Muhly Grass (Muhlenbergia capillaris)

Muhly Grass
(Muhlenbergia capillaris)
As fall approaches plants go on sale. The lower prices give us the opportunity to take chances with plants that are questionable for our area or the situation in which we wish to grow them. We will be experimenting with a new one this fall.
There is a section on the embankment that we have under cultivation in the area across from Harley-Davidson (aka John’s garden) where the slope is steep. There is a seep at the bottom of the slope and ‘Strawberries and Cream’ ( Phalaris arundinacea ‘Strawberries And Cream’), a moisture loving grass, thrives in this wetter section. Further up the slope it is extremely dry. The soil is thinly layered over fill and the drainage is very sharp. Even watering by hand is difficult because the water runs off. A number of plants such as daylilies, hyssop and catmint do grow there but the area is really in need of some sort of a background plant that complements the flowers and provides texture.

The current candidate for this area is pink muhly grass (Muhlenbergia capillaris) partially because it was on sale. The seed heads of this grass are actually pink and even in the pot it is a striking specimen. It supposedly grows up to three feet tall making it one of the shorter ornamental grasses. It has a spread of three feet.

Muhly grass grows under dry conditions but in poor soil it will probably not make maximum growth. This is not a bad thing as some of the more robust grasses become difficult to control where they are too comfortable. Muhly grass supposedly grows much better where the moisture situation is average and the drainage is good. We have one out of two desirable conditions in this area and hopefully rainfall will be adequate to keep it alive.

The grass is also useful in preventing erosion and is adapted to city conditions, having a high tolerance to salt both from de-icing compounds and fertilizers. It is often used on golf courses and center plantings along highways. According to all accounts this is one tough grass that might be up to the challenge of filling in an area where it is difficult to get the kind of coverage needed without creating a monster.

Now for the cons. Like most of the really colorful grasses this one is questionably hardy. (It is a given in gardening that if something is gorgeous it will not grow in your hardiness zone.) Some sources list it as hardy to zone 5 and some suggest it is only hardy to zone 7. Most gardeners discover that hardiness varies by the individual plant. Where one specimen of a plant will survive through the winter another will not. The fern leafed bleeding heart that Pat has generously shared having acquired it from Sharon is fully hardy in this area, while the ones I bought repeatedly succumbed to our winters. All things are not equal in the plant world so we can hope that this is one of the hardier specimens of muhly grass.

The muhly grass is being planted on a southern slope. This is a plus in the plant world. The southern slope is subject to more solar radiation and therefore is warmer than other areas. This can be a plus in plants that are marginally hardy in a given area. It is not necessarily great for plants that are fully hardy and need to have the ground frozen hard all winter.
Which brings us to fall planting and a digression that is marginally relevant to the subject but is a factor in the survival of the grasses. Many gardeners are great advocates of fall planting. Perhaps that statement should be amended to those who write about gardening are great advocates of fall planting. I’ve found very few gardeners in zone 5 who preferentially plant at that time of the year despite the fact that they get great bargains on plants.

Fall planting does have its advantages. The soil isn’t water logged as it is in the spring so planting is easier. The plant isn’t subjected to heat stress as it would be in the summer and watering is rarely needed in the fall. The soil is warmer than the air so the root systems will continue to grow long after the plant appears to have gone dormant. Roots will grow until the ground freezes. It sounds great but unfortunately it doesn’t always work.
Why some plant fail to thrive when planted in the fall is a mystery but we can make some educated guesses. The roots may fail to grow and the plant goes into winter without a good root system. When we clean out our gardens in the fall we often find annuals that have the same little ball of roots in in the shape of the pot that they had when they were planted. The roots have failed to spread into the surrounding soil and it isn’t always because we have failed to loosen them. They just seem to find the new soil a hostile environment. This may happen with fall planted perennial especially if they are put in very late and the soil is colder than they like.

The plants that we buy in the fall may have been in the pot for a considerable amount of time and are stressed beyond recovery. Once the foliage dies back the plant must depend on stored energy to continue to produce roots. This is something that fall planted bulb do as a matter of course using energy stored in the bulb to make a good root system. Stressed plants have little to work with and may not produce healthy roots.

Finally, they may simply not be able to adjust to the new environment is the short time before winter. I fear that this may be the case with my new grass as I probably didn’t get it planted the minimum 6 weeks before the first frost. It is vital to plant in a timely manner.
I have great hopes for this pretty pink grass. If it doesn’t survive the winter we will have learned by experience at a price that was not too great.