From our perspective as plants, light is our primary source of energy. Both peppermint (Mentha × piperita) and spearmint (Mentha spicata) share a high demand for it. To synthesize the essential oils that give us our distinctive aromas and flavors, we require a minimum of 4-6 hours of direct sunlight daily. A south-facing window is ideal. Without sufficient light, our stems will become long, weak, and leggy as we desperately stretch to find a photon source, and our leaf production will be sparse. If natural light is inadequate, you can supplement it with a grow light placed about 6 inches above our canopy for 12-14 hours a day.
Our root systems are particular about moisture. We enjoy consistently damp soil, but we absolutely despise having our roots sit in waterlogged, soggy conditions, which leads to root rot—a fatal condition for us. The key is well-draining soil. A standard potting mix amended with perlite or vermiculite provides the perfect balance, retaining enough moisture while allowing excess water to escape. Water us deeply when the top inch of soil feels dry to the touch. You will notice our leaves begin to droop slightly when we are thirsty, a clear signal that we need a drink.
We are temperate climate plants at heart. We prefer daytime temperatures between 65-70°F (18-21°C) and slightly cooler nights. This mimics our natural outdoor growing season. While we can tolerate typical indoor air, we truly thrive with higher humidity levels, which keep our leaf edges from turning brown and crispy. Placing our pot on a pebble tray filled with water (ensuring the pot is not sitting directly in the water) or grouping us with other plants creates a beneficial microclimate. Please keep us away from hot radiators or cold, drafty windows, as extreme temperature fluctuations cause us significant stress.
This is the most crucial distinction from our point of view. Both of us are prolific spreaders by nature, sending out runners (stolons) just below the soil surface to colonize new territory. However, peppermint is notoriously more vigorous and aggressive in its spread. If left unchecked in a shared container, peppermint will almost certainly outcompete other plants for resources. Therefore, the universal rule for growing any mint indoors is to provide each plant with its own dedicated pot. A wide, shallow pot accommodates our horizontal root growth better than a deep, narrow one. This containment is non-negotiable for our long-term health and your sanity.
Harvesting is not just for your benefit; it is essential for our well-being. Regularly pinching off the tips of our stems or harvesting leaves encourages us to become bushier and fuller, rather than tall and spindly. Always trim just above a set of leaves (a node), as this is where new growth will emerge. For both peppermint and spearmint, the optimal time to harvest is just before we flower, when our essential oil content is at its peak. This practice redirects our energy from reproduction back into vegetative growth, resulting in more lush foliage for you to enjoy.
