Carissa plants, also known as Natal Plums, are evergreen shrubs valued for their star-shaped, fragrant white flowers and colorful, edible fruit. They add ornamental value to gardens and thrive in warm climates, making them a popular choice for their beauty and resilience.
Understanding Carissa
Carissa, or Carissa macrocarpa, is an evergreen shrub native to the coastal regions of South Africa, specifically the KwaZulu-Natal province, which gives it the common name Natal Plum. It typically grows as a dense shrub between 2 and 7 feet tall, though some varieties can reach up to 30 feet, forming a small tree. Its branches are dense and woody, featuring distinctive forked or Y-shaped thorns.
Carissa plants have glossy, leathery, dark green leaves and highly fragrant, white, five-petaled, star-shaped flowers. These blossoms often have a jasmine-like scent that intensifies during the evening. After flowering, the plant produces oval fruits resembling small plums, which ripen from green to a vibrant red or purple. Carissa is well-suited for USDA hardiness zones 9 through 11, indicating its preference for warmer climates.
Caring for Carissa
Light Requirements
Carissa plants perform best in full sun, receiving at least 6 to 8 hours of direct sunlight daily. While they tolerate partial shade, insufficient light can reduce flowering and fruit production. For optimal growth and abundant blooms, choose a sunny location.
Soil and Watering
Natal Plums adapt to various soil types but thrive in well-draining, sandy soil that is neutral to slightly acidic. Good drainage prevents root issues. Once established, Carissa plants are drought tolerant, making them suitable for drier conditions. Allow the soil to dry out completely between waterings to prevent overwatering and root rot. During hot summer months, more frequent watering may be needed, but ensure the top inch of soil is dry before rewatering.
Fertilization
Carissa plants benefit from moderate fertilization during their growing season. A balanced NPK fertilizer supports general health and encourages fruiting. Apply fertilizer in spring or early summer. Be aware that excessive nitrogen can lead to lush foliage at the expense of flower and fruit development.
Pruning and Shaping
Pruning Carissa plants helps maintain their desired shape and promotes bushier growth and increased flowering and fruiting. Major pruning is often done in late winter or early spring before new growth begins, or after the peak blooming and fruiting season ends in late summer. This practice involves removing dead or damaged branches and thinning out crowded areas to improve air circulation and light penetration within the plant. When pruning, using sterilized tools helps prevent the spread of diseases.
Uses of Carissa
Carissa plants are widely used in landscaping for their aesthetic and practical qualities. Their dense foliage and thorny branches make them an effective choice for hedges, privacy screens, and barrier plantings. They are also suitable for foundation plantings or as specimen shrubs. Due to their tolerance for salt spray and drought, they are well-suited for coastal gardens and xeriscape designs.
The oval, red fruits of the Carissa plant are edible when fully ripe. Their flavor is often described as a blend of cranberry and raspberry, with hints of apple or cherry. They can be consumed fresh or used in culinary applications like jams, jellies, pies, and sauces. The fruit is a good source of Vitamin C, magnesium, and phosphorus.
Common Considerations
Carissa plants have prominent, forked thorns that require caution when handling, especially during pruning or when planting near walkways. The plant also produces a milky white sap when stems or leaves are broken, which can be irritating to the skin and eyes.
While robust, Carissa plants are susceptible to a few issues. Overwatering can lead to root rot, so proper drainage is important. Pests like scale insects and mealybugs can appear but are manageable with horticultural soap. Fungal issues such as leaf spot may also occur. In warm, humid climates, Carissa has the potential for self-seeding, which may require management to prevent it from becoming weedy.