Is there such a thing as a "too hot" climate for mesembs? I mean, being in the Philippines which doesn’t have marked seasonal temperature variations (temperatures here rarely fall below 26 degrees C/79 degrees F year round, so you could say things range from hot, to real hot haha), is it right to assume that the plant’s natural growing cycles will respond in a rather unnatural way? People I know who have experience growing these plants (just a handful, and they mostly grew or tried Lithops) often say the plants simply grow year long, “bypassing” the usual winter/summer dormancies (which in my opinion would make them rather short lived). I gather dormancy is mostly induced by colder or hotter than normal temperatures (in which case, the excessively hot summer temps here will probably make them dormant). This is all speculation though, for I have yet to get my hands on a plant or two. Also, I’m curious as to how seeds would respond with minimal day and night temperature variations when germinating. I do plan to purchase a batch by the end of the year, and attempt to grow them.
Ron
Growing Lithops and Other Difficult Mesembs
Mesembs are generally not well adapted to tropical climates. The ones which are adapted to grow during summer with considerable heat still require cool nights and will be sluggish or even completely dormant if nights are too hot. Those which are adapted to grow during winter will suffer if it is too warm during their growing period. Most species take their seasonal cues from the length of the night and may become confused without strong variations.
You will have to learn your plants behaviour in your climate. This may be growing during your dry seasons with cooler nights and more sun, and dormant during your wet seasons. Even many of the summer growing mesembs are from high altitude climates and will grow best in cooler conditions. Relatively few will thrive with extreme heat even if you give lots of water. Although your days probably don't qualify as extreme heat, mesembs are from arid climates and nights that stay above 20C will make them sleepy or worse. Other growers in tropical areas report that most mesembs are much easier in locations with cooling breezes or some altitude.
You will also have to more fully understand the "dormancies" of mesembs. Calling Lithops dormant in winter is not strictly true. They are quite happily growing away, its just that the growth is devoted to the new leaves and not visible from the outside until it suddenly appears in spring. Since they require no water at this time in cool temperate climates it is fashionable to call them dormant, but they do require a little winter water in warmer climates. Lithops growth may effectively cease in very cold or very dark conditions, but growth equally ceases during very hot conditions such as a tropical summer.
You will have to learn your plants behaviour in your climate. This may be growing during your dry seasons with cooler nights and more sun, and dormant during your wet seasons. Even many of the summer growing mesembs are from high altitude climates and will grow best in cooler conditions. Relatively few will thrive with extreme heat even if you give lots of water. Although your days probably don't qualify as extreme heat, mesembs are from arid climates and nights that stay above 20C will make them sleepy or worse. Other growers in tropical areas report that most mesembs are much easier in locations with cooling breezes or some altitude.
You will also have to more fully understand the "dormancies" of mesembs. Calling Lithops dormant in winter is not strictly true. They are quite happily growing away, its just that the growth is devoted to the new leaves and not visible from the outside until it suddenly appears in spring. Since they require no water at this time in cool temperate climates it is fashionable to call them dormant, but they do require a little winter water in warmer climates. Lithops growth may effectively cease in very cold or very dark conditions, but growth equally ceases during very hot conditions such as a tropical summer.
--ian
I see. It's only recently that I've started keeping track of daytime/nighttime temps here, and I've also been doing a lot of thinking and planning on how to be able to provide a nice, and close to optimal growing environment for my wards. I grow most of my stuff in the countryside anyway, where daytime and nighttime temps can vary a little more than it does in the city, and where it's not always that humid. That said, maybe I should bug my dad more to allow me get or have a shade house, especially for the monsoon rains. Then maybe I can really start with mesembs or the other more difficult types. Thanks guys. 
There's some nice colours there!
I think my best bet is to try out a mix of soil, cat litter(or something similar) and sand and see if it works out. If not, I'll have to change it. I only recently got the plants that I have now so I'm only at the beginning. Hopefully, it all works out. The info in this thread is quite helpful, thanks.
I think my best bet is to try out a mix of soil, cat litter(or something similar) and sand and see if it works out. If not, I'll have to change it. I only recently got the plants that I have now so I'm only at the beginning. Hopefully, it all works out. The info in this thread is quite helpful, thanks.
A terrific article, Craig! Thank you!
(I also got a kick of reading you and Ian going back and forth - nice to see the interactions and issues of the "pros")
When you said your suggested mix is 3/4 sand and 1/4 soil, do you mean sterilized garden soil or a cactus mix or a regular potting soil?
Also, do your amazing photos show the actual soil mix or do you use a top dressing? Maybe I could get some comments about top dressing. Personally, I don't use a top dressing, but I also have to be careful of crusting.
Shmuel
(I also got a kick of reading you and Ian going back and forth - nice to see the interactions and issues of the "pros")
When you said your suggested mix is 3/4 sand and 1/4 soil, do you mean sterilized garden soil or a cactus mix or a regular potting soil?
Also, do your amazing photos show the actual soil mix or do you use a top dressing? Maybe I could get some comments about top dressing. Personally, I don't use a top dressing, but I also have to be careful of crusting.
Shmuel
Amazing plants, amazing form, amazing flowers...
Amazing cacti!
Amazing cacti!
I don't bother with winter lights for Lithops. They're perfectly happy to spend 4 months dry without much light, and you probably don't have intense enough light to do much good anyway.
Your Lithops are rotting (duhhh, you knew that!). They are probably grown too soft, too tall, too much water, not enough light. Probably also the soil is not good, too much organic material. So the Lithops rot easily. Probably only a few will die, but don't water them at all now. Grow them harder with less water, gritty mineral soil, and plenty of sun, and they are really quite tough.
To answer your question, I don't water Lithops from about now until about April. Some of them haven't been watered since the start of September already. Small seedling might get watered once or twice over winter, or maybe earlier in spring. Late flowering types like L. optica 'Rubra' might get watered in November if they are showing buds.
Your Lithops are rotting (duhhh, you knew that!). They are probably grown too soft, too tall, too much water, not enough light. Probably also the soil is not good, too much organic material. So the Lithops rot easily. Probably only a few will die, but don't water them at all now. Grow them harder with less water, gritty mineral soil, and plenty of sun, and they are really quite tough.
To answer your question, I don't water Lithops from about now until about April. Some of them haven't been watered since the start of September already. Small seedling might get watered once or twice over winter, or maybe earlier in spring. Late flowering types like L. optica 'Rubra' might get watered in November if they are showing buds.
--ian
It's my understanding that there's numerous species of Lithops and therefore the requirements vary from species to species. What do you know about L.optica, I've recently got one of these? What I do know that this species comes from an area that has winter rain fall but information on these is quite scarce.
Lithops optica comes from an area with no rain. More accurately, rain can occur at any time of year but is so rare that a year can go by with none at all. Average rainfall is less than an inch annually, although over an inch may fall in one day in the rare storms. The vast majority of moisture comes as condensation from fog and dew. L. optica hugs the coast and temperatures are nearly identical year round. Summer is a time of slightly stronger sun and higher winds, so harsher for the plants for those reasons, although it is also more humid and foggier.What I do know that this species comes from an area that has winter rain fall but information on these is quite scarce.
All this is near irrelevant in cultivation. L. optica can be treated just like every other Lithops and I encourage you to start this way. In most climates, this means a period completely dry over winter, watering in spring and autumn, and water in summer depending on the conditions. If you are already an expert Lithops grower then you could experiment with different ways to treat different species. L. optica flowers right at the end of the Lithops flowering season, into December and even January in the northern hemisphere. It also likes to hang onto its leaves in spring, and not just because it is watered later in autumn. The northernmost forms are the most extreme in these respects, and L. optica 'Rubra' is characteristic of the most extreme northern forms. More southerly forms are much more standard in behaviour and I haven't found any benefit to treating them different from any other Lithops.
You might well find L. optica difficult unless you are in a climate with strong sun or you can gain extra intensity and lower humidity in a greenhouse. Always provide good air movement because Lithops in strong sun scorch easily. Actually they don't so much scorch as cook from the inside and the first thing you notice is that they are dead
--ian
Thanx for thatiann wrote:Lithops optica comes from an area with no rain. More accurately, rain can occur at any time of year but is so rare that a year can go by with none at all. Average rainfall is less than an inch annually, although over an inch may fall in one day in the rare storms. The vast majority of moisture comes as condensation from fog and dew. L. optica hugs the coast and temperatures are nearly identical year round. Summer is a time of slightly stronger sun and higher winds, so harsher for the plants for those reasons, although it is also more humid and foggier.What I do know that this species comes from an area that has winter rain fall but information on these is quite scarce.
All this is near irrelevant in cultivation. L. optica can be treated just like every other Lithops and I encourage you to start this way. In most climates, this means a period completely dry over winter, watering in spring and autumn, and water in summer depending on the conditions. If you are already an expert Lithops grower then you could experiment with different ways to treat different species. L. optica flowers right at the end of the Lithops flowering season, into December and even January in the northern hemisphere. It also likes to hang onto its leaves in spring, and not just because it is watered later in autumn. The northernmost forms are the most extreme in these respects, and L. optica 'Rubra' is characteristic of the most extreme northern forms. More southerly forms are much more standard in behaviour and I haven't found any benefit to treating them different from any other Lithops.
You might well find L. optica difficult unless you are in a climate with strong sun or you can gain extra intensity and lower humidity in a greenhouse. Always provide good air movement because Lithops in strong sun scorch easily. Actually they don't so much scorch as cook from the inside and the first thing you notice is that they are dead
I shouldn't have to much trouble my summers get really hot and winters quite cold but without snow