Proceed with caution

I don’t recall the exact timing, but it was probably twenty years ago when a fervor for ornamental grasses gripped the gardening world. At first I resisted, but slowly I was convinced to try a few in my garden that was just getting started. This seemed an inexpensive way to fill spaces quickly, and I was anxious to give the appearance of an established garden. I planted several types of miscanthus, a handful of fountain grasses, and northern sea oats and Japanese Forest grass in shady areas. Spots were found for Blue Dune grass (Elymus) and giant reed grass (Arundo donax), and blue fescue (Festuca glauca, below) was sprinkled in wherever a splash of color was needed.

At the time (before Google), information on most grasses was limited to a sentence or two in a nursery catalog describing the lovely seed heads, but there was no mention that some could be ruthless self-seeders. In my garden Blue Dune grass quickly became a scourge, not by seeding but by spreading below ground. Everywhere. In all directions. In a hurry. I tried digging, and digging more, but it stubbornly resisted until an herbicide finally brought it down. Good riddance, and a lesson learned to investigate before planting. For holding coastal sand dunes together in a storm this is probably a fine plant. In an ornamental garden, not so good. 

I planted all of the basic fountain grasses, and in a short time took a liking to the black fountain grass (Pennistem  alopecuroides ‘Moudry’, above) with stiff, black bottlebrush spikes. Its seed heads formed a month earlier, and they were showier than others. The foliage was a bit coarse, but it was an ideal size and it fit nicely into the garden. A year after planting I found a few seedlings nearby, but free plants are often a good thing, so some were left in place and others transplanted where they could be better enjoyed.

The following year there were more seedlings, and some that popped up in the lawn. Then a few were spied in the nearby field, and now it was becoming obvious that a demon was on the loose. Small seedlings were easily dug out of the garden, but more established clumps were sprayed with Roundup. I was careful to eliminate every trace of the grass I could find, and for years there was no sign of it in the neighborhood. Recently I’ve noticed a band of black fountain grass surrounding the farm pond just up the road, and though I’m confident that these did not originate from my garden I’ll work to eliminate this batch before it invades further.

I’ve also seen a problem with the common maiden grass (Miscanthus sinensis gracillimus) popping up at the wild edges of the garden, though variegated and dwarf maiden grasses have not been troublesome. I’ve had no problems with other grasses seeding, but through the years the garden has grown considerably more shady, and all but a few variegated leaf maiden grasses have faded away. Fountain grasses are more tolerant of the encroaching shade, but several are becoming more sparse each year.

Northern sea oats (Chasmanthium latifolium, above) thrives in shaded spots, and in moist soil it seeds thickly, though it does not spread far from the parent plant. I remove the seed heads when the plant goes dormant after November frosts, and this dependably manages the number of seedlings.

The gold leafed Japanese Forest grass (Hakonechloa macra ‘Aureola’, above) brightens any shady spot in the garden. I have never seen a seedling from a handful of plants in my garden, and it is much slower to spread than other grasses. This is a marvelous plant for part shade to part sun, but I recommend starting with a one gallon container or larger since Forest grass seems a bit touchy in smaller sizes that are often mail ordered. 

I prefer the contrasting green and gold stripes of ‘Aureola’ rather than the all gold leafed version that can look washed out to me. Japanese Forest grass’ seed heads (above) are unremarkable, but attractive in an understated manner.

It took a while for me to figure the ideal spot for blue fescue (Festuca glauca), well drained, but not too dry, and I lost a few plants early on. The small tuft of blue foliage seems an easy fit in the garden, but they are easily overwhelmed by neighboring plants. Several blue fescues have grown in the garden for ten years or more, and now they are only slightly larger than when they were first planted, so there is no danger that these will escape from the garden.

I suppose that I’ve come nearly full circle, from not caring a bit about grasses, to heartily accepting them, and then feeling some relief when a few succumbed to deepening shade. Still, there are many fine grasses, and I don’t intend to scare you away from planting them. Earlier this summer I planted a variegated giant reed grass that I expect within a few years will tower over the damp rear garden. I planted a few more blue fescues, and divided two whopping clumps, one of a gold carex, and the other Japanese Forest grass.

I’ve found that divisions transplant easily, but planting of most grasses is best undertaken in the spring or summer rather than in autumn when roots are slow to grow and new plants are often injured by wet winters. And, I suggest checking before you plant to determine whether your choice will be a problem in seeding itself about, though most are safe and excellent choices.

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5 thoughts on “Proceed with caution

  1. Dave….Like you, I was tempted a few years ago to try some “grasses” around our shady back yard. I could have predicted that they would eventually die because of the deep shade. They were cheapos from a local home center. But we’ve always wanted to try again and would appreciate your recommendations. Unfortunately, most of my backyard is in shade, the soil is dense clay (which I can improve), but at least I wanted to try a grass that might succeed without taking over the neighborhood. So that we’re on the same page, pls tell us if Meadows Farms on Rte 50 carries any of these during the year. Standing by. (Oh, I forgot. Are all grasses attractive to deer? We do have a problem in that area and spraying doesn’t seem to be all that effective at keeping the nibblers away.)

    • Inventory of grasses is sparse now, but the garden centers stock a selection of grasses from mid spring into the autumn. Deer do not bother most grasses at all, though I spray the Forest grass and blue fescue because they seem like they might be more tasty.

  2. I had a similar experience with fountain grasses. I planted a border along my fence which has done spectacularly. However, I live next to public land and a stream. I’ve noticed some sizable clumps growing along the stream and I’m certain they are escapees from my garden. This area is frequented by deer, so I’m hoping they keep it under control otherwise I’m concerned I will have started an ecological disaster!

    • I’ve found that deer are reluctant to eat most grasses, so it’s unlikely that they’ll correct the problem. Anyway, it will probably not be an ecological disaster, only a small one.

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