Written by Harry Lewis
Previously, I discussed reasonably advanced techniques for the propagation and breeding of Haworthia (Read the articles here). I realized I neglected the basics in favour of this advanced information, so for this article I will take a few steps back, and start at the beginning.
Most Haworthia are not fussy plants. They can survive with some level of neglect, though it is important to note that they will not thrive unless they are properly taken care of. There are a variety of factors to consider when caring for Haworthia, including:
From my own experience when speaking with new hobbyists, is that there are two important factors that are often glossed over or ignored when caring for plants.
The first is the amount of light the plants receive. When I have doubts about how to care for my plants, I always think back to how they would occur in their natural habitats. Haworthia tend to grow under large shrubs or in well-shaded areas, and do not tolerate high levels of sunlight. To simulate this, one can either place their Haworthia in a well-shaded spot in their garden, perhaps under a tree. If your plants are in a greenhouse, use shade-cloth to filter light.
Haworthia in the greenhouse at Living Desert Plants, planted in various mixtures of Akadama and crushed LECA, with a few test pots of pumice and Akadama mixes
Note the word “filter” rather than “block”. If you block sunlight from reaching a plant, it will be unable to use photosynthesis to produce energy, and will eventually die. I have noticed a trend of people recommending bright, indirect light for Haworthia, which is in my opinion inadequate if you want the plants to thrive. Only providing indirect light for your Haworthia will cause them to “etiolate”, which means to stretch out in search of light. Etiolation is both unhealthy for the plant and unsightly.
My Haworthia greenhouse (the term “greenhouse” being used quite loosely) consists of a clear polycarbonate roof, with two layers of 40% black shade-cloth directly under it. I find a single layer of 40% provides far too little shading, especially in summer, and I tested a single layer of 80% and found it does not let enough light through. The sides of the greenhouse are covered by a single layer of 40% shade-cloth as it is positioned in such a way that sunlight does not reach my Haworthia from the sides.
The above also helps with the second important overlooked factor: airflow. Again, one must consider how the plants grow in habitat, and they are most definitely not growing in an enclosed space surrounded by plastic or glass! Some plants, such as Haworthia marxii, will not survive without strong airflow. This species is even absent in otherwise suitable habitat in areas where nearby slopes block wind.
The Haworthia greenhouse at Living Desert Plants
I only cover one side of the greenhouse with plastic to prevent rain from interfering with my watering schedule, and leave the other sides open to facilitate good airflow. If you are growing in an enclosed greenhouse, a large fan to keep air moving and often opening up the doors or windows to let fresh air in are definite requirements.
The most important factor when considering a potting mix for Haworthia is drainage. Haworthia do not tolerate mixes that remain moist for periods longer than 3-4 days. Ideally, you would want a mix that is wet for one day, somewhat moist for two days, and completely dry by the fourth or fifth day at the latest. These plants are prone to root rot, so a gritty soil mix with lots drainage and room for the roots to breathe and grow is ideal.
My personal favourite “mix” to use is a 50:50 mix of small grade akadama and pumice from Bonsai Tree. The porousness of the pumice keeps the soil somewhat moist for a time, while allowing fast drainage. This porousness also allows for good nutrient retention after fertilizing. I prefer the small grade of this mix for general growing, though the fine grade is excellent for encouraging plants that have lost their roots to regrow them. Lastly, I am testing mixes of Akadama, pumice and crushed LECA. For cheaper plants, I use 1/3rd crushed LECA and 2/3rd equal parts peat, pine bark and coarse crushed silica sand.
My two mixtures. Top: Ibaraki Akadama and crushed LECA. Above, professional bonsai mix and crushed LECA
Now, in what kind of pot do you put your mix in? For adult plants, deeper containers are better. Haworthia roots prefer growing downwards rather than horizontally, and some species such as Haworthia truncata can grow thick, tuberous roots, which would push it out of the pot if it was too shallow. To use a plastic or clay pot is a personal choice. I prefer uniformity, and because I have hundreds of plants and need to use my space efficiently, I only use 10cm square black pots or 12cm octagonal green pots. Rounded clay pots are heavier, and take up a lot more space.
The two types of pots I prefer for my Haworthia
Generally, my rule for Haworthia (and all succulents) is “less is more”. My watering schedule is once per week during summer, and once every second week in winter. If you feel you want to water more often, you can wait until the soil mix has been completely dry for 2 days before watering again.
I am in a relatively unpolluted area of the Western Cape (just outside Stellenbosch), so I only use untreated rainwater. Personally, I have picked up a noticeable betterment in plant health with this rainwater over using tap-water. Though this is purely speculative, I suspect the pH is at a good level, and that combined with a lack of chlorine boosts the plant growth. According to the work of Roberts and Burleigh (2010), one wants a pH level of 5.0-5.5 for optimal succulent growth.
Fertilizing your plants is also something one needs to keep in mind and is often neglected. SeaGro is a general plant fertilizer that can be used, and Pokon has a specifically formulated succulent fertilizer also available. Both brands work well. In addition, Roberts and Burleigh suggest supplementing with a weak Ammonium sulfate for the best coloration and growth*.
Harry Lewis is a qualified nature conservationist, with a National Diploma in Nature Conservation from Cape Peninsula University of Technology, and an Advanced Diploma in the same field from the University of South Africa. Between 2015 and 2018, Harry worked with large carnivores, such as lions and leopards, but has now moved back to his hometown of Stellenbosch. He has always had a passion for everything nature, including succulents, and now runs Living Desert Plants, a small succulent nursery, from his home. He specializes in growing Haworthia, but also stocks a wide variety of mostly indigenous succulents.
To contact Harry Lewis you can call him on 0741951144, email harryLivingDesert(at)gmail.com and follow him here: www.facebook.com/LivingDesertPlants/
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*Roberts, E & Burleigh, M. 2010. Ammonium Nitrogen and Acidic Water for Xerophytic Plant Growth. Cactus and Succulent Journal 82 (4).