Lithos, also popularly known as "Living Stones," thrive in low humidity and need infrequent watering and care, making them ideal houseplants. However, you must put them in a well-lit location because they have adapted to intense sunlight in the wild during their evolution and they need a good amount of sunlight – around four to five hours of direct or slightly filtered sunlight during the early part of the day and partial shade during the afternoon. Otherwise, they become slender, elongated and lean to one side to receive more light, or they may lose coloration and the sides of the plant turn greenish; and in some cases, the plants die. In the tropics, the greening of their bodies does not necessarily mean they’re dying, it could simply be the result of local climatic conditions.
Here are more tips for healthy, thriving lithos:
1) They require little or no watering when dormant. Water lightly so that about only the top or 1Ú2 inch or so of the soil is moistened.
2) They begin to flower only when they’re about three to five years old.
3) Without direct sunlight, they grow slender and tall up to two inches in height and new leaves will still come out healthy.
4) Reduce watering as the heat and long days of summer approach.
5) Pots that are about three to five inches deep are recommended to allow the roots adequate room to grow.
6) Make sure that drain holes are provided for the pot. A packaged soil mix for cactus and succulents should have sand added with about two-parts soil mixed with one-part sand.
7) Space the plants at random, poking a hole into the soil to accommodate the taproot and lower portion of the body.
8) Position the plants in the soil so that about 3Ú4 of the height of the plant remains above the soil level to permit it to breathe.
9) Collapse the hole around the taproot by carefully poking a pencil into the soil near the plant. Set a few pebbles between the plants and sprinkle a thin layer of coarse sand (or bird gravel) over the exposed soil.
10) White scar tissue caused by spider mites appears on the surface of the plant.
11) If possible use square pots as they hold a larger volume of medium for any given size.
12) Lithos should be watered from early summer to early autumn (May/June to the end of September) in the northern hemisphere; the Philippines is still a part of this region.
13) Flowers usually appear from late August into autumn. Water is then withdrawn as the weather becomes colder and the outer skin is allowed to shrivel to a papery epidermis before watering commences again in summer.
14) Over-watering and excessive shade often cause the old body not to dry up and wither, but remain on the side of the head/heads of the new generation.
15) Before a new head emerges, part of the old head can be removed with a sharp knife. Don’t do this if you think you will harm the meristem.
16) There is a 63 percent increased heads after flowering and 37 percent increased heads without flowering.
17) Increased nutrients lead to increase in size only, not in the number of heads.
18) Soil type determines the length of time the plant remains wet. The soil must be compact to support the fine root system.
19) In the warm growing season, drench the plant and leave it to dry out completely. Wait two to three days before watering again.
20) In cultivation, they’re grown with the whole stem out of the soil in most cases because we cannot reproduce the high temperature and low humidity of its natural habitat.
21) They prefer an open and free-draining soil mix consisting of compost/peat/potting mix and a high proportion of pumice and stone grit, especially in the upper levels or even a layer of stones on the very top to protect the plant from excess water.
22) Remove old leaves if they can come away easily as they may hide insects or bugs or encourage rotting.
23) If the plant becomes stressed or shriveled excessively, give them a small amount of water.
24) Lithops in habitat won’t stay wet at the roots as they would in a pot, diminishing any possibility of rotting. They’re able to withstand very wet conditions, even being submerged for a few hours or even a day or two, but in their natural habitat they dry quickly. A low-nitrogen slow-release fertilizer can be incorporated into the potting mix, which will release small amounts during watering.
25) In nature, when it rains, it releases seeds, but if no rain is present, seeds can be retained in their capsule for many years.
26) In the Philippines, lithops don’t undergo "aestivation" or dormancy because of our tropical climate. It’s safe to say that watering can be done once a month especially in summer. Our summer heat may prematurely wrinkle lithops so some watering should be done to prevent this from happening. At the same time watering can induce the plants to start sending new meristem and retain their bright colors.
27) In case of mealy bug infestation, treat with soapy water or dab with a Q-tip swab dipped in rubbing alcohol.
28) When watering, soak the compost fully. Remains of old bodies and any flower stems can be carefully removed when they’ve become thoroughly dry. Small scissors and tweezers are useful for this.
29) In South Africa, farmers call them beeskloutjies (cattle hoof) or skaappootjies (sheep hoof).
30) Lithos have an extensive root system, which requires a larger pot than the plant size indicates.
31) In warm growing season (starting March), when the leaves start to shrivel, drench the soil then leave it to dry out completely. Two to three days after it dries out, water again. Stop watering altogether during the cold season (beginning at the end of September), but mist once every two weeks. Once the old leaf pair has withered entirely, resume the watering schedule.
32) Windowpanes can magnify sunlight and should be taken into consideration when assessing the total hours of sunlight. The plants etiolate when they receive too small light, growing high and out of proportion.
33) It’s often useful to feed a few times in summer with a bloom inducing (high phosphorus) plant food at 1/3 strength. This encourages blooming in autumn.
Too much feeding will result in bloated plants. Lithops don’t mind warm climates/temperatures in summer but can burn in direct sunlight.
34) Lithops aren’t difficult to grow once the growing cycle is understood.
35) As the outer covering begins to disappear, it’s not wise to help it along by peeling it off yourself, for the plant underneath could be damaged in the process and the tender skin suffers sunburn, so leave it to nature. Early summer is the time to repot if necessary, but as the plant uses the soil for only three or four months in the year, a lithops may remain in the same pot for several years and come to no harm. Only if it’s a clustering type, repotting in a bigger container may be necessary. Cuttings may also be taken at this time of the year, early summer, by removing a body very carefully, cutting it off below the body with a pair of fine pointed scissors.
Set the cutting in sandy soil and after a week or two slightly dampen the soil. Roots will soon appear and it will also flower later on in the same season, for this is a mature plant and not a seedling. A very sandy soil is necessary:
Half-coarse sand and fine gravel to equal quantities of loam and leaf mould suits them well. When planting, it is important that the roots go down quite straight. After planting, cover the whole surface with fine gravel, thick enough to keep the plant bodies away from the soil. Seedlings are treated in the same way as adults only as they shed their skins more frequently. Water only when they break through them and cease as soon as the body shows signs of shriveling. This happens several times a year, more frequently.
36) Anything organic is dangerous for lithops.
37) When repotting, you may lose a lot of roots but keep the main tap root on each plant intact. Keep them dry for a couple of weeks or until the new leaves come through and the old ones dry up.
38) Any slight damage to its body results in immediate rot.
39) Water only early in the morning when the sun is shining to evaporate excess water fast.