Plant problems

Why Are My Phalaris Leaves Curling?

Q: Should I cut back phalaris arundinacea Picta in summer?

Yes; cutting Phalaris arundinacea 'Picta' (gardener's garters) back hard to ground level in midsummer (typically late June to July, when the first flush of spring growth has lost its fresh appearance and the leaves are beginning to tatter, curl, or show tip scorch) is the standard and strongly recommended cultural practice for this grass in UK gardens. The hard midsummer cut-back to the base stimulates a vigorous flush of new growth from the base of the plant, producing a fresh crop of bright, cleanly white-and-green striped leaves in late summer and autumn (August to October) that are significantly more attractive than the tattered, curled, scorched foliage of an uncut plant at the same time of year. The new growth produced after the midsummer cut-back is typically fresher, more vividly variegated, and less prone to curling and scorching than the first flush of spring growth, particularly in a dry or warm UK summer. Cutting back: use garden shears, a hedge trimmer, or secateurs to cut the entire clump back to within 5 to 10 cm of the ground (or to ground level if desired); the cut is hard but the plant is extremely vigorous and will produce new leaves within two to three weeks of the cut even in warm, dry conditions. After cutting back, water thoroughly if the soil is dry to encourage the new growth to develop quickly. A second light cut-back in autumn (October) may be needed to tidy the new growth before winter, but is not usually necessary; the new growth from the midsummer cut-back remains fairly fresh through September and October in most UK conditions.

Q: Is phalaris arundinacea invasive in the UK?

Phalaris arundinacea (reed canary grass) is a native UK species, native throughout England, Wales, Scotland, and Ireland in wet, damp, and waterside habitats, and as such is not classified as an invasive non-native species in the UK context. The ornamental variegated cultivar Phalaris arundinacea 'Picta' (gardener's garters) is a cultivar of this native species and is therefore also not classified as invasive under UK law. However, both the wild type and the ornamental cultivar are vigorous spreaders in suitable conditions; the wild type (Phalaris arundinacea) is capable of forming extensive, dense monocultures on wet riverbanks, ditch margins, and wet meadows in the UK, sometimes displacing native wetland plant communities; it is considered ecologically dominant or problematic in some UK wetland contexts where it outcompetes more diverse native wetland vegetation. In a dry garden context, phalaris 'Picta' spreads by underground rhizomes and can gradually colonise a border or bed, spreading into adjacent areas and proving difficult to eradicate; the rhizomes can spread several metres in a season in fertile, moist conditions. In a small garden, containing phalaris 'Picta' with a root barrier or growing it in a large container sunk into the ground (with the bottom removed) is the most practical approach to prevent invasive spread while still enjoying the attractive variegated foliage. In a larger, informal, or naturalistic garden, or in a wet or damp area where its spread can be accommodated, phalaris 'Picta' is a highly effective ground-cover grass that provides vivid white-and-green variegated foliage from spring to autumn.

Q: What are the best conditions for phalaris arundinacea Picta in a UK garden?

Phalaris arundinacea 'Picta' (gardener's garters, ribbon grass) grows best in UK gardens in the following conditions: Moisture: consistently moist to wet soil is preferred; the plant performs best beside ponds, in bog gardens, and in damp, humus-rich borders; it tolerates periodic flooding; however, it also grows acceptably in ordinary garden borders if watered regularly, and is more drought-tolerant once established than its waterside-native origins might suggest. Light: full sun to partial shade; in full sun with adequate moisture the variegation is bright and vivid; in dry, full-sun conditions the white-striped portions scorch; in light to moderate shade the variegation remains attractive and the plant is less likely to scorch; in deep shade the growth is weaker and more prone to tattering. Soil: fertile, moist to wet, neutral to slightly acidic; tolerates a wide range of soil types including heavy clay (which it prefers when wet) and loam; less good on very freely draining sandy or chalk soils without irrigation. Position: waterside, bog garden, or damp, informal border areas work best; avoid very formal, dry, or free-draining borders where containment and irrigation are difficult. Management: cut back hard to ground level in late June or July when the spring foliage begins to tatter; this is the single most important maintenance action and produces a fresh, attractive second flush of foliage in late summer and autumn; contain the spreading rhizomes with a root barrier if growing in a small formal border. Container: grows well in a large container (minimum 40 cm diameter) standing in a saucer of water; the saucer constrains the roots and provides consistent moisture; replace the compost every two to three years.

Phalaris arundinacea 'Picta' (gardener's garters) is one of the most widely grown variegated ornamental grasses in UK gardens, producing bright white-and-green striped, broad, strap-like leaves from spring through autumn. The white-striped leaves curl and scorch from drought, too much sun in a dry position, or natural midsummer tattering. A hard cut-back to ground level in late June or July is the key annual maintenance that restores fresh variegated foliage for late summer and autumn.

Drought and dry soil

Phalaris is native to riverbanks, wet meadows, and marshy ground; in a dry garden border without adequate irrigation, the white-striped leaves curl inward from the margins, scorch at the tips, and may roll entirely in extended dry spells. The white variegated portions are more susceptible to drought scorch than the green portions, giving a distinctive burned white-margin appearance in drought conditions. The plant is more drought-tolerant once established than its waterside origins suggest, but consistent moisture gives the best results.

What to do

Water regularly in dry spells; in hot summers, water deeply two to three times per week in a border setting. Mulch the base to retain soil moisture. In a bog garden or pond margin, the consistent moisture prevents drought curl entirely. In a dry summer, the midsummer cut-back (described below) refreshes the foliage more effectively than irrigation of tattered leaves; cut back first, then water well to support the new flush of growth.

Too much sun in a dry position

The white portions of the variegated leaf lack chlorophyll protection against excessive light; in a very hot, exposed, dry full-sun position in a UK summer, the white-striped areas scorch and the leaves curl at the margins. In the same conditions with adequate moisture, the plant performs acceptably in full sun; it is the combination of full sun and dry soil that causes most scorching. In partial shade with adequate moisture, the plant rarely scorches and the variegation remains attractive through summer.

What to do

In a hot, full-sun border, either ensure consistent irrigation to prevent drought scorch, or grow in a position with afternoon shade (which reduces peak leaf temperature without reducing the overall growing conditions significantly). Dappled shade beside a pond or stream with consistent moisture is an ideal position that prevents both drought and sun scorch. In a container, move to a lightly shaded position during the hottest weeks of summer if the foliage is scorching.

Summer tattering and semi-dormancy

Phalaris 'Picta' commonly loses the fresh appearance of its spring variegation by midsummer regardless of growing conditions; the leaves curl, tatter, and the tips scorch or brown, particularly from July onwards. This is a natural characteristic of the species and is not purely a cultural failing. The recommended response is a hard cut-back to ground level in late June or July, which stimulates a fresh flush of brightly variegated new leaves in late summer and autumn.

What to do

Cut the entire clump back to within 5 to 10 cm of ground level using garden shears or a hedge trimmer in late June to July when the foliage begins to tatter. Water thoroughly after cutting to encourage the new flush of growth. Fresh new leaves develop within two to three weeks and remain bright and fresh through August to October. This single cut-back is the most effective way to maintain the attractive appearance of phalaris 'Picta' through the growing season; an uncut plant looks increasingly tatty from July onwards.

Frequently asked questions

Why are my phalaris leaves curling?

Phalaris leaves curl most commonly because of drought and dry soil (native to wet, damp ground; white-striped leaves curl inward and scorch from the tips; water deeply and regularly in dry spells; mulch to retain moisture; midsummer cut-back refreshes foliage more effectively than irrigating tattered leaves), too much sun in a dry position (white portions lack chlorophyll protection; scorch in hot, dry full-sun; provide afternoon shade or consistent moisture; dappled shade beside pond or stream is ideal), or summer tattering and semi-dormancy (natural characteristic regardless of conditions; cut back hard to ground level in late June to July; fresh brightly variegated new leaves develop within two to three weeks and remain fresh through October). Midsummer cut-back is the key annual maintenance action.

Should I cut back phalaris arundinacea Picta in summer?

Yes; hard cut-back to ground level (5 to 10 cm) in late June to July, when the first flush of spring growth has lost its freshness, is strongly recommended. Use garden shears, hedge trimmer, or secateurs. Water thoroughly after cutting. Fresh, brightly variegated new leaves develop within two to three weeks and remain attractive through August to October. The new post-cut flush is typically more vividly variegated and less prone to curling and scorching than the first spring flush. A second light tidy in October is optional; usually not necessary. This cut-back is the single most important maintenance action for phalaris 'Picta' in UK gardens.

Is phalaris arundinacea invasive in the UK?

The wild type (Phalaris arundinacea) is a UK native; not classified as invasive under UK law. However, both wild type and 'Picta' cultivar are vigorous rhizomatous spreaders; the wild type can form dense monocultures displacing native wetland vegetation in some UK contexts. In a garden border, 'Picta' spreads vigorously by rhizomes and can colonise adjacent areas and prove difficult to eradicate. In a small garden, contain with a root barrier or grow in a large container sunk into the ground with the bottom removed. In a larger, informal, or damp setting where spread can be accommodated, it is an effective variegated ground-cover grass from spring to autumn.

What are the best conditions for phalaris arundinacea Picta in a UK garden?

Moisture: consistently moist to wet soil preferred; best beside ponds, in bog gardens, and in damp humus-rich borders; tolerates periodic flooding; more drought-tolerant once established than origins suggest. Light: full sun to partial shade; bright variegation in full sun with adequate moisture; scorches in dry full-sun; less likely to scorch in partial shade. Soil: fertile, moist to wet, neutral to slightly acidic; tolerates heavy clay when wet. Management: cut back hard to ground level in late June or July; contain spreading rhizomes with a root barrier in formal borders. Container: grows well in large containers standing in a saucer of water; replace compost every two to three years.