Soil: Both herbs need to be in a well-draining soil, or they may be more susceptible to rot or diseases/pests.
On the other hand, overwatering can also cause the leaves to rot and turn black.Īs for the sage, this plant does not like soil to remain wet – after watering, let the top of the soil dry out before watering again. Mint likes a moist soil, and excessively dry soil could contribute to the leaves turning black. Water: Watering – either too little or too much – could be an issue. Also, the leaves should not touch the window, as they would be affected by cold winter temperatures or hot summer temperatures. Herbs generally like temperatures of around 18-21 degrees C (65-70 degrees F) during the day. Heat: However, if it’s too hot in the sunroom, the plants could be suffering from the heat. It sounds like the mint and sage are getting enough sun, especially in the past month or so (it is late April). Light: Adequate sun exposure is critical in maintaining herb health. They may not be as well-suited to growing indoors.Ĭonsider the following factors, one or more of which could be responsible for the black leaves: Both herbs are hardy perennials, happy to grow outdoors.
