Adenium is a small genus of bonsai trees known for their beautiful flowers and bulbous stem (caudex). Adenium obesum, or desert rose, is the plant that is most frequently grown. While pink flowers are the most common, hybrid varieties with red, white, and deep purple flowers are also available.
These lovely plants are native to Africa and the Arabian Peninsula. They are frequently grown as houseplants in temperate climates where they grow well if given full sun. Desert rose bonsai can grow to five feet tall in a pot. However, they can easily be grown as smaller trees.
These plants are grown much less frequently as bonsai subjects compared with other kinds of trees. This is unfortunate since the desert rose has many qualities that make it an excellent bonsai tree.
One note of caution if you grow this plant. Be careful when pruning because the sap is poisonous. In fact, the sap is used throughout Africa to poison arrows to hunt large game. If you have small children or pets that like to graze on plants, consider putting your desert rose bonsai tree out of their reach.
Care Guidelines For Adenium Bonsai
Adenium plants make ideal bonsai plants because of their bulbous stems, pretty flowers, and their ready growth in pots. The plants quickly grow to about eight inches tall.
If you live in a warm climate, you can grow the desert rose bonsai outside all year long. However, if you live in a temperate climate, you can grow these plants in your yard from spring through fall if you provide some afternoon shade.
The ideal temperatures for the desert rose range from 5ºC (40ºF) at night to 32ºC (90ºF) during the day. These plants cannot tolerate temperatures below 5ºC. Therefore, you should bring your Adenium inside once the temperatures start dropping. Make sure to treat them for insects before you bring the plants into your home or greenhouse.
Once inside, the desert rose requires a lot of light. A sunny window in a southern location is ideal. If you cannot provide a lot of sunlight, you may need to grow the plant under grow lights.
Don’t be alarmed if your Adenium bonsai loses its leaves over the winter.
This is perfectly normal if you don’t live in a tropical climate.
If you plan on placing your bonsai tree outside once the temperatures warm up, slowly adjust it to the amount of light outside. That way your plant will not be damaged by the sudden shock of intense sunlight found outdoors.
Since the desert rose is a succulent, it needs water less frequently than many other types of bonsai trees. The caudex holds water, and if you water too frequently, your plant could develop root rot.
You should thoroughly water your Adenium bonsai tree every 7-10 days. Place the pot in water for half an hour, and then let it drain. Keep an eye on the soil to ensure that it does not get too dry.
During the winter, you may be able to water less frequently since the plants are dormant. You should consider placing the plant on a shallow tray of gravel and water to give it some extra humidity over the winter.
Soil And Fertilizing
Fertilization is important to keep your desert rose lush and green especially since these bonsai trees are usually grown in small pots.
You only need to fertilize from the spring to the fall since these plants go dormant in the water. Fertilize once a month with liquid fertilizer. It is important to only use half strength fertilizer since the plants are small.
If you grow your desert rose outside, you can use a solid organic fertilizer instead of a liquid one.
Do not fertilize the plants during the winter.
Since the sap is poisonous, wear gloves when pruning your desert rose bonsai. Additional recommendations include wearing goggles and protective clothing. You can prune year-round, but some experts recommend pruning early in the spring before the plant starts its new growing season.
This is because pruning stimulates the flowers to appear on new shoots.
Cut back the long shoots and damaged parts just above a leaf node or at the junction of branches by making smooth cuts with a sharp knife. Wash up thoroughly when you are done to get rid of any sap that could be on your gloves.
Repot your adenium bonsai every two to three years. Late spring or mid-summer is considered the best time to repot. Wait until the soil is dry before you repot. Gently remove the plant from the pot along with the soil around its roots. Rinse the soil off the roots. Next, prune the roots. Remove about one quarter of them from the sides and bottom.
Desert rose grows well in shallow pots, which give the caudex a chance to fully develop.
Choose a pot that is at least two-thirds as wide as the height of the tree.
Cover the drainage holes with a plastic screen or large rocks. Add a thin layer of gravel over the whole surface of the pot’s bottom, so it will drain well. Then add a layer of potting mix that drains well, so that the tree will be at the proper height. Add more soil around the mass of roots and make sure that there are no air pockets.
Some experts say to immediately water it thoroughly by submerging the pot in water and then letting it drain. Others say to wait about a week before watering the repotted plant.
It is a good idea to add some type of covering to the surface of the pot. This can be bark, moss, or stones. Don’t be worried if the plant doesn’t bloom for a while. It may be using its energy to grow new roots.
You can propagate a desert rose bonsai from seeds or cuttings. Using cuttings is an easier process, but the tree may not develop a bulbous caudex as quickly. Nurseries typically propagate these plants by grafting.
You can propagate from cuttings by taking a six-inch-long cutting from the tip of a branch. Give it a couple days to dry out in the shade, and then slightly wet the tip and dip it in rooting hormone. Plant the cutting in soil so that the cut end is just below the surface.
Place it in bright light, water it lightly, and mist the cutting daily for about two weeks.
The cutting should grow roots in one to two months.
If you want to grow desert rose from seeds, try to find a reputable dealer since fresh seeds are much more likely to germinate. Put the seeds in a medium that drains well like a mix of sand and soil or pure perlite. Lightly cover the seeds. Water from both below and above every three days until the seedlings start growing (typically in a week).
Then place them on a heating pad to keep the temperature above 27ºC (80ºF).
Potential Pests And Diseases
Desert rose that is very healthy rarely suffers from pest infestations or diseases. However, trees in weakened conditions can be afflicted by spider mites, aphids, and/or mealybugs.
If you see mealybugs, quickly remove them with rubbing alcohol. If the plant is infested with spider mites or aphids consider using a low toxicity fungicide such as neem oil.
Desert rose bonsai trees that are kept too moist can contract root rot. Unfortunately, you will probably not be aware of this until the plant collapses. At that point, throw the plant out, sterilize the pot with 70% rubbing alcohol or 10% bleach, and start over!
If all the leaves are turning yellow, the plant may be getting too much sun or heat, and you should move it to a shadier spot.
Wiring Your Bonsai
Desert rose requires more care when wiring than many other plants. Be careful not to wire too tightly since the branches easily scar.
Q. When Will My Desert Rose Bonsai Bloom?
A. A healthy adenium or desert rose blooms during the summer throughout the fall with proper care. The flowers can be white, pink, deep purple, or red. A desert rose bonsai does best in full sun.
Q. How Often Should I Water My Desert Rose?
A. It is critical to not overwater a desert rose, since these plants are succulents and can rot easily if given too much water. Water every 7 to 10 days during the growing season and less frequently during its dormant period in the winter.