Desert rose (Adenium obesum) is a poisonous flowering plant species indigenous to Arabia and semi-arid regions of Africa. It’s a low-maintenance plant as it is resistant to drought and most diseases.
This plant is an evergreen succulent although it can drop its leaves during spells of cold weather. It grows to 3.3–9.8 feet in height, with thick stems and a swollen base. The leaves are leathery, 2–6 inches long, and 0.39–3.15 inches wide. The flowers are tubular, starting as white and about 0.79–1.97 inches long, with red or pink upper portions of 1.6–2.4 inches in diameter with 5 petals, similar to the flowers of the Plumeria and the Nerium.
This plant produces a poisonous sap that is used in poison arrows to hunt animals in Africa and also as a toxin for catching fish.
It is popularly grown indoors in temperate regions as well as easy to grow as a bonsai. There are several hybrids propagated by grafting. Plants germinated from seed generally develop the swollen caudex when young, although it takes time for plants grown from cuttings.
This plant will flower about 7-8 months from sowing, depending on growing conditions, to promote flowering, it needs 6 hours of sun and fertilization twice a year. If the plant has been repotted recently, it will spend its energy forming new roots rather than flowers. This plant is slow-growing, growing about a foot every year, and can live for literally centuries under the right conditions.
This plant loves lots of sunlight and bright light. It can be cultivated outdoors under the full sun during its active growing season. If you grow it indoors, it should get the same type of light as it gets outdoors – you can make up for any lighting shortcomings by using grow lights. It must be placed near a window or balcony so it gets as much light as possible. If you keep the plant in a warm, bright place indoors, it will keep on growing without becoming dormant.
Water it slowly and 2 or 3 times per week until water flows out of the drainage holes of the pot – this depends on how dry conditions are. Reduce watering to once a month if the plant becomes dormant in winter and its leaves start dropping. This plant dislikes water-logged soil.
If you’re uncertain whether the plant is getting enough water, check its trunk – a swollen trunk indicates that it has enough water.
Humidity isn’t important to this plant as it is used to living in a dry and hot environment.
This plant thrives in temperatures above 70°F, even if the temperature gets to 100°F, with a minimum temperature of 50°F. Temperatures below 40°F must be avoided as they can suffer damage.
This plant is a desert-dwelling succulent in its natural environment and well-draining soil is key to good health. The roots should never sit in water-logged soil.
Use soil specifically for cacti/succulents since it drains well. A little organic compost can be added to give the plant enough nutrients to keep it healthy.
Repot the plant as needed, generally when the roots outgrow the container and the plant gets root-bound. This could be once every year or once every other year. If you want the plant to stay small, you can reuse its present container. Keeping this plant root bound will slow down growth. When repotting this succulent, ensure the soil is totally dry before smoothly removing it from the pot. Remove old soil and any rotten or dead roots.
Place it in its new pot, spreading the roots and filling with appropriate soil. Don’t water the plant for a week or more to reduce stress/shock, then water it as usual.
This plant is primarily grown from cuttings and seeds, however, if you propagate the plant from a cutting, the new plant might not develop the characteristic bulging trunk that you would get from propagating it from seed. Before you start, you should have these items ready – gloves, sterilized pruners, a pot, and well-draining soil.
Use gloves since the sap is toxic and take a 5- 6 inch cutting from a branch. The cutting should dry for some time for a callus to form and plant in a well-draining mix. Water the cutting every day, making sure water flows from the pot. Rooting should take 2-6 weeks.
Spring is usually the best time to plant seeds. Use a well-draining mix with perlite or a sand and soil mix. Soak the seeds in advance for a few hours or a day, then insert the seeds two inches apart into the soil, lightly covering them with a layer of soil.
Water well and keep them under bright light in a warm place. Only water once the soil starts to dry out, but don’t allow the soil to get waterlogged. The seedlings will begin sprouting within a week or more.
The plant must be fertilized monthly with a suitable fertilizer while it is growing, diluted to half the usual dose.
Feed it once in two weeks in spring, when the plant wakes up from dormancy. Stop feeding the plant when the weather cools down and the plant goes dormant.
Cut off any damaged leaves or branches with clean cuts just overleaf nodes. Don’t forget to use gloves when pruning this plant.
Pests that often affect this plant are aphids, scales, mealybugs, and spider mites. Treat the plant using neem oil and/or insecticidal soap when you spot signs of an infestation.
The biggest problem this plant might face is root rot. Indications of root rot show up in yellow leaves or leaf drops. Root rot is caused by a fungus and you may be able to save the plant if you spot the signs early enough. Remove any damaged stems and leaves and examine the roots for any mushy, blackened roots and remove them. After applying a fungicide, replant the plant in well-draining soil. Root rot can be easily prevented by using free-draining, cacti/succulent soil, and never over-water this plant as it doesn’t like soggy soil.
Powdery mildew can make blister-like marks appear on leaf surfaces, leading to stunted growth and leaving a white powder-like substance on leaves, stems, and flower buds. This often spreads more during cool, wet nights and warm days. Powdery mildew doesn’t like water so mist the leaves and treat them with a fungicide. Prune stems and branches when they begin to bunch up. Adequate spacing between branches increases airflow and reduces the chance of powdery mildew afflicting the plant.