South African Haworthia and Mesembryanthemum succulent plants for home cultivation
This article discusses the cultivation of succulent plants, specifically focusing on the Haworthia and Mesembryanthemum genera from South Africa. Detailed information is provided below.
South Africa, located in the southern part of the African continent, has a predominantly tropical savannah climate. The region experiences heavy rainfall in the summer and dry conditions in the winter. Due to the influence of the warm Indian Ocean currents and the cold Atlantic Ocean currents, there is a significant climate difference between the east and west coasts of South Africa. The east coast is warm and humid, while the west coast is relatively dry. As a result, the east coast has a greater variety of terrestrial plants compared to other regions, including the Haworthia genus of the Asparagaceae family (also known as the Haworthiopsis genus or Aloeaceae) and the majority of species in the Mesembryanthemum genus of the Aizoaceae family.
Regarding the cultivation of succulent plants, my knowledge is not extensive, and my main area of research is the Haworthia and Mesembryanthemum genera mentioned above. Although I have some understanding of the Agave genus from Mexico, due to climate and environmental factors, Agave plants belong to a different system in terms of cultivation and research, so they will not be discussed further in this article.
Home cultivation is a vague concept of cultivation, limited by the environment and conditions. In a home environment, it is not possible to meet the minute physiological needs of different types of plants through differentiated management. Instead, it is necessary to manage plants from the same origin with relatively large commonalities in a unified manner. For example, the habits of different varieties of winter-growing succulent plants are not significantly different. Although there are many varieties, if you take them seriously, there could be 100 different ways to cultivate 100 different plants. However, if you treat them as if they were the same variety and care for them in the same way, they will grow similarly. This is the concept of vague cultivation. The principle of this concept is to make the most efficient use of the available space and cultivate more plants with the least amount of effort. It is because of this concept of vague cultivation that this article has been written.
I. Definition and characteristics of the home environment
The definition of home cultivation does not mean that any place in your home is a home environment. (Nowadays, there is such a big gap between the rich and the poor that a 500-square-meter garden villa and a pigeon coop with a kitchen and toilet cannot be compared.) To avoid unnecessary disputes and eliminate all factors of disharmony, it is necessary to define what I consider to be a home environment: cultivating in simple environments such as balconies, windowsills, and flower shelves within the living room, without the intervention of artificial drugs, hormones, and other high-tech methods. Outdoor courtyards, terraces, and small greenhouses are not included in this category. However, local use of simple methods for heating, humidification, and other purposes should be considered within the scope of the home environment.
The main characteristics of the home environment are:
1. Indoor and non-open-air environments are the main focus, with overhead shelter and limited direct sunlight. Lighting primarily relies on diffused light. (Don't think that sitting in a recliner on the balcony to bask in the sun is sunbathing. Light passing through a canopy and glass can only be considered as light, not sunlight. You can go to the street to experience it for yourself.)
2. Day and night temperature differences are lower than the theoretical temperature differences in weather forecasts, with moderate high and low temperatures throughout the day, close to the average temperature for that day and location. If this is not the case, I can only assume you live in a pavilion.
3. The space is relatively enclosed, with air circulation and convection relying on artificial intervention. Moisture is prone to accumulate after watering, but under normal conditions, air humidity does not change significantly, with an average daily value lower than the average outdoor air humidity.
4. Most home cultivators are ordinary enthusiasts, not professionals. They may not understand concepts such as hormone levels, the pharmacological effects of pesticides, or the physiological structure of plants. Of course, basic knowledge is still necessary. Otherwise, if you proudly cultivate a Lithops into a long-nosed plant, it will undoubtedly affect the popularity of this article.
II. Physiological characteristics of South African succulent plants
Due to the unique geographical location and peculiar climate of the east coast of South Africa, the native succulent plants in this region have distinctive personalities. Generally speaking, these plants prefer cool temperatures and dislike heat, but they cannot withstand freezing temperatures. They enjoy moisture and dislike dryness, but they do not tolerate waterlogging. They thrive in sunlight and fear shade, but they cannot tolerate excessive exposure to the sun. Ultimately, the most remarkable characteristic is that they not only incorporate these traits but also go against them in an exaggerated manner. Surprisingly, they can still thrive. Of course, achieving this level requires certain preconditions. In most cases, at home, unfortunate events are likely to occur frequently.
1. Physiological characteristics of Haworthia plants
Haworthia plants are winter-growing plants. During the winter months of May to August in South Africa, there is abundant rainfall, which is the peak growing season. Since Haworthia plants are winter-growing, it indicates that they prefer cool temperatures. However, South Africa is in Africa, close to the equator, and its geographical location determines that even in winter, the temperature will not be too low. Taking Cape Town, South Africa as an example, the average winter temperature is around 7 degrees Celsius, and the temperature can briefly rise to around 25 degrees Celsius under sunlight during the day. Occasionally, there may be extreme low temperatures of 2-3 degrees Celsius at night. Overall, this temperature is much more bearable than the winter temperatures in southern cities. Unfortunately, the situation is reversed during the summer months of November to February, when the average temperature is 26 degrees Celsius. Due to the influence of the geographical environment, there are often low temperatures of around 15 degrees Celsius at night. This is what is referred to as a place with warm winters and cool summers. For many plant enthusiasts who have suffered from the climate in southern cities, South Africa would undoubtedly be ranked among the top destinations for immigration.
During the summer in the native region, when rainfall is scarce, most Haworthia plants enter a protective dormant state, and there are very few varieties that continue to grow during this season. With the exception of a few rare highland species, most varieties rely on shortening their stature and partially burying themselves in the soil to resist intense sunlight and moisture evaporation. Fortunately, due to the large day and night temperature differences and the frequent erosion of oceanic water vapor (N-D), water droplets often condense on the plant surfaces at night, providing some moisture to the parched life. This is the reason why native Haworthia plants can survive long periods of water scarcity in the summer.
Haworthia plants belong to the semi-shade-loving category. Of course, semi-shade-loving is a relative term. The semi-shade-loving nature of Haworthia plants does not mean that they should be kept in shaded areas for a long time, but rather refers to the intensity and duration of sunlight exposure. From the photos of native plants, it is evident that Haworthia plants are less abundant and less full-bodied in exposed rock areas, often appearing shriveled and withered. In contrast, there are more Haworthia plants in forest understories and grasslands, suggesting that sunlight is a major influencing factor. Based on experience and relevant literature, it is believed that Haworthia plants require 3-4 hours of moderate to weak sunlight intensity per day, which is what we refer to as semi-shade-loving.
Since Haworthia plants are semi-shade-loving, their water requirements must match accordingly. Logically speaking, if they dislike intense sunlight, they must also dislike water loss. Therefore, continuous moisture supply (G-Y) is essential. In the arid and hot climate of Africa with limited rainfall, it is inevitable that the native region cannot have abundant rainfall throughout the year. This necessitates that plants have the ability to store water. The presence of water storage capabilities also indicates that Haworthia plants have drought resistance. Generally, plants with certain resistance can easily be overwhelmed if provided with excessive amounts of water. This is a consensus and a fundamental principle in this discussion, which does not require proof. Therefore, the final conclusion is that Haworthia plants require water but not excessive amounts of it. In simpler terms, if we categorize water supply into four levels of wet, moist, damp, and dry, Haworthia plants should be supplied with "damp" conditions.
The water storage capabilities of Haworthia plants, as well as the soil texture of the native region (compared to cacti from Mexico), result in the plants having thick, fleshy roots, rather than capillary roots like those of cacti. Fleshy roots require a large amount of oxygen. Unlike capillary roots, the main function of fleshy roots is to store and transport nutrients, acting as a "pipeline." Therefore, the epidermal cells of fleshy roots appear slightly larger and denser, which helps to reinforce their physical structure, equivalent to strengthening the "pipeline" function. However, such tissue often has a slow metabolism, and old cells are not replenished in a timely manner. Dead cells in an oxygen-deprived environment are easily colonized by anaerobic bacteria, leading to root rot. However, the roots of Haworthia plants are not completely different from those of cacti. They share a common tragic characteristic, which is extremely low osmotic pressure. This means that salt from the surrounding soil can easily penetrate into the cellular tissues, causing cell dehydration. We all know how to pickle meat and vegetables. Sprinkle some salt on a piece of fatty meat or a cabbage, and within half an hour, water will seep out. Leeches also dissolve when exposed to salt. This is the principle of osmotic pressure. The low osmotic pressure of Haworthia plant roots, which is related to the water scarcity in the native region, allows for easier absorption of limited water from the surroundings.
2. Physiological characteristics of Mesembryanthemum plants
Lithops and Conophytum, also known as living stones and meat domes, are representative succulent plants from the east coast of South Africa. Unlike the Haworthia genus mentioned earlier, these plants mostly grow in exposed rock areas, exposed to intense sunlight all day, with limited resources. A few millimeters of rainfall each year are enough for them to reproduce joyfully during the breeding season. However, if the heavens open up and provide a few more drops of rain, it often leads to a large number of plants rotting. Essentially, these plants are typical examples of not knowing when they have enough, thriving in harsher environments compared to most other plants.
Compared to Haworthia plants, Lithops and Conophytum plants are full-sun-loving and have semi-woody taproots with low water requirements. (For example, some varieties such as Orostachys have an annual rainfall of only a few millimeters in their native region.) These plants have stronger resistance and the ability to withstand external damage compared to Haworthia plants, especially in terms of withstanding low temperatures (approximately able to withstand short periods of -5 degrees Celsius).
The commonality with Haworthia plants is that they are both winter-growing and have low osmotic pressure in their roots.
III. Sunlight and the pursuit of sunlight by South African succulent plants
1. The role of sunlight
As the saying goes, "All things grow with sunlight." Without sunlight, plants can become restless. In ancient times, prisoners were often locked in dungeons to deprive them of the right to bask in the sun, highlighting the importance of sunlight for living organisms.
Compared to animals, plants are more dependent on sunlight. Light helps plants perform photosynthesis and produce nutrients (G-Y) throughout their bodies. Some people may argue that plants have roots, and it is the roots that absorb nutrients (S-Y). I can only say, please refer to your middle school biology textbook. The roots of plants absorb raw materials, which are then transported to the leaves. Through the catalytic action of chlorophyll, carbon dioxide, and sunlight, photosynthesis occurs, ultimately generating sugars that can be utilized by the plants. It is similar to how blood flows through our veins, not rice.
Sunlight refers to natural light with a full spectrum. A full spectrum is the visible light that reflects seven single-color visible lights after passing through a prism. Natural light also includes composite light in invisible bands such as UVA, UVB, and UVC. The visible spectrum in sunlight, including red, blue light, as well as UVA, UVB, and UVC, plays a major regulatory role in plant growth. There are high-tech red and blue plant growth lamps available in the market, which are said to be effective. However, the cost of using these lamps is likely to be much higher than the price of cultivating plants in most households. It is enough to know that such lamps exist, but don't take it too seriously.
2. Introduction to invisible light in sunlight
UVA, with a wavelength of 320-400 nm, is also known as long-wave black spot effect ultraviolet. It has strong penetrating power and can pass through most transparent materials, damaging the epidermal cells of organisms, promoting cell aging, and causing tanning in humans. This is what women try to prevent both day and night. For succulent plants, this band of light promotes the aging of epidermal cells, making the outer shell hard and thick, less watery in appearance. However, at the same time, the resistance of the plants is enhanced, and their resistance to physical damage from the environment is significantly increased. This is especially important for plants in residential areas with good environments, as exposure to UVA can greatly improve their resistance and survival rate when exposed to wild animals such as birds and squirrels. More importantly, moderately aged epidermal cells can prevent sunburn when exposed to sudden increases in sunlight. Therefore, appropriate and moderate UVA exposure is essential for home cultivation.
UVB, with a wavelength of 275-320 nm, is also known as medium-wave erythema effect ultraviolet. It has moderate penetrating power, with only about 2% reaching the ground after passing through the atmosphere. This band of ultraviolet light helps animals with mineral metabolism and the formation of vitamin D. We actually expose ourselves to UVB when we bask in the sun, hence the name "life ray." For plants, UVB promotes photosynthesis, but its promotion is opposite to that of visible light. From a superficial perspective, it can make plants shorter, allowing them to accumulate more nutrients in the roots and stems, ultimately improving their physique and promoting flowering and fruiting. Without UVB, all plants in the world would become soft and weak, like韭菜秧子. (You can imagine a combination of Lin's physique and Yao Ming's height.) From the perspective of home cultivation of succulent plants, UVB exposure can make plants shorter and more compact, enhancing their appearance and increasing their resistance. The long-nosed plant mentioned earlier is a negative example.
UVC, with a wavelength of 200-275 nm, is also known as short-wave germicidal ultraviolet. Its main function is to kill germs. Excessive exposure can cause cell death, leading to skin cancer in humans and burns and withering in plants. I prefer to call it the germicidal ray. Fortunately, its penetrating power is the weakest and cannot pass through most transparent glass and plastic. Additionally, most of it is absorbed by the ozone layer during its passage through the atmosphere. (Therefore, protecting the ozone layer is crucial...) For home cultivation of succulent plants, due to the general low use of drugs, it is necessary to receive appropriate UVC exposure for the health and sterilization of the plants. This can help kill harmful bacteria on the plant surface or in the surrounding environment and promote the metabolism of epidermal cells, similar to UVA.
3. The pursuit of light by plants
So, what are the characteristics of the pursuit of sunlight by South African succulent plants in a home environment? If you are smart enough, you should have some understanding after reading