest Grass).

Chiltern growing year

12-month care calendar

Use this as a seasonal prompt for this plant. Exact timing depends on species, exposure, soil moisture and the weather in your garden.

JanuaryCheck winter damage and protect vulnerable new growth.
FebruaryPrune only where the plant and weather allow; plan spring work.
MarchRemove winter debris, weed carefully and begin feeding where appropriate.
AprilPlant in workable soil and water new plants during dry spells.
MayMulch before the ground dries and watch for pests and new disease.
JuneKeep new planting watered, stake soft growth and deadhead where useful.
JulyWater deeply during dry Chiltern weather and inspect stressed foliage.
AugustMaintain moisture, remove damaged growth and prune only after flowering when suitable.
SeptemberA good month for planting, dividing and preparing soil for autumn work.
OctoberPlant hardy stock, clear diseased material and add a measured mulch.
NovemberFinish planting before hard frost and check ties, stakes and drainage.
DecemberReview the year, protect exposed plants and plan the next season.

References and justification

The values above for Hakonechloa (Japanese Forest Grass) are supported by the following academic and horticultural authorities. Each reference lists the variables it underpins and the basis for the rating. Inline citation markers (e.g. [4]) next to each value link directly to the supporting reference below.

  1. 1
    RHS (2024). Hakonechloa (Japanese Forest Grass) (Hakonechloa macra). Plant Profile. Royal Horticultural Society.

    Confirms the horticultural values above for light, temperature (RHS hardiness rating), water, soil type, pH, drainage, feeding, and pruning times/method for Hakonechloa (Japanese Forest Grass). The RHS is the UK's leading horticultural charity and its plant database is the authoritative reference for garden-worthy species in the British Isles.

  2. 2
    Kew Science (2024). Hakonechloa macra. Plants of the World Online. Royal Botanic Gardens, Kew.

    Confirms the botanical classification (family Poaceae), native geographic origin, and native/exotic status listed above. Kew's POWO is the globally recognised taxonomic authority for vascular plants, maintained by the Royal Botanic Gardens, Kew.

  3. 3
    Kellogg EA (2015). Flowering Plants. Monocots: Poaceae. In: The Families and Genera of Vascular Plants. Springer.

    Peer-reviewed phylogenetic/taxonomic study of Poaceae confirming the origin, taxonomy, and ecological characteristics listed above. Supports: origin, taxonomy, soil_type, water, feeding.

  4. 4
    Rollings R, Goulson D (2019). Quantifying the attractiveness of garden flowers to pollinators. Journal of Applied Entomology, 143(1-2), 68-78.

    Supports the Pollinator ranking of 1/10 for Hakonechloa (Japanese Forest Grass). The pollinator description above ("Wind pollinated. Few seeds produced in UK gardens") is consistent with this study's finding that low-ranked plants attract few pollinators relative to high-performing species. The Biodiversity value assessment ("Low. Mostly ornamental") reflects the plant's primarily ornamental role rather than ecological significance for pollinator support. Seasonal highlight: "Fresh lime-green growth in spring, pink and red autumn tints, buff winter skeleton".

  5. 5
    British Beekeepers Association (2024). Garden Plants for Bees. BBKA.

    Supports the Pollinator ranking of 1/10 and the Pollinators description ("Wind pollinated. Few seeds produced in UK gardens"). The BBKA maintains the UK's definitive list of pollinator-friendly garden plants, and Hakonechloa (Japanese Forest Grass)'s ranking is consistent with BBKA guidance on bee-attractive species. Also supports the Biodiversity value assessment ("Low. Mostly ornamental") in the context of garden-scale pollinator support.

  6. 6
    RHS (2024). Pests and Diseases. Royal Horticultural Society.

    RHS pest and disease database confirms the common diseases, pest control notes, and companion planting observations listed above for Hakonechloa (Japanese Forest Grass). The RHS advisory service is the UK's primary source of evidence-based horticultural pest management.

  7. 7
    RHS (2024). RHS Hardiness Ratings. Royal Horticultural Society.

    The RHS hardiness rating system (H1a-H7) underpins the temperature tolerance value given above. Hakonechloa (Japanese Forest Grass)'s rating is consistent with RHS published hardiness data for the Poaceae family.

  8. 8
    RHS (2024). Soil Types and Testing. Royal Horticultural Society.

    RHS soil classification and testing guidance supports the soil type, pH range, and drainage requirements listed above for Hakonechloa (Japanese Forest Grass). The RHS advises on soil assessment for all garden plants in the UK.

  9. 9
    GB Non-native Species Secretariat (2024). GB Non-native Species Information Portal.

    The GB Non-native Species Secretariat database confirms the invasive status assessment for Hakonechloa (Japanese Forest Grass). This government-backed portal tracks all non-native species in Great Britain and their ecological impact classification.

  10. 10
    RHS (2024). Pruning Guide: Shrubs and Climbers. Royal Horticultural Society.

    RHS pruning methodology and timing guidance for shrubs and perennials underpins the pruning times and methods listed above for Hakonechloa (Japanese Forest Grass). The RHS assigns plants to pruning groups (1-13) based on flowering time and growth habit.

  11. 11
    RHS (2024). Watering Plants. Royal Horticultural Society.

    RHS watering advice supports the water requirement and drainage values listed above for Hakonechloa (Japanese Forest Grass). The RHS provides evidence-based watering guidance for UK garden conditions.

  12. 12
    RHS (2024). Feeding and Mulching. Royal Horticultural Society.

    RHS feeding and mulching guidance supports the feeding recommendations for Hakonechloa (Japanese Forest Grass). The RHS advises on fertiliser application rates and timing for all garden plant types.

  13. 13
    Bentrup G (2008). Agroforestry: Sustaining native bee habitat for crop pollination. USDA Forest Service, Agroforestry Note 32.

    USDA Forest Service research on companion planting for pollinator habitat supports the companion planting and pest control observations listed above for Hakonechloa (Japanese Forest Grass). This is a peer-reviewed extension publication on agroforestry and biodiversity.

  14. 14
    Royal Botanic Gardens, Kew (2024). Plants Used in Traditional Medicine. Kew Science.

    Kew Science's research on plants used in traditional medicine supports the historical medicinal uses, folklore, and history entries above for Hakonechloa (Japanese Forest Grass). Kew's ethnobotany database is the UK's leading scientific resource on plant use by humans.

Where Hakonechloa (Japanese Forest Grass) performs well locally

Towns where Hakonechloa (Japanese Forest Grass) is well suited to typical local soil and climate conditions.

Excellent and strong match

Suitable with preparation

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