Carissa (Carissa macrocarpa) is native to South Africa, but they are a long time favorite of our area and you will find them planted along the eastern coastline of Florida and a couple places along the western coast of Southwest Florida. One of the large varieties that grows well in South Florida is the natal plum cultivar known as large num num in its native Africa. This cultivar has small white flowers that carry a citrus fragrance all year long and small plum-shaped fruit. Although the fruit can be made into a jelly, when the fruit is small it can be poisonous. I would recommend just appreciating their small grape like reddish appearance instead. Another popular variety for our area is the emerald blanket, a dwarf cultivar that has a low spreading growth pattern. This variety makes an excellent choice for a low groundcover shrub, providing a rich, dark green swath of color.
Carissa can survive in sandy soil and has a high tolerance for salt which makes it ideal for island plantings. But, be warned of its small sharp 1-2 inch thorns that tend to hide underneath the small glossy leaves. On the natal plum and boxwood beauty cultivars, the leaves as well have spiked ends, and are not recommended next to a walkway. Although, if you are looking for a buffer plant that could be kept a couple feet in height and that can deter intruders say along a busy pedestrian path the natal plum might be a good choice for you.
If you are artistic in nature and have the patience for the art of bonsai, trimming plants with a bonsai appearance could be an interesting choice. There are also smaller varieties bonsai, prostrate or horizontals (natal creeper) that are smaller in size and can be maintained around 2 feet in height. Even left to their natural grown pattern, carissa is a good choice in an Asian themed garden because of its clean, compact leaf patterns. With just minor trimming to maintain a nice shape, you can keep these plants looking good. They require just basic plant care, regular watering (letting them dry out between watering) and fertilizer a couple times a year to keep them looking healthy.
This column is a joint effort by all at In The Garden, Sanibel’s local garden center located at 3889 Sanibel Captiva Road, Sanibel Island, Florida.