What Do You Do to Frozen Gardenia Bushes?

Treatment and Recovery

• During severe freezes, gardenia can be killed back to the ground. Once weather warms new shoots sprout. Keep the old, damaged growth in place as it provides the tender shoots with some insulation. Once new shoots have leafed out and gained some strength cut back the old growth. Provide your plant with water during the recovery period. Keep it irrigated and inspect for possible insect damage or bacterial and fungal growth. Weak gardenia are susceptible to stem cankers, root rot and nematodes. Should symptoms such as basal stem growths, dropping leaves and uneven growth occur, spray your gardenia with recommended amounts of the appropriate fungicide or insecticide. Take a sample of the diseased plant to your local university extension for proper diagnosis and recommendations.

Prevention

• The cultivar Kleim's Hardy can withstand temperatures as low as 10 degrees Fahrenheit but even this cold hardy cultivar can use some protection. Site gardenias in areas with dappled shade. Mulch the base of the plant. Mulch retains even moisture, which helps strengthen root systems and keeps them from succumbing to cold temperatures. Mulch also provides a layer of insulation. Do not fertilize your gardenias late in the growing season. Fertilization encourages new growth and new growth will not be hardy enough to withstand the coming winter chill.

Pruning

• Damaged branches are cut back once new growth has matured but be aware of insect and other contamination to wounded branches. Prune branches back with clean cuts and use sterilized equipment to prevent the spread of mold, spores and other contaminants. Dip pruning equipment in a solution of 10 percent bleach or 70 percent rubbing alcohol to avoid contagion.

Considerations

• Water gardenias with drip irrigation. These above ground, low-level irrigation systems provide even moisture at the plant's base. Overhead watering increases the risk of powdery mildew and molds. Fungal spores are often water-borne and travel from upper leaves, via water, down to a plant's base and root system. Keeping plant's disease free during the growing season gives them a better chance of surviving the winter.