Propagating Hakonechloa, and a new planting scheme

Hakonechloa, or Japanese Forest Grass is stylish and attractive, and most any garden will benefit with a planting of thjis award winning plants. It even thrives in the dry shade garden, but plants are expensive, and the best cultivars often sell out quickly. If you have a mature clump, you can divide it, often resulting in dozens of new plants, but this is a task best undertaken during a brief window of 2 weeks in mid spring, just as the plants are exiting dormancy, and beginning to grow new growth.

 If you’re like me, you dream of having sweeping drifts of perennials and other herbaceous plants, interplanted with bulbs and the occasional annual, inspired by the current trend of more natural landscape schemes, such as those designed by Piet Oudolf and his contemporaries, but the sheer volume of plants required to achieve such looks can be out of reach, financially, for most of us. It’s been my long-term goad to redesign our back yard ( garden) to slowly eliminate the lawn and to replace it with such a planting scheme, but, such aggressive design takes time, but perhaps, not as much money as I might have dished out, simple because I am propagating many of my own plants which are either already in the garden, or, from seed and cuttings.

As if I have nothing better to do, I am in the middle of redesigning a large part of our property – essentially, the entire back 2 acres which we can see from the house. All this amidst preparing for a large presentation next week at HOWlive in San Francisco, an even bigger app design project at work that every child under ten around the world will want next Christmas, and, yes – planting the summer garden, containers and vegetables. So naturally, it’s the perfect time to propagate some plant material, right?

Dig a large clump of Hakonechloa early in the spring just after the new growth begins. This is the only time one should attempt to divide this valuable plant. One mature clump however, may provide you with a dozen or more divisions.

Propagating ones one perennials is extremely cost effective, and as my design plants call for dozens of Hakonechloa, or Japanese River Grass, I’d much rather propagate my own, rather than dish out $18.95 for a one gallon pot, which is, after all, just a liner ( division) from someone else. My process started early this spring, in early May, for Hakenochloa must be divided after it has started new growth in the spring, but not any later than late June, as its rhizomes form roots shorty after extending, if not at the same time.

If one attempts division too early in the spring, or too late in the summer, the resulting divisions would need to be larger as the plant, not unlike bamboo, forms long, trailing growth, which all connects back to the central plant. The problem is that these long growths have no roots, as the plant grows and divides much like a spider wed, extending rhizomes during the summer, producing foliage, but the roots on these extensions don’t emerge until the following spring, just as the plant starts to extend new rhizomes, and this is the 2 week window when the plant can be divided into many small plants. Just as the new growth is 2 or 3 inches tall.

Bring your clump of grass up close, on a table or a potting bench, and carefully start to remove the soil. Root systems on Hakenochloa are weak, and most likely, your soil will drop off cleanly, leaving a tangled web of rhizomes and sprouting stems. Now you can begin to divide the clump by cutting away sections with root systems on each one.

I dug up one of our larger golden Hakonechloa selections during the first week of May, just as the plant was starting into growth, and brought the entire clump into the greenhouse so that I could examine and divide it while it sat on the potting bench. In this way, I could carefully remove soil, and see exactly where I needed to snip apart the strong, bamboo-like extensions.

This section is almost too small to plant, as the runner only shows one root. It may fail, if potted up.

One needs to look carefully, tugging and pulling apart slowly the clump, looking for extensions that have both new growth as well as at least 3  or 4 growths. You will notice that some have no roots at all, and these I discard.

The root system on Hakonechloa is complex, and teh runners that connect each section are woody-like, and hard to cut – use garden Fiscar brand scissors or wire cutters, and cut segments carefully, looking for both roots and new growth on each section.

I use a commercial soiless mix, combined 50/50 with composted bark, a mix common in the nursery trade, but one that perennials and many seedling like, as it combines peat, bark and lots of air space for oxygen. I pot up each division into 5 inch pots, paying close attention to the planting depth, keeping the new growth and roots at exactly the same depth as when the mother plant was growing outdoors.

Once potted, I place the trays on a bench in the greenhouse for a week or two, as full sun will injure the new growth, and I fertilize with a 9-17-49 Fertilizer to stimulate root growth, which is essential at this stage, as Hakonechloa are slow at rooting, even during their most aggressive growth spurt of the year. Divisions should spend time under shade cloth or outdoors in a protected, cool area for 6 – 8 weeks, to allow roots to fill the container before planting out in the garden.

Plants in June, are well rooted and ready to plant out into the garden.

My planting scheme calls for 48 Hakenochloa, as a more natural blended garden requires large drifts of grasses for textural interest and color.  This particular design uses golden Hakeonochloa in a meandering ‘stream-like’ planting, which runs through the center of this large new bed. Hakenochloa, when mature, appears fluid – the foliage lies in one direction, providing a flowing texture which few plants can offer, but to achieve this effect, one does need multiple plants. You can do the math, as I saw plants at our local nursery no larger than my divisions for $18.95. Combined with my seed raised perennials such as Rogersia, Anemone and Primula species, you can see how dollars can add up. I’ll share more about my design plans for the largest part of my garden, until then, back to work. There is much more to plant.

Primula seedlings and Rogersia seedlings ready for transplanting. These plants had a long journey, spending a winter out in the cold frame being stratified, and then time spend being grown on in the greenhouse. Some of these seeds we wild collected while hiking in the Alps two years ago ( the Primula elatior). I imagine large swaths of P. elatior, as we saw them in the wild, and then interplanted with perennials, which will provide interest throughout the rest of the year.

So this is where my scheme becomes weird – I am combining Asiatic primula, such as this Tibetan native Primula denticulata in the same planting scheme, along with other Asian herbaceous plants, with European natives. Shhh, don’t tell the purists! My theory on landscape design sometimes clashes with those who are more formally trained, but I support the global collection sometimes, yet as I mature, I like to keep things more natural.

I am planting a few dozen seedlings of Anemone hupehensis, formally Anemone japonica, (or A. hupehensis var. japonica) to provide an autumnal display. These need a year in the garden before they will bloom, but I can wait. I just love their graceful wands of pink anemone blossoms, and interplanted like this, they should make this bed  a standout in the garden come late September.  Starting these plants from seed, again, saves on plenty of money, as one autumnal Anemone can cost $18 -$20 dollars. I have 3 flats of 36 plants each. Nice.

The final planting scheme, which is misleading here, as the plants appear too close together, but remember that the Primula will bloom early ( the P. denticulata will bloom in March), followed by the P. elatior. I also planted 48 Columbine ( ‘Songbird Series’) which I also started from seed, which will bloom in June. The Anemone will start blooming in late August and September, and the grasses will carry the scheme through the summer, and even the winter.

Another view looking north. Ignore the wire in the background ( and the little bog garden that our friend Glen Lord  gave us – it’s full of Pitcher Plants, which are just beginning to bloom!), the wire is for our tortoise, so that he can dine on the lawn.

Oh, and in case you are wondering what Rogersia is – here is a brief intro: ( I know, sometimes I forget, assuming that everyone is familiar with all of these plants that I yak about!). Above is a photo I took today of some Rogerisa which I started from seed five years ago. I was introduced to Rogersia many, many years ago, while still in high school, while working as a gardener at the Stoddard Estate, a Fletcher Steele designed garden. It can be difficult to find, unless you look for it at specialty nurseries. Rogersia is not rare, just not common.

You generally will find two species: Rogersia aesculifolia ( because, this species has foliage which looks very much like Aesculus, or the common Horse Chestnut), and R. pinnata, which is what I propagated this year from seed. The seed is quite tiny, and challenging to germinate, so I don’t expect many of you to try growing it this way, but it is by far the most economical way to grow this slow growing plants, as, like many good plants, Rogersia are expensive. At $35 for a one gallon container, I try to add one or two of he red-leaved cultivars to my collection each year, but from seed, the plain green is just as attractive.  Architectural and long-lived, it sits high on my must-have plant list for shade gardens.