Corsican mint is the smallest and most intensely fragrant of all mints: a moss-like ground cover barely an inch tall that releases a strong pennyroyal-peppermint scent when stepped on. Tiny lilac flowers dot it in summer. It belongs between stepping stones, in a rock garden, or at the edge of a container where the mat can spill over.
Unlike most mints it prefers part shade and steady moisture, and it scorches in hot afternoon sun. Plant plugs 6 inches apart in rich, moist soil and it knits into a mat in a season; it spreads by surface runners rather than deep rhizomes, so it is far easier to keep in bounds than its larger cousins. It takes light foot traffic but not the wear creeping thyme can take.
It is hardy to zone 6 and can be lost in a hard winter without snow cover; a light layer of pine straw sees it through, and a pot of it on a windowsill is cheap insurance. The leaves are the flavouring in crème de menthe, and a few sprigs go a long way in a drink or a fruit salad. Deer leave it alone.
Rust
Orange to brown raised pustules on the undersides of leaves, with yellow spotting on the upper surface. Heavy infections cause leaves to yellow and drop.
Remove and destroy infected leaves. Avoid overhead watering and improve air circulation. Apply a sulfur or copper-based fungicide if it spreads. Clear plant debris in fall.
Powdery mildew
White or grey powdery coating on leaves - usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.
Grey Field Slug
Deroceras reticulatum →Large irregular holes chewed in leaves, with slime trails on foliage and soil.
Hand-pick at night, set beer traps, or apply iron phosphate bait. Remove debris and mulch where they hide.