The Adaptations of Spearmint

Moisture-Loving

• Spearmint is adapted to moist soil conditions and spreads continuously until it encounters dry soil. In the arid West, its spread is limited to where irrigation is provided, but in areas with regular summer rainfall and clay soils, spearmint has invasive characteristics. Its penchant for moisture is paralleled by a preference for fertile soil. In nature, riparian zones and wet, low-lying areas are generally characterized by rich topsoil, which adds to the vigor of spearmint when replicated in the garden environment.

Shade-Tolerant

• Spearmint grows well in full sun, as long as moisture is abundant, but is equally well-adapted to shady conditions. In areas with hot summers, its vigor in full sun is curbed by the heat. It will send up its flowers early and look a little ragged for the rest of the year in these climates. In part shade it grows lushly throughout the summer, forming extensive carpets in backyard orchards and an informal ground cover under small deciduous trees.

Aggressive Rooting

• The creeping rhizomes of spearmint are one of the adaptations that help it form extensive colonies. These horizontal root systems store the energy produced by the plant each summer, preparing it for an explosion of growth the following spring. This adaptation also makes it easy for spearmint to become established in new areas and difficult to eradicate once established, much to the frustration of gardeners. Any bit of root that falls on the ground is likely to grow into a new plant and start spreading, as long as soil conditions are suitable.

Repeated Cutting

• The mat-forming habits of spearmint make it well-adapted to repeated harvesting throughout the growing season. Maintaining it this way keeps it looking lush and compact and means it can be used for fresh iced tea all summer. Every time it is cut to the ground, the roots immediately generate vigorous new stems from early spring to the first frost in fall. If it invades a lawn, it can be mowed along with the grass, releasing its stimulating fragrance each time it is cut.