Which grasses to choose for acidic soil?

What are the characteristics and benefits of an acidic soil?

A soil is considered acidic when its pH is below 7, often between 5 and 6 for the most common soils. This acidity is mainly due to natural factors, such as the decomposition of organic matter, mineral leaching, the presence of parent rock like granite, or the application of certain chemical fertilisers. Gardeners tend to dislike this type of soil, as microbial activity is relatively reduced. Similarly, deficiencies are frequent.

However, an acidic soil is not always poor soil. For instance, humus-rich soils are generally acidic. Moreover, an acidic soil benefits from natural drainage due to its lightness. It can also be well-supplied with certain micronutrients, such as iron.

So, make the best of a bad situation. True, your soil is acidic, but it can be an advantage if you choose plants that thrive naturally in it. And some grasses particularly enjoy it.

Ten Beautiful Grasses Suitable for Acidic Soils

Grasses are herbaceous plants that adapt equally well to nutrient-rich and nutrient-poor soils. This is why some of them, often thriving naturally in heathlands and wooded areas, will particularly enjoy acidic soil. We have selected for you the ten most interesting grasses.

Japanese Forest Grass (Hakonechloa macra)

In its natural habitat, Japanese Forest Grass (Hakonechloa macra) grows on the edges of woodlands, on semi-shaded slopes with cool, humus-rich soil. This is why it adapts quite well to acidic soil. Over time, it forms beautiful clumps of lance-shaped, lush foliage that cascades in overlapping layers. Hakonechloa macra also produces thin, long-lasting flower spikes that persist through winter. With numerous cultivars available, Japanese Forest Grass offers a wide range of colourful foliage, from green to golden yellow (‘All Gold’), orange and bronze-yellow (‘Nicolas’), mahogany-red (‘Naomi’) to deep burgundy (‘Mulled Wine’) by the end of the season.

Japanese Forest Grass thrives equally well in shade, partial shade, or full sun (provided the soil remains cool).

Japanese Forest Grass

Purple Moor Grass (Molinia caerulea)

Purple Moor Grass (Molinia caerulea) is a native grass originating from acidic heathlands exposed to strong winds. Needless to say, it is perfectly suited to acidic soil. This grass forms dense, attractive clumps of foliage, relatively inconspicuous in summer. In autumn, its foliage turns stunning golden-yellow to orange hues. The tallest varieties, such as ‘Fontäne’ or ‘Skyracer’, are impressive, while the more compact varieties are best planted en masse.

Purple Moor Grass through the seasons

Common Reed (Phragmites australis)

Common Reed (Phragmites australis) is a tall grass with thick, rigid stems and leaves. These upright stems, adorned with leaves, can be variegated with gold (‘Variegatus’) for added ornamental appeal. Common Reed produces purple inflorescences in August, which turn silvery in autumn. This grass thrives in wet conditions. Due to its invasive nature, it is best avoided in small spaces.

Purple Sugar Cane (Saccharum officinarum violaceum)

Purple Sugar Cane (Saccharum officinarum violaceum) is a tall grass that can reach 2.50 m in height and 2 m in width. Suited only to mild climates (it is frost-sensitive below -5°C), this grass boasts beautiful ribbon-like, narrow, arching foliage borne on massive stems. Its deciduous foliage emerges deep purple before turning dark green, tinged with purple and red.

Greater Wood-rush (Luzula sylvatica)

Greater Wood-rush (Luzula sylvatica) is a grass belonging to the rush family (Juncaceae). It forms a clump wider than tall, composed of stiff, hairless, smooth, and glossy leaves with non-sharp edges. It produces loose, lightly coloured spikes between June and August, which add ornamental interest, especially when planted in groups. Varieties with golden foliage (‘Solar Flare’) or variegated foliage (‘Marginata’) bring light to shaded areas. This grass is ideal as ground cover or for borders.

Greater Wood-rush

Rushes (Juncus)

Rushes (Juncus) are herbaceous plants that thrive in wet or even aquatic environments. They are often planted along streams or ponds, where they spread via rhizomes. Rushes form clumps of tall, leafless stems that are very straight and flexible. Some varieties, such as Corkscrew Rush (Juncus effusus ‘Spiralis’), are highly original with their twisted stems. Rushes flower in reddish-brown spikes.

Wavy Hair Grass (Deschampsia flexuosa)

Wavy Hair Grass (Deschampsia flexuosa) forms a dense, low clump of evergreen, fine green foliage. From June to August, the foliage is literally hidden beneath a profusion of slender stems topped with very delicate, golden-beige inflorescences tinged with bronze, creating a mist-like effect. This grass self-seeds easily and thrives in all exposures. It is a “well-behaved” grass that evokes a wild meadow.

Wavy Hair Grass

Wood Sedge (Carex sylvatica) and Pendulous Sedge (Carex pendula)

Wood Sedge (Carex sylvatica) and Pendulous Sedge (Carex pendula) are two graceful and vigorous grasses perfectly suited to acidic soils. Wood Sedge forms a tufted clump of bright green, linear leaves. Pendulous Sedge grows into a large clump of evergreen, broad, arching leaves. Both produce slender, tall flowering stems of great elegance, consisting of a terminal spike of male flowers and two to three female spikes.

Wood Sedge and Pendulous Sedge

Sheep’s Fescue (Festuca ovina)

Sheep’s Fescue (Festuca ovina) is a compact, upright, and highly resilient grass. It forms a small clump of fine, bluish-green foliage that turns straw-yellow in winter. Its inflorescences emerge as green spikes that turn purplish. It adapts to all soil types, including acidic soils, and is ideal for borders, rockeries, or flower beds.

How to plant and care for these acid-loving ornamental grasses?

Once you’ve chosen the most suitable grasses for acidic soils, it’s time to plant them. Although undemanding, these grasses will grow more vigorously in well-prepared soil. Moreover, their establishment will be much easier.

In acidic soil, adding compost or organic matter helps balance the pH and enrich the soil with nutrients. It’s also essential to remove weeds that could compete with young grasses. Finally, a little sand or gravel should be added to the bottom of the planting hole to improve drainage. Once your grasses are planted and watered generously, apply an organic mulch such as wood chips, dead leaves, or pine needles to retain soil moisture and suppress weeds.

In terms of maintenance, grasses remain just as undemanding as during planting. Water them regularly in the weeks after planting, and then during periods of intense heat or drought. It’s also necessary to remove dry stems at the end of winter to encourage fresh growth in spring.

How to combine grasses in acidic soil?

Pairing grasses with other plants suited to acidic soils creates harmonious scenes, rich in textures, colours, and shapes. However, for perfect success, it’s essential to choose acid-loving plants or at least those tolerant of acidic soils. Among perennials, consider astilbes, tiarellas and heucherellas, or hostas to add striking contrasts.

Among shrubs, heathers form consistently successful pairings with grasses. You can also plant these grasses alongside rhododendrons and azaleas, as well as with an Hydrangea macrophylla.

In acidic soil, rushes can be paired with heathers, astilbes, and tiarellas

Ferns from the Dryopteris or Athyrium genera and creeping wintergreen (Gaultheria procumbens) blend beautifully with woodrush for their ground-covering effect. Finally, in spring, bulbs such as daffodils, crocuses, and camassias add a lovely splash of colour before the grasses regrow.