When speaking of the Poaceae family, there is a lot of back-and-forth among gardening enthusiasts.
Some consider grass to be a weed, some feel there’s nothing better than a well-manicured lawn, and there are some that feel both sides have their points.
Ornamental grasses such as Muhlenbergia capillaris (mew-len-BERG-gee-uh kap-ill-AIR-iss) really help the argument for this middle road.
While native to the eastern portion of North America, it can be found throughout much of the US.
This perennial plant is known by a whole host of names, most notably:
- Cotton candy grass
- Hairawn muhly
- Pink hair
- Pink muhly grass
Hairawn Muhly Care
Size and Growth
One of the main attractions of this ornamental grass is its more compact size, with mature clumps only reaching around 3’ feet tall and wide without blooms.
However, it can reach about 4′ feet tall and 3′ feet wide as it matures in bloom.
The pink muhly grass commonly has deep dark green foliage during the spring and early summer.
It will generally grow at a rate of 1’ foot per year and has narrow, tapered green leaves.
Flowering and Fragrance
Of course, the biggest draw comes in late summer to fall, when the grass bears plumes of tiny pink to reddish-pink fuzzy flowers.
Those who see these slender plumes moving in the wind often compare the blooms to cotton candy.
The show can last between 4 and 8 weeks before the flowers lose their color, although they remain an attraction long after.
Note that when growing from seed, pink muhly grass plant won’t bloom for the first year as it doesn’t mature until the second year.
There are also a number of cultivars and hybrids which boast variations in their bloom color, such as:
- ‘Pink Flamingo’ – hybrid plant crossed with Muhlenbergia lindheimer that bears slender leaves and bright pink blooms
- ‘Regal Mist’ – reddish pink flowers
- ‘Rose Muhly’ – shorter cultivar with reddish-pink blooms
- ‘Undaunted® Ruby’ – reddish, feathery arched blooms
- ‘White Cloud’ – cream-colored upright blooms
Light and Temperature
Proper lighting is important to any plant, although it can be easy to forget with grasses.
Hairawn muhly is a good example of how the amount of light affects plants.
It can tolerate partial shade conditions but will not reach full size, and the blooms will suffer.
For the best results, the plant requires full sun – even when grown in a container.
Too much shade will weaken the stems, so you must ensure it gets a bare minimum of 4 hours of full sunlight per day.
At least 6 to 7 hours of full sun is recommended for the best results, which can be in the morning or evening if you’re growing in a particularly arid region where the midday sun may be too harsh.
This grass loves dry heat, so it doesn’t fare too well outdoors in humid locations such as along the Gulf.
Indoors, it can handle average household humidity without any issue, preferring 20% percent or lower, but capable of handling up to 40% percent humidity before the risk of fungal infections or rot become noticeably higher.
You’ll often find pink muhly grass benignly grown outdoors in USDA hardiness zones 6 to 9, although there has been some success in zone 5.
The plant will die back as temperatures drop later in the fall, and they’re generally cold tolerant.
However, if the temperature drops below 10° degrees Fahrenheit, the roots will be affected, and the plant can die.
Watering and Feeding
Young plants will need more water until they’re established, and you will want to ensure the top of the soil is always slightly moist.
However, once established, pink muhly grass has good drought tolerance.
Expect some inconsistency with blooms during extreme droughts, and while it hates to be waterlogged, the plant is known to survive a touch of flooding from heavy rains as long as the soil doesn’t stay soggy for long, and it’s not currently dormant.
For mature plants, you will only need to water when the soil is dry 2” inches down. You can test this by sticking your finger straight down in the soil to the second knuckle.
If it’s dry at your fingertip, it’s time to water.
The bottom-up method is perfect for potted hairawn muhly, but you can also use the soak-and-dry method on both potted and planted specimens for great results.
As fungal infections are a problem with this plant, be sure to avoid getting the foliage wet as much as possible, so there’s less chance of getting moisture trapped between the leaves.
If you’re wondering what kind of fertilizer you will need to buy this time, you can relax.In fact, there’s a good chance you won’t have to fertilize this grass at all!
If it doesn’t look like it’s growing quite right, you can add a little balanced, water-soluble fertilizer to the soil in spring to give it a boost.
Another popular trick is to add a thin layer of organic compost over the ground in early spring, just to give the plant a tiny boost.
Something else that may sound counterintuitive is that cotton candy grass is sensitive to excess nitrogen.
Nitrogen is normally important for grasses, since it gives a huge boost to stem and foliage growth.
However, this particular species will actually result in weaker, thinner stems and scraggly growth.
Soil and Transplanting
“If you have soil, it will grow” seems to be a catchphrase to keep in mind for this plant.
Pink muhly grass can grow in just about any soil type as long as it’s well-drained soil. However, it can also tolerate a variety of soil conditions, including poor soils and dry soils, once established.
It prefers sandy or even rocky soil, so if you’re dealing with heavy clay soil, try mixing in an aggregate at 2 parts soil to 1 part aggregate.
Some popular aggregates include coarse sand (AKA builder’s sand), pea gravel perlite, and vermiculite.
You can also use orchid bark or coconut coir in a pinch, even though they’re technically amendments and not aggregates.
If growing your pink muhly grass in a container, any standard potting soil will work fine. The only consideration you’ll need beyond the drainage is the soil pH.
Cotton candy grass will be fine in most gardens and prefers a slightly acidic 6.1 to neutral 7.0.
It doesn’t fare well in neutral soils above 7.0, although home growers have mentioned success in moderately acidic soils as low as 5.6.
Remember that you should keep the soil moist and always check the soil moisture often during the first few after planting. Adjusting the irrigation time is also necessary.
You generally won’t have to uproot this ornamental grass in the garden, but if you plan to grow it in a container, pick a pot at least 12” inches deep.
You will need to repot the plant every 2 to 3 years to replace the potting soil and possibly divide it into smaller clumps.
Grooming and Maintenance
One of the things people love about hairawn muhly is the fact that it pretty much takes care of itself.
In late winter, cut back the old growth, so it’s about 3 to 4” inches above ground level.
You may need to check occasionally to ensure a little breathing room between clumps so moisture doesn’t become trapped.
It’s also a good idea to weed regularly, but this won’t be a problem if you like to mulch your garden.
How To Propagate Pink Muhly Grass
Propagating this plant is easy, especially from seeds.
However, despite the abundance of seeds, it doesn’t commonly self-seed, meaning you can leave the spent flowers for the birds without risking new pink muhly grass taking over your garden the next year.
You can also propagate through division, which is generally more popular with plants grown in containers.
Cotton Candy Grass Pests Or Diseases
You aren’t going to find many plants as hardy as this one!
Unless it’s been waterlogged, you’ll be able to enjoy a plant that’s generally free of pests and disease, deer resistant, and can tolerate drought, frost, heat, pollution, salt, and even wind.
Rabbits won’t snack on it, but they may use it for shelter.
Lacewings sometimes hang around the plant but won’t feed on it, and ladybugs are attracted to the plant, making it a great way to enlist the help of this natural predator for your garden.
There’s some anecdotal evidence that aphids may attack the plant but no documented proof.
Almost every instance of disease can be linked directly to excess moisture.
Fungal root rot, rust, and tar spot are the three most common fungal diseases, with rust being the rarest of the three.
One final benefit of this plant is that it’s not known to be toxic to humans or pets. It’s also safe around horses and livestock.
Muhlenbergia Capillaris Uses
Perfect for borders, landscaping, and all sorts of municipal projects such as medians and even golf courses, there aren’t many spots pink muhly grass won’t fit in.
Even better, its root system helps prevent soil erosion, making it a great choice for steep banks.
This perennial grass is also useful in cottage gardens and mass plantings with its pink plumes, making it an attractive addition. It also works well as a wildlife cover for nests and shelter for native birds.
Because they’re late bloomers, this ornamental grass makes wonderful companions for many other plants, such as aster, bee balm, black-eyed Susan, and sneezeweed.