Lithops growing


Lithops are natives in a very big range in South Africa and Namibia with one or two exceptions in Botswana. This area has different climate zones which mean different rainfall regimes. The most easterly growing Lithops lesliei receives 1000 mm a year. Most other species have to deal with 125-300 mm a year, The most western Lithops (L. ruschiorum and L. optica do not receive rain for years and have to survive on fog from the ocean.
In most of the region the rain falls in the summer period, only L. comptonii grows in a region with winter rain. Fortunately the plants are opportunistic growers and can be adapted to a greenhouse or windowsill in Western Europe by watering on the right times.

kaartjeThe temperature regime on Lithops growing patches differs also. This is partly due to the difference in the altitude of the growing area (0 - 2500 m) but also the ocean has an effect. On the hottest growing areas a temperature of 35C (up to 40C) is normal. The night temperature however is 10-15 C. In the high mountain regions do not match these high temperatures. Even in midsummer the night temperature can fall to below 0 C. In the winter the temperatures are substantially lower and almost everywhere there is frost possible in the night (probably with exceptions very close to the ocean) In general it is not so "tropical" as we think. Heating in winter is in general only needed to keep the greenhouse free of frost as long as the plants are in absolutely dry substrate.
Do not be surprised when you water accidentally in winter because your plant will swallow up readily even when there is low temperature and no light. The consequences come later which mostly ends in a lithops pudding. The most important thing is ventilation both summer and winter and keeping the temperature down in summer to prevent scorch. Most important in summer is ample ventilation and sometimes even shading.


Substrate

In nature Lithops grows on a wide variety of soils but all these soils are dominantly mineral. pH, grain size and structure of the soils can be very different. If there is a common character then it could be that water drainage is perfect. In culture a substrate with a neutral to light acidic works. In principle Lithops can grow on anything but to keep the plants over a long time in cultivation than a mineral substrate the best option. Mineral in the sense that it does not the black compost which is sold in garden centers as potting soil or “Cactus soil” These types of soils contain the water to long and are due the not fully composted material a source of hazards like Sciara flies and fungi. The only organic compost which can be used is salt free (check!!) “Coco peat” which can be mixed in with the mineral component up to 10%. A lot of European growers use “Bims” also known under the name “”Flugsand”. This is a volcanic material of light weight and good water retention capabilities (Not to long/not to short). I use this myself for all my plants. I know that in some countries natural mineral sources are available but I have no experience with them. In all cases make sure to avoid the fraction < 1 mm. This material tends to stick together and form a layer of “cement”. Most of the time I use a sieve to take out the fine particles

Water

Here I will be short: Use rainwater as this is lightly acidic and does not contain unwanted minerals. When tab water is your only option there are 2 options: you can re pot more often (Every year depending on the quality of the water) or you can acidify the water slightly but this is a problem without a decent pH measurement system. Rainwater prevents a lot of problems.


Pots and dishes
Lithops have a taproot and for this reason we have to use rather deep pots. For adult plants think at least 10 cm. Because they love to grow together it is an advantage to have some plants in the same pot. Preferably from the same species, in that case the watering of the plants is the same. It is however possible to create a Lithops landscape with different species in a large bowl which can look very nice. In this case use the less sensitive species like Lithops hookeri/lesliei/salicola/aucampiae.
All pots or bowls must have ample drainage holes to avoid standing water after watering. The discussion plastic versus clay is in my part of the world a historical discussion. Plastic is the way to go.
Re potting is depending on the size of the pot/bowl/dish. The bigger the longer the plants can stay in the same pot. It also depends on the quality of the water which I explained above. The best thing to do is watch the plants; as long as they grow and flower they can stay. Make sure not to use to big pots. An adult Lithops single or double head has ample space in a 7 cm pot.
Report plants always in dry substrate. Remove all fine roots and shorten the taproot to two-thirds of the original length. There should be no watering for at least 2 weeks even in the middle of the growing season when you transplant in high spring or summer keep the re potted plants under light cover to prevent burning. I always transplant in February/March. This means the plants can go back on their spots immediately. A very fine trick to transplant lithops in bims you can see on this YouTube film:

 https://www.youtube.com/watch?v=RFk86KQbXfA.

Her blog also gives info on how to grow on windowsills
.
C 182Lithops karasmontana var.tischeri C 182Lithops gracilidelineata C 309 C 309

Small nasty bugs and fungi

Lithops in general do not have many plagues. Mealy bugs and root mealy bugs sometimes attack our plants but can be handled with a yearly treatment with a systemic insecticide when necessary. Do not spray but water in thoroughly in the soil. In a small collection a mixture of spirit and soap kills the using a paintbrush you can kill all critters you see. In case of a real problem: take the plant out of the pot cut down the roots as you do with re potting and wash the plant thoroughly with 50 C water under the tap.

There is one problem which cannot be solved; it is called “Sudden Death”. The plant starts to be soft and very fast turns slimy and starts to smell very badly. I reduced this happening by using only Bims and no organic matter in the substrate. When this happens the only solution is to get rid of the plant as fast as possible. After that, take a deep breath and continue to admire your other plants. Fortunately it does not happen very often.
Species choice
Start off with species with a somewhat bigger tolerance to beginners mistakes Like Lithops aucampiae/lesliei/hookeri/karasmontana. Some of the “cultivars” can be difficult but some are easy; especially the cultivars from Lithops lesliei. The real difficult things are the most southern species Lithops ruschiorum and Lithops vallis-mariae. There are reasons why seed is rare to find from these species. Lithops viridis/comptonii divergens are also not the easiest to grow.

Lithops, a full growing year

In short the Lithops growing season can be divided in two parts

            

  • November to mid April is the regeneration season. In this period, the new leave pair is formed at the expense of the existing pair of leaves. No watering at all.
  • April until September/October, The growing season. During this period the plant grows and the bud will develop and finally the flower will open. The end of this period will end depending the species. Lithops truncatella will flower first starting in August followed with the yellow flowering species. The white flowering species end the season in October. An exception is Lithops optica which for me flowers in December.

 

December-March
Plants are in regeneration. In the greenhouse frost resistance and no watering. On the window sill a little spray at temperatures above 15C occasionally.
April
The plants whose old leaf pairs are dried out can be given a first tentative watering. Wait with watering untill the old leaves are really dried off. Plants which have seen no sun all winter need some sun protection at first.
May- June
Key growth months for most lithops due to the fairly cool nights. You can now water thoroughly and fertilize
July-August
The hottest months. Many Lithops will take a break at high (night) temperature. Careful watering only when the substrate is dry. First flowering of Lithops pseudotruncatella.
Sept-October
Some late flowering species need a little watering but keep in mind that the pots must be completely dry at the end of the month.
November
Start rest and regeneration period. Completely stop watering.


With this information it must be possible to grow your Lithops. As a last help the following statements:

1

When in doubt never water your lithops. They die when to wet but the never die when to dry.

2

You never have enough Lithops. There will always be a species or cultivar that you want (Greed is sometimes Good).