A friend tells me she has had a horrible time getting Japanese Forest grass (Hakonechloa macra ‘Aureola’, below) to live in her garden, and she wonders how it is possible that mine flourishes. I’m reluctant to tell her that I’ve done nothing special to encourage it. It just grows, though it takes a few years to get going after it’s planted.
In fact, I planted a few pots of Forest grass earlier this spring beneath the shallow rooted, moisture sucking European beech (Fagus sylvatica ‘Purpurea’) in the front yard, and unsurprisingly these have been slow to catch on. They haven’t died, and I don’t expect they will, but the grass would prefer more moisture and it will take a few years longer under the beech to gain a solid foothold.
A few years ago I divided a large clump of Forest grass growing along the stream in the rear garden to transplant under a wide spreading Seven Son tree (Heptacodium miconiodes). The transplant took well, but then the tree was toppled in a summer storm last year. The red horsechestnut (Aesculus x carnea) that was planted in its place is considerably smaller, and its shade is not yet sufficient to shelter the Forest grass. So, it’s showing the stress of too much sun for now, but I expect that when the horsechestnut grows a bit larger in the next few years the grass will get along just fine.
I often find it difficult to define exactly what conditions most benefit a plant that is thriving, but two large clumps of Japanese Forest grass are shaded for at least half of the day, and both are protected from the hot, late afternoon sun. The one by the stream is more shaded, and perhaps the soil is cooled and slightly more moist beside the rubber lined stream. The other vigorous clump is in a sunnier spot, and under an upright growing Japanese maple (Acer palmatum ‘Okushimo’) so that the soil is considerably drier.
So, other than a clear preference for a half day’s shade, I haven’t a clue what makes Japanese Forest grass happy. To advise, I’d guess that a deep, moist, but well drained soil is preferred rather than root infested, dry shade, but this description goes for just about any plant, and it’s rarely found and so fairly worthless. I suppose that regular irrigation will solve some of the dry shade issues, but I never water, and Forest grass seems to do just fine without as long as you have a little patience for a year or two after planting.
The reason for growing Japanese Forest grass is quite simple, and there’s hardly another plant for shade that works so well. Any place where a hosta works, it’s ideal, with the added benefit that deer leave it alone. Since Forest grass grows only about a foot tall it belongs at the front and edge of a planting bed, and its muted gold foliage combines well with green foliage. It’s not so bright as to clash with most flowers, and even if it did the blooms fade quickly and the colorful foliage looks delightful for months. I don’t think I’d plant Forest grass beside a mass of pink flowered impatiens, but the narrow, gold striped foliage is a wonderful textural contrast to just about any broadleafed plant, and it is delightful planted beside any of the large leafed hostas.
I’m not as enthusiastic about other varieties of Forest grass, though they have their charms. ‘All Gold’ looks a bit faded to me, and the mixed colors of the foliage of ‘Beni-Kaze’ are a great idea, but it looks a little off to me. With irrigation I suspect that both will give a better impression, but to me ‘Aureola’ is still the better plant. My only problem with Forest grass is that it grows a bit too vigorously, and my wife insists on chopping it back off the garden’s paths. Japanese Forest grass has a graceful, arching habit that doesn’t take well to pruning, and it works perfectly to gently flop over the edge of a stone pathway. If I can only convince my wife.