What Is Killing My Sage Plant?

Sun

• Other plants, such as parsley and mint, prefer indirect sunlight or partial shade, but such low-light environments can be detrimental to a sage crop. Place sage in full sunlight to promote healthy growth. Never allow fertilizer to rest on the leaves of the sage plant. Chemicals in fertilizer can burn the sage.

Water

• Sage requires well-draining soil to thrive. Over-watering is a likely cause of death for sage plants as excess moisture can cause the root system to rot. To avoid over-watering your plants, use a well-draining soil, such as nitrogen-infused clay loam. Water sage only once or twice a week when the soil becomes powdery and colorless.

Climate

• Sage is a hardy plant that can withstand brief periods of drought, flood, little sun and cold, but repeated exposure to these conditions will kill sage plants. If you live in a region with severely cold winters, consider planting your sage in a pot so that it may be moved indoors during inclement weather. Plant sage only after the danger of frost has passed. You may start seedlings indoors four to six weeks before the last frost.

Old Age

• Eventually sage plants die of old age. This slowing of growth rate and degradation of flavor can occur in the third or fourth growing season. To prolong the life of your plants, wait for the blossoms to die and then trim the plant to half of its size; this will help conserve the plant's resources. Restart your sage crop by taking cuttings from your plants in the spring and replanting them.

Fungi

• Damping-off fungi and powdery mildew can kill sage. These fungi can be transferred to sage from contaminated soil. Wet roots and stagnate air can facilitate the growth of these pests. To prevent fatal fungal infections, do not over-water sage, place plants in an area with good air circulation and use sterilized soil.

Pests

• Whiteflies, spider mites and mealybugs may also infest sage plants. These pests are difficult to control without the use of pesticides. Prevent infestation by purchasing full-grown sage from a reputable dealer and removing contaminated plants from the crop. Wiping down or spraying leaves with a steady stream of water can also deter pests. For mild infestations, remove contaminated leaves and seal the plant in a bag. If you use your sage for cooking, use insecticides sparingly or avoid them entirely.