<em>Pennisetum</em>, buying guide

Choose by flowering period

Long silky spikelets 8 to 40 cm long stand aloft in summer or autumn, from June to December, depending on species and variety. Among earliest Pennisetum, Pennisetum massaicum ‘Red Button’ offers a charming, dark-red flowering, earlier than that of usual varieties. Pennisetum incomptum is also attractive from early summer thanks to its early flowering.

By contrast, Pennisetum alopecuroides ‘National Arboretum’ is a late-flowering variety that does not skimp on impact. With its purple-violet bottlebrush spikes, it brings grace to borders from late summer through October–November.

Pennisetum massaicum ‘Red Button’ on left, and Pennisetum alopecuroides ‘National Arboretum’ on right

Choose by hardiness

Perennial and hardy under most of our climates, some species of Pennisetum prove more tender and are grown as annuals in cool climate. Pennisetum alopecuroides and their cultivars are the hardiest, enduring without flinching down to -25 °C in very well-drained soil.

Pennisetum villosum and Pennisetum thunbergii display lower hardiness (-5, up to -10 °C in very well-drained soil), they are most often grown as annuals in cold regions. They are species well suited to mild climates and to relatively dry summers.

Among the most tender, Pennisetum setaceum cannot tolerate below-freezing temperatures, so it is grown as an annual in flowering pots or in rockery.

Pennisetum villosum on left, and Pennisetum setaceum ‘Rubrum’ on right

Choose by spike colour

These fluffy bottlebrushes display a variety of shapes and colours. Their flowering is all about subtlety, without garish tones. With spikes often showing muted, bistre or silvery hues, a few skilfully placed clumps of Pennisetum temper bright colours in vivid summer compositions. Creamy white with brownish reflections in Pennisetum alopecuroïdes ‘Hameln’, silvery white in Pennisetum orientale ‘Tall Tails’, brown-black in ‘Black Beauty’ and ‘Moudry’, brown with a grey sheen in Pennisetum alopecuroides f. viridescens, pinkish-beige in ‘Karley Rose’, they are red-purple in Pennisetum setaceum ‘Rubrum’ and Pennisetum thunbergii.

Spikelets sometimes show an unusual aspect for the genus, less cylindrical and more tapered (Pennisetum macourum) or sometimes topped by a tuft (Pennisetum alopecuroides ‘Japonicum’, ‘Magic’).

Colours will be more or less intense according to sun exposure. In all, silky bottlebrushes mature into often blonder shades.

From top left to bottom right: Pennisetum alopecuroides ‘Hameln’, Pennisetum ‘Moudry’, Pennisetum alopecuroides viridescens, and Pennisetum setaceum ‘Rubrum’

Choose by foliage colour

Deciduous or evergreen foliage in warm regions forms a fountain of ribbon-like leaves that remain visually striking even in winter. There is little colour range in their foliage: most Pennisetum bear green leaves, yet they offer a wide palette of shades. A whole series of very luminous cultivars exists. They allow a multitude of combinations with other perennials and grasses. Foliage is often marcescent, drying yet persisting through winter, taking on a lovely straw-yellow or brilliant red and orange hues in autumn.

Greens

Le Pennisetum alocuperoides ‘Hameln Gold’ is a very pretty variety with very fine, lemon to golden foliage that does not scorch in sun. Yellow tone of foliage intensifies with arrival of autumn, colouring orange in sun. It brings plenty of luminosity to sunny beds, fitting contemporary or wild-style gardens.

The Pennisetum orientale ‘Fairy Tails’ forms a handsome clump of supple leaves of a slightly greyish green, topped by very attractive inflorescences in very pale pink with silvery reflections.

Le Pennisetum alopecuroides ‘Cassian’ is a compact variety remarkably luminous in low-angle sunlight. Attractive from spring to autumn, it forms a pretty fountain of very fine foliage, a beautiful green in spring that develops lovely autumn colours, turning vivid red and orange.

The Pennisetum massaicum ‘Red Button’ is a modest-sized variety forming a clump of foliage of a very fresh, clear and bright green. Floriferous culms tinged with purple emerge from this vegetation in harmonious tones with the reddish-purple flowering.

Pennisetum ‘Halmen Gold’ and Pennisetum orientale ‘Fairy Tails’

Purples

Foliage of Pennisetum setaceum ‘Rubrum’ is entirely coloured purplish-red to chocolate. Intensity of colouring depends on exposure: in sun leaves may appear almost black, in semi-shade a rich purplish-red. It is an annual variety, notable for an aspect both exotic and elegant.

Pennisetum setaceum ‘Rubrum’

Choose according to intended use

Essential and versatile, pennisetum can be planted in a rockery, a bed, along a path, or in flowering containers. Some species can also be used as groundcover or to stabilise a dry bank. Quick overview of possible uses!

On a bank

Pennisetum are mainly cespitose grasses, meaning they expand to form dense, compact tufts without ever becoming invasive. But some, few in number, spread from a running stump and can be used as groundcover. A useful asset in a large natural garden or in a meadow. Opt for Pennisetum incomptum, a vigorous species ideal for landscaping difficult areas, for stabilising a dry bank for example. At 1.20 m tall, it will rapidly colonise large open spaces and natural areas with its erect habit.

In large beds

At 1.80 m tall, Pennisetum macrourum is one of the tallest of the genus. Highly architectural, it is perfect for large spaces and for harmonising large sunny beds when paired with large perennials in our milder regions, as it likes heat. It is therefore hard to maintain as a perennial in northern France.

In a mixed border

If you want to highlight a specific area, choose varieties that remain well behaved in place, gradually filling out and easy to slip into annual and perennial beds or into a border.

Pennisetum add movement and naturally structure a composition, even in the smallest gardens. Choose varieties such as ‘Goldstrich’ which retain a medium size (50 to 80 cm in height) and which will, over time, form supple, upright tufts. They will frame many perennials without ever outshining their neighbours.

Pennisetum incomptum, Pennisetum macrourum, and Pennisetum alopecuroides ‘Goldstrich’

In containers

One of Pennisetum’s great qualities is that they adapt easily to cultivation in tubs or window boxes, on a terrace, a balcony or a small urban garden. Provided you choose non-running varieties that are easy to contain. Place pots slightly elevated, suspended for example, to enjoy the attractive effect of their slightly arching foliage.

Among varieties particularly elegant in containers, Pennisetum alopecuroides ‘Little Bunny’ is a dwarf cultivar 20 to 30 cm in height and width. It is a delicate little variety with silky beige-pink spikelets and supple, slightly arching culms.

The clumps coloured from purple-red to chocolate of Pennisetum setaceum ‘Rubrum’, the best-known of the annual pennisetums, will suit an exotic-inspired but ephemeral display perfectly.

You can also combine several small cultivars (Pennisetum orientale) in a large container to create compositions remarkable for their elegance and airy grace.

With its acid-green foliage, Pennisetum alocuperoides ‘Hameln Gold’ brings a bright, highly graphic touch to containers.

→ Read also: Pennisetum: best varieties for pots.

Pennisetum ‘Hameln Gold’

Choose according to ease of cultivation

Pennisetum is a robust grass in most regions. Although your choice depends on aesthetic criteria, make sure the chosen variety is easy to grow. Indeed, in mild climates all Pennisetum grow without difficulty, whereas in harsher climates we recommend choosing a very hardy species, otherwise you may not be able to keep it as a perennial. Pennisetum alopecuroides are most widespread in our gardens; they are also the hardiest and the only ones to tolerate the widest range of growing conditions. They are versatile and will tolerate almost all types of soil, except waterlogged ground that suffocates the roots. In a small space, beware also of species that are difficult to contain, such as the Pennisetum incomptum, which is running.

Pennisetum alopecuroides (Photo: Allan Hack)

Find out more

Discover everything you need to know about this beautiful, popular ornamental grass: “Pennisetum, Bottlebrush herb: Planting, pruning, maintenance” and some ideas for combining them with Pennisetum!

Visit our online nursery to choose Pennisetum species and varieties perfect for your garden or terrace!