Watering
Carissa macrocarpa does not require a lot of water and is known for its drought tolerance. Once established in the ground, this shrub might never need you to water it. In containers, it requires water bi-monthly in winters and weekly in summers. 
This plant has evolved to grow in harsh conditions and requires water sparingly.
The close-set and relatively thick foliage of the Natal plum allows the coastal plant to reduce its transpiration rates to the bare minimum. 
The African shrub is a popular choice in xeriscaping, which is designing plantations that require no irrigation. 
 
Temperature
The Carissa macrocarpa is a heat-loving plant that cannot tolerate temperatures below 50°F(10°C). Ideal growing temperatures range from 65°F up to 100°F (18-38°C). This plant does well in USDA Hardiness Zones 9b-11.   
 
Fertilizer
Carissa macrocarpa is not a particularly heavy feeder and can do quite well without any fertilizing if planted in the ground. However, it can be fertilized with general-purpose fertilizer to boost its growth and blossoms. Fertilizer is especially needed when growing Natal plum in pots. 
 
Light 
Natal plum plants love direct sunlight for a major part of the day. While they need at least 4 hours of sunlight every day, these plants can do well in shady conditions too. However, they will not flower and fruit as well in the shade as in the sun.