Discussion on the cultivation method of Lithops
Let's talk about the content related to the cultivation of Lithops, a discussion among gardening enthusiasts on the cultivation methods of Lithops, which is very useful knowledge worth collecting!
I have been growing Lithops for 20 years, during which I have tried different substrates, temperatures, and shading methods. In the end, I found the method that suits me best, and I will introduce my own cultivation method below. Be aware that this is the method I find most suitable for myself, but it may not be the best everywhere.
Seeding propagation is the main method of Lithops reproduction. Of course, they can also be propagated by cutting roots and dividing the plant, but the division propagation of Lithops is much more difficult than that of Conophytum species. Moreover, most of the divided plants come from large clusters. Given the slow growth and difficulty in dividing the heads of Lithops, large clusters of Lithops are relatively rare and precious (not recommended for division).
Seeding Lithops is not a difficult task. Seeds collected and properly preserved in the previous year are the most suitable for sowing, as fresh seeds often encounter many problems during the germination period (note: this refers to the seeds that have not undergone post-maturation). If stored with seed cases in a dry and dark environment, seeds can still maintain high germination viability even after more than 10 years.
I choose an inorganic medium as the seeding medium. Pure volcanic rock is commonly used for seeding. If you do not have enough volcanic stones, you can also choose sand or other small stones with a diameter between 1-4mm for seeding.
However, be careful not to exceed a pH value of 7 (note: most plants in the Aizoaceae family prefer acidic environments). I do not use any organic mediums such as peat or garden soil for seeding, as they often contain insects or harmful bacteria.
To ensure that the seedlings' roots can penetrate the medium directly rather than creeping on the surface, it is necessary to avoid fine particles and dust in the seeding medium. This is another reason why I do not use garden soil and peat (note: the horticultural community in China prefers peat medium, as it contains suitable organic matter and good aeration, helping plants achieve the best growth rate).
Strict German gardeners prefer to ensure everything is foolproof, and this reason guarantees the extremely high quality of the plants.
Before seeding, we need to disinfect and sterilize the medium to prevent the outbreak of diseases and pests later. I usually use the high-temperature sterilization method, which is to heat the planting material to 200 degrees Celsius and maintain it for an hour (note: due to personal reasons at home, I only soak the medium in potassium permanganate. Friends using a microwave for disinfection should be careful, the medium must be moist to prevent drying and causing spontaneous combustion).
Before seeding, place the disinfected medium into the seeding container, then wet the medium completely with rainwater. You can also use tap water without salt and alkali calcium. After that, sprinkle the seeds on the surface of the moist medium without covering them with soil (note: covering with soil is still a matter of personal preference; I still cover with soil during seeding, but it is not recommended for beginners). Seed at a density of about 10,000 seeds per square meter, which density can achieve a very long period without transplanting. Then cover the seeding container with a transparent film to seal the environment and increase humidity, and place the pot in a shaded area without direct sunlight. Maintain the internal temperature at around 15 degrees, and do not exceed 20 degrees (note: this is the seeding method of this German person, according to our own experience, a temperature of 25 degrees might be a better choice for Lithops seeding).
Seeding on a windowsill (home seeding) generally has better conditions than in a greenhouse. The temperature in greenhouses or greenhouses is too high, and direct sunlight is too strong, while home seeding can bring a good day-night temperature difference, which can also help seeds germinate. After two weeks of闷养 (sealed cultivation), the germination stage can be considered over, and then you can uncover and manage the seedlings with ventilation.
After uncovering the seedlings, it is necessary to spray water multiple times a day for the first few weeks to prevent the surface from drying out. At the same time, gradually increase the light intensity, but during the first year of planting, be sure to avoid full sun during high-temperature, clear weather, as this may bring devastating blows.
Try not to use chemicals, and do not use fertilizers for seedlings under one year old. As the plants grow larger, the intensity and amount of light they receive should also be continuously increased, but do not forget to do shading work during hot, clear weather (the author wrote a sentence: Lithops require shading all their life. I estimate it means that many desert tropical plants survive by depending on certain obstacles around them). If the climate in your area brings good light throughout the year, you won't need to do much shading.
Compared to the long, dark German winters, Lithops may die in less than an hour under the spring sun.
Lithops can grow well under proper shading, and some large nurseries also use shading methods to grow Lithops. Plants grown by this method usually grow faster and are larger but tend to become tall and soft (note: what we call etiolation). Lithops grown under these conditions often have poor color expression. If you compare a large, green Echeveria with a smaller plant that has bright red and black stripes and a yellow epidermis, you will find the huge difference brought by good lighting. This is why I only shade plants when necessary.
Lithops require very little fertilizer. I use a liquid fertilizer with an N:P:K ratio of 8:8:8, applied two to three times during the growing season. Like many gardeners, I have increased the watering frequency and amount for Lithops, but considering safety factors, I recommend not watering during hot summers. And every year from February to March, I completely stop watering (note: I am also confused about this aspect of care. Compared to winter dormancy, many of us start cutting water in December until the following March. And with good ventilation, proper watering in the summer is also fine. This paragraph is for reference only).
I use insecticide on Lithops only once a year during the growing season, a pesticide named Imidachloprid in Germany. Apart from that, I do not use any chemicals unless there is a very serious pest or disease problem.
Except for the seeding stage, Lithops prefer warm days and cool nights (implying that the seeding temperature is low?). In winter, I tried to let Lithops survive without any heating, but there seemed to be some deaths. However, after two nights of minus six degrees Celsius, my Lithops also brought me the surprise of zero loss (probably some experimental samples).
Under sufficient light, Lithops will bloom for the first time three years after planting. Some Lithops may bloom in the first year, but the possibility of them blooming again in the second year is very low. Moreover, it is relatively easy to obtain seeds from flowering plants. If you want to give yourself a surprise, let the little insects help you with the pollination. If you prefer pure breeds, drive the insects out of your garden and use a small brush to pollinate your plants (remember, one brush per variety) (note: I remember once hearing a friend question the pollination of numbered plants abroad, at the time the friend said, "I don't believe that foreigners use one brush per variety," so we should still believe in their methods). Most Lithops can cross-pollinate to obtain hybrid seeds, but the little insects don't care about these...
Lithops planted in small pots need to be repotted every 2-3 years, but those grown in large containers can remain in the same pot for many years without repotting, basically watering by浇灌 (pouring water) rather than 淋灌 (soaking), and allowing the water to flow out from the bottom of the container. Again, I grow my Lithops in pure volcanic stone. When repotting, leave only 2-3 centimeters of the main root, which makes it easier for Lithops to develop roots and allows the roots to grow straighter in the new pot. If the roots of Lithops are too long, they will slowly curve and deform (I don't know if crooked roots have an effect).
You can clean the outer shell of the old plant, but the lower part of the old plant is usually thin and brittle, so it's safer to leave the old skin on the plant, otherwise Lithops can easily fall off the large cluster. If this unfortunate event occurs, immediately place the fallen Lithops in the medium and keep the medium moist, and be sure the temperature is below 15 degrees.
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