If you like fragrant shrubs, you’ll love the Natal plum bush. The fragrance, which resembles that of orange blossoms, is especially intense at night. Read this article to find out more.
I. Appearance and CharacteristicsÂ
Carissa macrocarpa is a shrub native to tropical and southern Africa. It is commonly known as the Natal plum and, in South Africa, the large num-num. In Zulu, as well as in the Bantu tribes of Uganda, it is called Amathungulu or umThungulu oBomvu. In Afrikaans the fruit is called noem-noem.
C. macrocarpa deals well with salt-laden winds, making it a good choice for coastal areas. It is commonly found in the coastal bush of the Eastern Cape and Natal. It produces shiny, deep green leaves and showy white flowers whose perfumed scent intensifies at night. Like other Carissa species, C. macrocarpa is a spiny, evergreen shrub containing latex. They bloom for months at a time. The ornamental plump, round, crimson fruit appears in summer and fall (autumn) at the same time as the blooms. In moderate, coastal areas the fruits appear throughout the year.Â
Some claim that other than the fruit, the plant is poisonous. However, this claim is a myth, possibly based on similarities to other plants with milky sap. The College of Agricultural and Environmental Sciences at University of California, Davis rates the plant as mildly toxic. It appears in the South African National tree list as number 640.3.
II. How to Grow and Care
Sunlight
Natal plum plants like to grow in open spaces and can tolerate harsh sunlight.
Their dark green foliage may indicate that they can do well in low-light conditions, but they will not thrive as well as they do outside in the sun.
Still, they grow healthy foliage when brought indoors or grown in heavy shade.
You must note that these plants will only bloom and fruit when provided adequate sunlight.
Their blooming ability is seriously hindered when placed in the shade.
If you live in a cold climate, you can bring your Carissa macrocarpa indoors to protect it from the frost.
However, you must give it a window spot that gets at least 4 hours of sunlight every day to keep the sun-loving plant healthy and happy.
If you can’t find a sunny spot indoors, then you’ll have to make do with a grow light to help your Natal plum survive the winter.
Temperature and Humidity
The Natal plum thrives in temperatures that range above 68 degrees Fahrenheit during the day and between 50 and 65 degrees at night. They are quite sensitive to cold—young plants cannot tolerate temps below 30 degrees Fahrenheit, and established plants can be killed by temps below 25 degrees. These plants are equally tolerant of humid and dry air conditions, provided they get enough soil moisture.
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.
A deep watering every time the soil dries out is just what this shrub needs.
Ensure that you are not watering the plant when the soil is already moist.
This plant can survive many things, but if there’s one thing it can’t survive, it’s over-watering.
An excellent method to deep water Natal plum is through soaking. Before you water the plant, check if the soil carries any moisture at all.
If it seems bone dry, place the pot in a tub of shallow water so that it soaks up all the water it needs through the drainage hole.
Soil
Carissa Macrocarpa does not have very specific soil requirements and can tolerate any kind of soil as long as it drains well. The plant can tolerate soil pH levels ranging from 6.2 to 7.8. Natal plum is particularly well-suited for seaside plantations as it likes sandy soil.
Being native to coastal regions, Carissa macrocarpa naturally grows in sandy soil with high salt content.
But sandy soil is not essential for this plant to grow well.
This ornamental plant can tolerate a wide range of soil types, the only requirement being good drainage.
The remarkable thing about Natal plum plants is that they can do well in a wide range of pH levels.
They can survive in mildly acidic as well as mildly alkaline soil, from soil pH levels ranging from 6.1 to 7.8.
However, the plant will suffer from chlorosis in highly alkaline soils that are more than pH 8.
Apart from tolerating a wide range of pH levels, Natal plums can also tolerate high levels of salt in the soil, which are otherwise fatal for other plants.
If planting in containers, Carissa macrocarpa will surely do well in any houseplant potting mix.
However, some varieties are susceptible to root rot if the soil does not drain well.
You can add a few parts of sand to the soil if you feel the soil gets too compacted.
Fertilizing
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.
As a plant that can grow well in salty and dry soil, the luxury of growing in regular garden soil is more than enough to sustain a healthy Carissa macrocarpa.
However, you can make its life even better my moderate applications of organic fertilizer.
Although it can tolerate slightly alkaline soil, this plant grows better in soil that’s slightly on the acidic side.
For this, you could feed your Carissa macrocarpa coffee grounds or other acidic fertilizer that lowers the soil PH levels.
Pruning
The Carissa macrocarpa responds very well to pruning and can be easily shaped into a hedge or Bonsai tree. It can be pruned at any time of the year. Pruning in spring or summer will result in vigorous growth of new buds.
This beautiful plant typically grows horizontally, and you might find it taking over your garden space very soon.
It can always be pruned back to shape, and the good news is that it will spring back with a more gorgeous shape and foliage than before.
Propagation
Natal plum is easy to propagate using stem cuttings, which can be taken at any time of the year. Here’s how:
- You will need pruners, rooting hormone, sand, peat moss, loam, and a glass or small pot.
- Select 4- to 6-inch cuttings, treat them with rooting hormone, and either insert them in moist sand or place them in a glass of water.
- Once the roots appear, plant the stems in a mix that consists of one part sand, one part peat moss, and two parts loam.
- Keep the new cuttings moist (not wet), and provide bottom heat with a heating pad until new growth begins.
- At this point, the cuttings can be potted into larger containers or transplanted into the garden.
Potting
To pot a Natal plum, use a pot that is at least 30% bigger than the initial rootball size to sustain healthy root growth. The pot must have drainage holes at the bottom. Using a clay pot is recommended. For growing as a Bonsai, choose a pot that can support wide root growth to balance the plant.
Carissa macrocarpa has a horizontal growth habit. For the branches to grow horizontally, the roots have to do the same to balance the plant.
Along with horizontal root growth, the roots of a Natal plum also go deep, which makes the shrubs stand firmly in strong coastal winds.
To cater for healthy root growth, choose a large pot for your Natal plum.
However, if you’re growing it as a Bonsai, get a pot that is wide enough so that the roots can grow horizontally.
Pests and Diseases
You should not have many pest problems with this shrub. You may see Florida red scale (Chrysomphalus aonidum) or aphids, which can be removed with horticultural soap. Fungal infestation may occur if a Natal plum is overwatered.
Overwintering
To overwinter Natal Plum indoors, it will need 4 to 6 hours of sunlight and adequate humidity, supplied from a humidifier or a pebble tray.
III. Uses and Benefits
- Ornamental usesÂ
Natal plumb is used frequently in commercial landscapes in warmer climates, where its pretty, white, star-shaped flowers and fragrance are highly prized.
- Culinary uses
The edible, bright red, plum-shaped fruit tastes like cranberries, and you can use it to make jam or jelly.
A traditional food plant in Africa, this little-known fruit has potential to improve nutrition, boost food security, foster rural development and support sustainable landcare.
IV. Harvesting and Storage
With a minimal yield of 3 tons per hectare under commercial production in South Africa, the productivity is considered as high. The main fruit production is in summer with slightly varying ripening times. So each fruit must be picked when it is ripe. Under good growing conditions the plant also produces many fruits during the off-season. During the harvest attention must be paid to the ripe fruits’ skin as it can be easily bruised and is highly perishable.