What is Japanese forest grass?
Japanese forest grass, also called Hakone grass (Hakonechloa macra), is a deciduous perennial grass native to the woodlands of Japan. It is prized for slender, arching leaves that cascade into a soft, flowing mound, often compared to bamboo foliage (see grasses that look like bamboo). Plants are typically 12 to 18 inches tall and about as wide, although some sources list taller sizes. It spreads slowly, and it is a good fit for part-shade and shade gardens.
Because it is deciduous, the leaves fade to a tan or buff in autumn and die back over winter, and new growth appears in spring.
Popular cultivars
- ‘All Gold’: bright golden-yellow foliage, one of the best-known choices for brightening shade.
- ‘Aureola’: variegated leaves with gold and green stripes; probably the most widely sold type.
- Green species form: the plain green Hakonechloa macra is a softer look and often a little more tolerant of sun.
- Sunflare and other newer selections: bi-color or colorful forms are sold by some nurseries.
Variegated and golden forms generally color best with some light, and green forms are less sensitive.
Light
Japanese forest grass does best in part shade or dappled shade. Most guidance for golden cultivars is:
- A little morning sun brightens the color.
- Protect it from hot afternoon sun, which can scorch the leaves, especially in warm climates.
- Very deep shade can dull gold forms toward lime green.
One nursery lists shade (under 4 hours of sun) to part sun (4 to 6 hours) as ideal and notes that full hot sun may scorch the foliage.
Soil and watering
It grows best in rich, organic, moist but well-drained soil with a slightly acidic to neutral pH. Avoid heavy clay that drains poorly, since waterlogged roots are a common cause of problems; if clay is all you have, choose from grasses that thrive in heavy clay soil instead. Where soil is heavy or sandy, mix in compost to improve texture and moisture retention.
Water regularly, especially during the first growing season and through hot summer spells. Established plants tolerate brief dry periods, but leaf tips brown if the soil dries out too much. If your site is naturally wet, check our notes on grasses for wet shade, since Hakone grass likes moisture but dislikes soggy conditions.
Planting and spacing
- Plant in spring or early fall.
- Space plants about 18 to 24 inches apart, closer if you want faster coverage (see our spacing guide).
- Set the crown at the same level as it was in the pot.
- Mulch with organic material to keep roots cool and hold moisture.
Hakone grass is slow to establish and fill in. Don’t expect a big mound in the first year.
Seasonal care and cutting back
Leave the old foliage standing through winter, since it protects the crown. In early spring, just before new shoots emerge, cut back the old growth to a few inches or to the ground. Some growers trim in late fall, but waiting until spring keeps the crown protected.
In zones 5 and 6, a layer of extra mulch in late fall is commonly advised for winter protection. Fertilizer is rarely necessary in good soil; if you feed, a light application of balanced or slow-release fertilizer in spring after growth begins is enough.
Dividing
Divide every two to four years in spring, when new growth is just starting. Dig up the clump, cut it into sections with a sharp spade or knife, and replant at once, watering well. Dividing is also the easiest way to get more plants; see how to divide and transplant ornamental grasses.
Growing in containers
Hakone grass is popular in pots, where its cascading habit spills over the edge. Use a good potting mix, keep it evenly moist, and feed more regularly than in the ground. Container plants are more exposed to winter cold, so in cold regions place the pot in a sheltered spot or protect it, as described in overwintering ornamental grasses.
Companion plants
The fine, flowing leaves pair well with bold shapes and colors:
- Hostas, especially blue or large-leaved types
- Heuchera (coral bells), particularly dark-leaved varieties
- Astilbe
- Ferns
- Small shrubs, where Hakone grass can be used as foreground planting
See more combinations in our guide to ornamental grasses for shade and part shade.
Troubleshooting
- Brown leaf tips or edges: usually dry soil, hot sun or both. Water more, mulch, and add afternoon shade.
- Washed-out or pale color: may be too much shade or too much harsh sun, depending on the cultivar.
- Slow growth: normal for the first few years. Make sure moisture and soil quality are good.
- Yellowing or rotting crown: poor drainage. Improve the soil or move the plant.
Hakone grass is generally described as resistant to pests, disease and deer; see deer-resistant grasses for shade for more on that. For a similar shade plant with more variety, try Carex varieties.