For those seeking to beautify compact spaces with striking autumnal features, consider turning your attention to ornamental grasses. Particularly commendable is the distinguished Hakonechloa macra – a perennial, herbaceous grass that thrives in the shade. This plant’s soft foliage slowly turns from green to varying hues of red, creating a stunning visual spectacle, especially when combined with ferns, irises, hostas, and hellebores.
An additional choice, providing year-round visual appeal, is Carex morrowii ‘Irish Green’. This evergreen, perennial grass is clump-forming and best cultivated in shaded areas.
For those with a semi-wild spot on offer, filled with warm, sunlit, well-draining soil, Briza maxima could be the perfect fit. This robust annual species comes with the added benefit of frequent self-seeding. It boasts delicate, trembling clusters of flowers, subtly changing from a pale violet-green to a glimmery silver-gold hue as the season shifts to autumn.
Ornamental grasses bring more to the table than just their autumnal presence. Their long-lasting flowers are a highlight, subtly brightening any garden design and pairing excellently with late-blooming perennials such as aster, helenium, sanguisorba, persicaria, agapanthus, rudbeckia, dahlia, and helianthus.
In my personal green space, an autumnal delight is the Pennisetum villosum, colloquially known as feathertop. Its soft, silver-grey inflorescences sway slightly in the breeze and glow under the low-lying September sun. As a compact, herbaceous variety, I’ve placed it next to the arresting Euphorbia wulfenii evergreen and vibrant orange Californian poppies by our house entrance. Together, these plants create a captivating contrast of silhouettes and growth patterns, holding one’s interest for many seasons.
As simple as growing from seeds, all pennisetums require ample sunlight, heat, and a lightweight, damp yet well-draining soil in a protected location to truly thrive. If your garden’s terrain is rather dense and prone to moisture retention during winter, consider adding a good amount of horticultural grit or positioning the plant next to a path or wall for naturally improved drainage. An alternative would be to opt for a sun-soaked gravel garden as it delivers the exact soil conditions needed. Splendid choices for your garden in terms of pennisetum varieties include the radiant silver-pink Pennisetum ‘Karley Rose’, Pennisetum ‘Fairy Tails’, the robust, majestic Pennisetum orientale ‘Shogun’, and the Chinese fountain grass, Pennisetum alopecuroides ‘Hameln’. These particular plants boast fluffy, feather duster-esque flowers that come in shades of glossy-creamy-blush-pale rose.
Furthermore, these plants also offer a feast of delightful autumn hues as their leaves transition from green to gold before ultimately shedding down to the ground as winter sets in. If you possess a greenhouse, polytunnel or sunroom where you can provide winter protection, along with the devotion to do so, then the frost-sensitive hybrid Pennisetum x advena ‘Rubrum’ would also make an impressive container plant for the early autumn garden.
Stipa gigantea, a robust and regal golden oats grass, doesn’t need much coddling. This plant is known for its thick clusters of tenacious, year-round greenery, towering over which are elegant clusters of oat-like blooms that emerge in the warmer months. These flowers linger on the plant for several months and slowly change from a rose-gold colour as the seasons shift. With its sunlight-catching, iridescent flower stems, this captivating plant is perfect for sunny borders or pebble gardens, especially when planted amongst a lower plant ensemble. The popularity of Stipa gigantea, which thrives in a diverse range of soils as long as they aren’t too damp, continues to flourish. Personally, I cultivate it in my sunny front garden along with linaria, calaminth, gaura, sanguisorba and perennial geraniums. Although it’s a sizable plant (reaching over 2m in height and 1.2m in width, with the majestic Stipa ‘Golden Fontaene’ variety reaching even greater heights), its open growth pattern lends itself well to smaller gardens.
Surviving in the hardy and majestic miscanthus genus category, but without being an evergreen, is a superb selection of herbaceous species of ornamental grasses. These grasses provide autumn gardens with a vital touch of contrast and sparkle that includes colour and texture. As impressive clump-forming plants, they are not recommended for smaller or wind-exposed gardens as they may become untidy. They rapidly grow, reaching up to 1.8m in height and spread across 1.4m or more, variety depending. Miscanthus sinensis ‘Maelpartus’, with its height, feathery dusty-red blooms which slowly turn to a silver-pink, is one of the classics. Appreciable traits include leaves distinguished by a silver central mid-rib and stunning autumn coloured foliage. Additional outstanding variants worth considering are Miscanthus nepalensis, known for its remarkably enduring tall elegant blooms, and Miscanthus sinensis ‘Graziella’, celebrated for its long-lasting silver-pink blooms and vibrant autumn leaves.
The Calamagrostis brachytricha is a highly valued ornamental grass well known for its tall, airy, durable floral plumes and vibrant autumn leaves. The plant thrives in sunlight as well as dim light. Its flowers, which bloom in summer, remain on the plants well into the fall. Other prominent varieties include Calamagrostis ‘Overdam’ and C ‘Karl Foerster’, both known for their structured, vertical growth pattern and preference for a sunny, well-drained location.
Other decorative grasses offering exceptional autumn interest, particularly suitable for smaller areas, include the regal Hakonechloa macra, a shade-tolerant perennial species. It pairs well with ferns, hostas, hellebores and irises. As autumn nears, its gentle foliage gradually takes on red and crimson hues. The Carex morrowii ‘Irish Green’, a perennial, evergreen, clump-forming variety, provides year-round interest and thrives best in shady areas. If you can accommodate its tendency to self-seed widely in a sunny, free-draining location, Briza maxima, a hardy annual species, is another suitable option. Its delicate pale purple-flourishing flowers fade to silver-gold come autumn.
Another impressive inclusion is the Anemanthele lessoniana or pheasant tail grass. This hardy, sprightly, adaptable, semi-evergreen species copes well under less-than-optimal growing conditions. Its autumn leaves and graceful flower panicles that appear in late summer add to its ornamental appeal. The pheasant tail grass’s distinguishing attributes are its slender leaves, which turn to golden, copper, and scarlet hues in autumn. The grass can grow in both full sun and light shade and in moist soil. Lastly, we have the Molinia caerulea ssp caerulea ‘Heidebraut’, or moor grass, another aesthetically pleasing perennial grass species. It features tall, trembling, violet flower stalks that subtly change to golden tones in autumn.
Ornamental grasses have diverse growth needs, but a shared dislike is being divided or planted anew once autumn begins. They flourish better when cultivated in springtime, rapidly maturing to bring you their exquisite beauty.
This Week’s Gardening Advice
– As the first frost of autumn draws near, ensure that you label the different types of dahlias so you can identify them easily. This is particularly crucial if you’re considering lifting and storing their tubers indoors during the winter.
– Start picking ripening apples manually, noting that select varities are fit for longer storage than a few weeks – these are typically the late-harvest varieties. Any apples which exhibit clear signs of blemishes or cuts on the skin will decay rapidly. Early harvest types can be stored for around four to eight weeks while late-harvest types can mature in storage, lasting a few months when stored in a cool, dark, pest-free, and frost-free area like a disused chest freezer.
Mark Your Calendars
From Friday, October 4th to Sunday, October 6th, Kells Bay Gardens will be hosting the Southern Symposium IX, featuring prominent guest speakers such as Adam Frost, Scott McMahan, Jimi Blake, Derry Watkins, and Raf Lenaerts. Ensure to reserve your spot. More information is available at kellsbay.ie.