Root rot attacks the roots of otherwise healthy plants and destroys a plant's ability to absorb nutrients from the soil. Caused by several fungi, root rot is distinguished by the presence of soft, mushy roots that appear black and slimy, while foliage appears wilted. Often mistaken as a lack of water in its initial stages, root rot progresses quickly and requires immediate attention if you hope to salvage your plants.
Drill holes in the bottom of pots or plant containers--if there are no holes--to allow excess water to drain when you water your plants. Cover the drainage holes with pebbles or broken shards of terra cotta pots to allow roots to rest above the water level.
Plant in containers with a mixture of one part potting soil, one part peat moss and one part perlite or vermiculite--a porous mixture that drains well. Add generous amounts of organic matter, like compost and well-rotted manure, to the soil in gardens to improve drainage.
Establish a regular routine of watering that allows soil to dry between applications of water. For gardens, water deeply once a week, moistening the soil to the root level. Water container-grown plants more frequent, following the recommendations for the specific plant. Always check the soil 2 inches below the surface with your finger to determine if the soil is dry and needs water.
Fertilize your plants, following the recommendations for each kind of plant. Plants that receive adequate nutrients have vigorous growth and resist disease. Avoid over-fertilizing, because this may cause stress and make your plants susceptible to root rot.
Follow spacing recommendations for your plants, to provide adequate air circulation. Planting too closely, or setting potted plants too close to each other, promotes disease.
Remove dead plant debris daily. Old leaves and fallen blooms decay quickly in moist soil and promote the growth of fungi known to cause root rot.