Doug Dawson has a quick and easy method to grow lithops using red plastic cups. The instructions are as follows:
1. Poke 7 to 8 holes in the bottom of a red plastic cup (a sturdy leather needle will do it).
2. Pour in about 1 inch of sand into the cup.
3. Next, partly fill with normal, slightly moist soil mix. Often I use 2 parts gravel-sand, 1 part desert dirt (not clay!), and 2 parts pumice. Leave about a 3/4-inch space at the top. Carefully wash down the interior upper sides with a spray bottle so that no dust is present (see footnote below).
4. Fill top with about 1/2-inch of sterilized, finer soil mix. I usually wet the sterile mix a bit before I add it since it may not wet well in the water bath (see #7 below). You can sterilize soil in a toaster oven.
5. Distribute the seeds; methods vary slightly depending on size, shape and type.
6. Sometimes I scatter a dusting of sterile fine sand on the surface.
7. Set the cup in a water bath about 2 to 3 inches deep. Leave in the bath for at least an hour, or overnight for some seeds.
8. Very lightly spray the sandy top to make sure the surface is hydrated.
9. Place a 2-liter plastic soda-bottle top dome on and screw on the cap.
10. Place in appropriate filtered light and temperature, and wait.
Rehydration: If after an appropriate amount of time, none come up, mist the surface gently being careful not to dislodge the seeds. This may be done on several occasions.
Caution: Your red cup with 2-liter bottle top is a closed system and should get no direct sunlight. Don’t cook them!
After a few weeks, eliminate the screw-on cap. Sprinkle with fine sterile gravel, mist, and place clear dome back on without the cap. In a few months, remove the dome completely and add more top dressing. Keep seedlings moist, not soggy.
Footnote: After step 3, to make things go faster, instead of step 7 and before the top is filled with sterile soil (step 4), you can go to the sink and use a very slow narrow stream of water on the surface and let it soak in; continue till it runs out the bottom. Let it rest for a few minutes. Wash down the sides again. Then proceed to step 4 and of course skip step 7.
The seeds sprout within 3 to 14 days, depending on the temperature, location, and the age of the seeds. Individual seed size is very tiny, certainly less than 1/20 the size of a sesame seed. They prefer to sprout where the nights are no cooler than 50 degrees.
To learn more about lithops, see: Lithops: Tiny Treasures of the Plant World.
Doug Dawson is a retired mathematician who travels to Africa each year to study lithops and other succulents.