The many varieties of jasmine plants are prized by gardeners for their vibrant blooms and strong, sweet scents. Winter jasmine is particularly popular as it is one of the few plants that flowers through winter. Many types of jasmine are tender however, and can be damaged or killed by cold weather. Even winter jasmine may not survive a particularly harsh winter and other potential problems include disease and pest infestation.
Many species of jasmine are suited to mild or tropical conditions and will not usually survive winter in a colder climate such as the UK. Winter jasmine is fully hardy and can be grown outdoors throughout the UK, according to the Royal Horticultural Society. The common summer jasmine is frost hardy and can be grown outdoors in milder parts of the UK. Most other varieties are tender, meaning they don't deal well with the cold. If an unsuitable variety was planted outdoors and looks dead after the winter, there's a good chance that it is. You can usually check if a plant has survived by scraping off a small area of tissue, according to the University of Florida. If you see greenish or moist, light-coloured tissue, your plant is still alive.
All varieties of jasmine benefit from pruning. For most varieties this should be done following their blooming period in late summer. The winter jasmine should be pruned in early spring following its own bloom. Failure to prune could result in a plant that looks dead and is covered in dry, withered leaves and shriveled flowers. A damaged or overgrown winter jasmine can be hard pruned by cutting back every stem to within about 2 feet of the ground. It will usually take 2 to 3 years for a hard pruned plant to flower again.
Jasmine plants can be susceptible to conditions such as mildew and stem blight. These are more common in damp or humid conditions and may take hold during a mild, wet winter. Jasmine should not be over-watered and should have adequate drainage. If your plant is affected, cut away and discard discoloured stems and treat with a suitable fungicide.
The most common pest to infest jasmine plants is the spider mite. Spider mites are dormant through the winter but re-emerge in spring and can quickly infest a plant. They may also infest plants in warmer settings such as a heated greenhouse all year round. If your plant is infested with spider mites you should cut it down to the ground after blooming and discard the infested plant material, according to Clemson University.