Ah… the desert roses… they are such enchanting plants, it’s almost impossible to resist their colorful flowers and sculptural stems. But what happens when we give in to this charm, buy a beautiful plant (which usually isn’t cheap), and simply the caudex rots? Has this ever happened to one of your plants?
I don’t know about you, but it has happened to me twice, and the feeling is devastating. A plant that you save up to buy, choose the most lush and beautiful seedling, and after it’s been a while in your home, it suddenly has the stem (or parts of it) rotted. But do not despair. Depending on the stage and extent of this rotting, it is possible to reverse the situation, as we will see later.
Before you start blaming yourself, thinking it was the fertilizer you used, or the evil eye from the neighbor, let’s learn a little about this species. Knowing more about the desert roses, the species Adenium obesum and its hybrids, allows us to take better care of them, so they grow and bloom healthy, free from pests and diseases.
Adenium plants also known as desert roses, are beautiful succulent plants with vibrant flowers that bloom in a variety of colors. However these plants can be susceptible to root rot if their soil stays too wet for too long. Root rot is a common problem that can quickly kill adeniums if left unchecked. Thankfully, there are several effective solutions for both treating and preventing rot in adenium plants.
What Causes Root Rot in Adeniums?
Root rot in adeniums is caused by fungi that thrive in wet, poorly draining soil. These fungi infect the roots and cause them to turn brown and mushy. As the roots rot away they are unable to take up water and nutrients leading to wilting and eventual death of the plant. Adeniums are particularly prone to root rot because they have fleshy roots that need soil that drains well. Sitting in wet soil for too long creates the perfect environment for fungal growth.
Some common causes of excess moisture leading to root rot include
- Overwatering – Watering too often and not allowing the soil to dry between waterings
- Poor drainage – Using a pot without drainage holes or dense soil that retains moisture
- Excess humidity – High humidity provides moisture fungi need to multiply
- Cool temperatures – Cooler temperatures slow evaporation and keep soil wet
- Insufficient sunlight – Low light prevents the soil from drying out quickly
Recognizing Root Rot Symptoms
It’s important to catch root rot early before it spreads through the entire root system. Some signs to look out for include:
- Wilting or drooping leaves and stems – Even if soil is wet, roots won’t uptake water
- Stunted growth – Rotting roots don’t supply nutrients for new growth
- Smaller than normal leaves – Lack of nutrients due to rotting roots
- Brown or mushy roots – Healthy roots are firm and white
- Plant collapses or dies rapidly – As fungus spreads through roots
If you suspect root rot, gently remove the plant from its pot and inspect the roots. Brown, mushy roots confirm a root rot infection.
How to Treat Root Rot in Adeniums
If your adenium plant has root rot, don’t panic! It can often be treated if caught early. Here are a few effective treatment methods:
Prune Off Infected Roots
Use sterilized scissors or shears to prune away any brown or mushy roots. Removing infected roots stops the fungus from spreading. Make clean cuts above rotted areas to preserve healthy roots.
Replant in Fresh, Well-Draining Soil
Repot the plant in a sterile potting mix, adding extra perlite or sand to improve drainage. Completely replace any old, wet soil to remove root rot fungi.
Let Soil Dry Out Completely
Allow the soil to dry out completely before watering again. Drying out the soil helps kill off fungi. Wait until the soil is completely dry at least a few inches down before resuming a cautious watering schedule.
Apply Fungicide Drenches
Water the soil with a fungicide like neem oil once a week for a month. Fungicides help destroy root rot fungi and stop infection. Be sure to follow label directions.
Increase Sunlight Exposure
Give the plant more sunlight if possible. Sunlight exposure helps dry out the soil. Place in the sunniest window or outdoors.
With quick treatment, many adeniums fully recover from root rot. Continue monitoring your plant closely and adjust care to prevent recurrence.
How to Prevent Root Rot in Adeniums
Prevention is the best cure for root rot in adeniums. With good cultural practices, you can keep root rot from ever occurring. Here are some tips for prevention:
Improve Drainage
Adeniums need exceptional drainage to avoid sitting in moisture. Always use pots with drainage holes and well-draining soil mixes:
- Amend soil with perlite or coarse sand to improve drainage
- Avoid dense potting mixes that hold moisture
- Never use a non-draining container like a bowl
Water Less Frequently
Overwatering is one of the quickest ways to cause root rot. Allow the soil dry out between waterings:
- Water only when top few inches of soil are dry
- Cut back on watering in winter when plant is dormant
- Check soil moisture by sticking your finger in soil before watering
Increase Sun Exposure
More sunlight exposure helps dry out soil between waterings. Provide at least 4-6 hours of direct sunlight if possible.
Avoid Excess Humidity
High humidity provides moisture fungi need to grow. Avoid misting the plant and place in drier indoor environments. Dehumidifiers can help lower humidity.
Monitor for Drainage Issues
Check that excess water can drain out the bottom after watering. Stagnant water can indicate a drainage problem. Repot in fresh soil to improve drainage.
Use Fungicide Drenches
Apply fungicidal drenches monthly as a preventative treatment during times of high risk for root rot like winter.
Disinfect Tools
Clean shears and other gardening tools with bleach to avoid spreading fungus between plants. Keep roots intact when repotting to avoid openings for infection.
By making a few simple adjustments to your adenium’s care, you can maintain the moisture balance these plants need to thrive. With well-draining soil and proper watering technique, you can avoid the fungal infections that cause frustrating root rot. Pay close attention to moisture levels and take quick action at the first sign of trouble. With vigilance and preventative care, your adenium will continue to grow strong and reward you with its exotic blooms.
The Habitat and Adaptations of Adenium obesum
Native to desert and semi-desert regions of Africa and the Arabian Peninsula, Desert Roses are plants perfectly adapted to water scarcity (and nutrients!). The rains in the regions where these plants naturally grow are scarce and poorly distributed, meaning not only is there little rain, but it also concentrates in a single season of the year. Furthermore, the soil where the Adenium grow is light, poor, sandy, and often even rocky.
There is very little organic matter available, since everything quickly degrades and dehydrates in this type of environment. The sun, the heat, and the winds often punish the wild-growing plants, and many times to protect themselves from the intense heat, they develop their caudex below ground level.
But what is the caudex?
The caudex is a modified structure, situated between the plant’s root and its stem, and its main function is to store water and nutrients to help the plant survive through tough periods and endure aridity. Looking at an unearthed plant, there isn’t a defined line separating the parts of the plant, so it is necessary to train the eye.
And look how interesting, not all desert roses have a caudex. This special structure only develops in plants that originated from seeds. Thus, when we propagate our desert roses from branch cuttings, the resulting plants, although healthy and beautiful, will never have a true caudex. Obviously, they can indeed develop beautiful and sculptural stems and roots, but never a chubby caudex as we know it.
What are the differences between the natural environment and that of our nursery?
Curiosities aside, both seed-born plants and those we’ve propagated from branches are prone to rotting. But if you paid attention to the plant’s habitat, you might have noticed some differences compared to the environment we provide for our potted plants. Generally, when cultivating in pots, we use substrates instead of soil.
The substrate is often rich in slowly decomposing organic material, so that it does not rot too quickly while still remaining airy, slightly moist, and drainable. Therefore, our substrates commonly include materials like pine bark, peat, macadamia husk, peanut shells, coconut fiber, charcoal, among other materials. To compose these substrates, we also add sand, perlite, crushed brick, gravel, expanded clay, etc., that is, materials that promote drainage, moisture, and aeration, similar to the materials we mentioned earlier.
Is this material similar to the poor desert soil?
Not even close! And it really needs to be quite different. This is important because we have to consider that our plants are not growing wild and free. On the contrary, they grow in pots, which are confined, and often shallow to promote drainage. To compensate for the differences between the natural and artificial environments, the development of substrates is crucial.
But why did I tell you all this?
It happens that few people take into account that substrates need to be changed annually (sometimes even biannually). Over time, they tend to decompose (the organic part) and compact (the mineral part), gradually losing their aeration and drainage capacity. As a result, our desert roses suffer and become susceptible to rotting. And why are aeration and drainage so important for our plants?
The roots and the caudex of the desert roses, contrary to what one might imagine, need to breathe fresh air. Even though they are below the soil line, these organs require oxygen to stay healthy. Compact soil does not allow air to circulate and ends up favoring the appearance of many opportunistic pests and diseases.
To complete the picture, it is common for plants that grow in old substrate to wilt because their diseased roots gradually lose the ability to absorb water and nutrients. When we see our thirsty plants, we end up watering them more frequently, further damaging the aeration and causing the water to become waterlogged in the substrate.
Other Causes of Rot
One of the main reasons for stem and root rot in desert roses is the aged substrate. But that’s not the only thing that can cause the problem. Monsoon seasons, with heavy rains, as well as unbalanced fertilizations, can also lead to the same issue, and we need to be vigilant to avoid disaster. As a succulent, the desert rose must be protected from intense and frequent rains and requires careful fertilization, preferably with little to no organic matter, and well calculated, to avoid excesses, especially of nitrogen.
The plant’s dormancy period is even more delicate. As the metabolism of the plants is reduced during this time, they become even more susceptible to rot of the caudex.
In addition, if the plants are infested with pests, such as root mealybugs, for example, they also become more vulnerable, as these insects tend to weaken the plants and create entryways for the rapid spread of fungi and bacteria, causing irreversible damage.
Careless management, using dirty knives, scalpels, and scissors, as well as lifting the caudex and pruning with incorrect techniques and at inappropriate times, is also a recipe for the onset of rot.
Better than treating our sick desert roses is not having to face this serious problem at all. Rot is a stealthy disease that can often catch us by surprise in plants that seemed healthy. Believe it or not, it can’t always be prevented. But in most cases, prevention plays a crucial role, preventing our treasures from being mutilated or killed by rot of the caudex and roots. Based on what we’ve learned about the habitat and cultivation conditions, it is good to:
- Use perfectly drainable and airy substrates, with good granularity and sifted (dust-free);
- Change the substrate annually in the spring;
- Fertilize with fertilizers specific for desert roses, in the dose recommended by the manufacturer, and during the growing season, suspending fertilization during dormancy;
- Avoid using worm castings, vegetable cakes, unripe manures, and other materials that can rot in the substrate and make it pasty;
- If using organic fertilizers, prefer well-ripened or even liquid ones, such as diluted biofertilizer;
- Apply diatomaceous earth on the substrate, to strengthen the stems with silicon, and keep pests away from your plants;
- Water the plants deeply and abundantly, but always wait for the substrate to completely dry out between waterings;
- Always use sterilized cutting tools for pruning;
- Lift the caudex only in healthy plants;
- Use wide and shallow pots, to promote drainage;
- Always choose pots proportional to the size of your plants, avoiding pots that are too large for small plants;
- Maintain good pest prevention and treatment management;
- Use hydrogen peroxide solution during periods of stress and frequent rains. (see the recipe here)
If you live in an area prone to frequent rains at certain times of the year, it is advisable to water with hydrogen peroxide solution or some systemic antifungal during these periods. Talk to an agronomic engineer at the farm supply store, so they can guide you in buying and diluting the best product for this purpose. On Amazon, you can find excellent systemic antifungals ready for use, and approved for gardening.
Desert Rose Root Rot | Saving your Adenium Obesum
FAQ
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