Haworthia thrive under the correct environmental conditions: well draining pumice-rich soil, sufficient light and temperatures and correct watering. But in the long term, some individuals may become prone to dormancy syndromes that can lead to dehydration and death. Some plants may lose their plumpness and take on a more dehydrated look. Dry older leaves are often visible.
In this blog, I will guide you through diagnosing and managing this problem to ensure the ongoing health and beauty of plants that have started down this path.
Underground Stem formation
From my observations these dormancy/dehydration problems are usually linked to the formation of an underground stem. The stem in Haworthia is normally very small and hidden. In cultivation sometimes the older leaves will die faster than than the stem can be absorbed. Over time an underground stem forms. When this happens it interferes with the ability of the plant to form new roots, absorb nutrients and grow new leaves. I have found that even if roots are still present, the underground stem still negatively affects the health of the plants.
Recognizing the signs:
Watch for plants showing signs of dehydration and slowed leaf production. They might look like this:
Unpot the plants and examine the roots.
The solution:
Carefully slice the stem straight across and flush with the bottom leaves using a razor blade or sharp knife (exercise caution to avoid injury). You may notice young roots at the base of the leaves; try to retain these during slicing.
After slicing the plant should look like this:
At this point you can allow the plant to heal for a day or two or immediately pot it up. I have experimented with dipping the end in rooting gel or rooting powder but in my experience doing this will not increase the chance of success and I suspect it may have the opposite effect. I pot them up in lightly moistened soil and secure them to the pot with wire. The wire is necessary because when haworthia start to make their thick roots the roots can push the plant above the soil. Here is a picture of a plant where this has happened:
Securing the newly trimmed plant with wire will prevent this from happening. Here is a newly potted up plant after this procedure:
Keep the plants in a shady location until they plump up. Start watering after about 10 days. The best time to do this procedure is during the autumn and winter. Results will be less successful during the hot summer months. I add a beneficial microbe product "Root shield" which colonizes roots and prevents harmful fungi from infecting. This may increase my success rate. In general I find that about 75% of the plants will plump up and survive:
After the plants form new roots and plump up remove the wire:
I am actively engaged in experiments to identify effective cultivation practices or treatments that could mitigate this issue. The problem might have a genetic basis, as it seems to occur more frequently in splendens and splendens hybrids. My current hypothesis links the problem to excessively rapid leaf senescence, and I am testing various treatments, including hormonal interventions, to prevent its occurrence.