Mentha longifolia

RHS Plant Profile

horse mint

Other common names

brook mint, long-leaved mint, water mint

Synonyms

Mentha sylvestris L.

Herbaceous Perennial

Buy this from Plant Nurseries
10 Suppliers

A spreading perennial, to 1.2m, with hairy, green to grey-green leaves with a musty, minty smell. Branched, tapering spires of tiny, pale purple or white flowers are produced in mid- to late summer

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

1-1.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 1-1.5 metres
Max Height: 1-1.5 metres

Growing Conditions

Chalk Clay Loam Sand

Moisture: Moist but well–drained or Poorly–drained
pH: Acid or Alkaline or Neutral

Position

Full sun Partial shade

Aspect: North–facing or West–facing or South–facing or East–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H7

Colour & Scent

Fragrance Foliage

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Lamiaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Suckering
Genus: Mentha are aromatic, rhizomatous perennials with opposite, toothed leaves and small tubular flowers in spikes of whorls in summer
Name Status: Correct
Plant Range: Europe, N Africa, SW Asia

How to Grow

Cultivation

Grow in moist but well drained soil in full or partial sun. May have to potential to become a nuisance; restrict the root run in a deep container and plunge into the ground, or plant in a well chosen site where it can grow unrestricted. See mint cultivation for more information

Propagation

Propagate by seed or division in spring or autumn

Suggested planting locations and garden types

Cottage and informal garden
Wildlife gardens

Pruning

Cut back after flowering

Pests

May be susceptible to caterpillars, cuckoo spit (froghoppers) and mint beetle

Diseases

May be susceptible to powdery mildews and mint rust