Moor Grasses: Fireworks in the Garden

Fall is a wonderful season to talk about ornamental grasses, even if we should talk about them all year round! It is in this spirit that I am making this fall season an ornamental grass “special series”! After having presented to you small grasses and grasses with almost black foliage, I wanted to introduce you to another species less known than the Chinese eulalias (Miscanthussinensis) or the feather reed grass (Calamagrostis spp.), but oh so interesting for sunny gardens. These are the purple moor grass (Molinia spp.).

A Small Select Group

It is quite easy and quick to draw up a general portrait of molinias, because there are only two species, according to Plants of the World Online: Molinia arundinacea and the purple moor grass (Molinia caerulea). And again. There is a little debate as to whether these are not rather two subspecies of the purple moor grass.

In any case, purple moor grasses are naturally present in Europe and the Caucasus.

Most experts confirm that cultivars do not reseed in the garden and this is also my personal observation. Everywhere I have seen ornamental purple moor grasses, I have not noticed any problems. However, it is good to take some precautions with regard to the species (M. caerulea). In its native region, and in particular in humid environments, the plant sometimes presents some challenges. Introduced to the United States and Canada, the plant is under surveillance, in particular in Michigan and Wisconsin.

That being said, focusing on ornamental hybrids, purple moor grasses remain very interesting and useful in the garden.

A Grass for Damper Soils

In their natural habitat in Europe, purple moor grasses grow in marshes, peat bogs and wet meadows. This suggests that molinias would be happier in soils that are watered regularly. Although the plants have good drought resistance, they will suffer from extreme heat waves and long periods without rainfall. They seem to be indifferent to pH, although they do like acidic soils.

In terms of light, they are also plants for full sun, like most true grasses of the Poaceae botanical family. In general, molinias are hardy up to USDA zones 4 to 8.  

Low Foliage

One of the particularities of purple moor grasses is that the foliage develops in a rosette of fairly low leaves. From spring to autumn, this mass evolves, changes color, but always remains just as well structured. It is a plant that develops in a clump. It does not produce invasive rhizomes. We like grasses that stay in their place!

In the fall, the foliage of purple moor grasses, and in particular of the ‘Skyracer’ variety, becomes completely golden with warm tones. It’s a real beauty! It’s also advisable to leave the foliage and flower stems in place for the winter because the tall varieties remain decorative. The only maintenance required for purple moor grasses is to cut back the plants early in the spring, as soon as green begins to appear in the heart of the plant. When the plant becomes bare in its center, you can take advantage of the spring season to divide the plant and replant it.  

Light Blooming

It is well above the foliage that the inflorescence develop. All the flowers form a sort of inverted triangle, that is to say that the flowering often opens towards the sky. This display is composed of magnificent, very airy panicles, which can measure more than 15 cm long, in particular in large varieties.

And that’s what I like about purple moor grasses. There is a semi-transparency created by this light and airy inflorescence. In garden design, we are often interested in shapes. We see plants are cones, balls, upright or weeping shapes. The purple moor grass becomes an interesting addition, precisely because of its more open shape towards the top.

Some Varieties to Discover

Because it is unique in its kind, the ‘Skyracer’ purple moor grass  (Molinia ‘Skyracer’) has been my favorite for several years. It is an imposing plant. The foliage forms a large mass 75 cm (30 inches) high and the flower stems stand higher than two meters (6 feet) above the ground. These famous flower stems are surprisingly wind resistant. This variety makes a good focal point and it’s great for creating a semi-transparent screen effect. ‘Skyracer’ can become the star plant in a flower bed.

Still large in size, but not as imposing, the variety ‘Strahlenquelle’ forms a ball of fine leaves from the center of which the flower stems burst forth, like an explosion. In its shape, it looks like a smaller version of ‘Skyracer’ which peaks at 120 cm (4 feet). And if you’re looking for a medium-sized version of those above, you should turn to ‘Moorflamme’.

Other purple moor grasses are rather medium-sized, with foliage 30 to 60 cm (1 to 2 feet) high and flower stems that rise to about 75 to 90 cm (30 to 35 inches) high. It’s all in the nuances of shapes in this small group. For example, the variety ‘Moorhexe’ has a more upright habit than ‘Dauerstrahl’. The latter has beautiful dark green foliage with flowers that tend towards burgundy red.

Then, as a border plant, the variegated foliage variety, ‘Variegata’ works wonders, with its grooved foliage of cream and chartreuse of a beautiful intensity. This one is much more present in gardens and it behaves very well. Its particular foliage offers beautiful plays of contrasts, shapes and textures with other plants.

So, purple moor-grasses add personality wherever they are planted. They stand out and often act as focal points in flowerbeds. It blends well with many perennials and, of course, with other ornamental grasses. They are just as interesting as isolated plants, in small groups, or in large clumps. In short, purple moor grasses are among my favorite grasses for landscaping, along with switch grass (Panicum spp.), blue stem (Andropogon spp.) and autumn moor grass (Sesleria autumnalis).

This fall, treat yourself to a green firework display with purple moor grasses!