Succulents can reproduce in a multitude of ways: Offsets, seeds, stem cuttings, and leaf propagation. "Succulent" is a description of a plant's characteristics and is not a plant family. The term embodies thousands of plants that are not necessarily closely related, so not all succulents have each of these methods available. For Sempervivums (as mentioned in the previous post), producing offsets is one of its primary means of reproduction. On the other hand, leaf propagation rarely works. For Echeverias, it is impossible to generalize because there are more than 200 species, but leaf propagation usually is a viable method along with all the others.
Leaf propagation often occurs without any intervention from humans. A leaf gets knocked off the plant, and a few months later it has roots in the ground and tiny leaves extending into the air. There may be hundreds of YouTube videos devoted to leaf propagation, some of which imply that it is a foolproof process. Not all of attempts will work, but a lot of them will. Everyone has their favorite method, whether it is just throwing the leaves into a box and forgetting about them for a while, or meticulously arranging them on a thin bed of soil and misting them methodically. I fall somewhere in between.
The past few months I've been putting the leaves in a plastic tray on a bit of soil and placing it in an east-facing window inside the house, temperature 60-70 and 35% humidity. I decided to class things up just a little bit and replace the plastic trays with two stoneware bowls, nine-inches in diamater and 1.75 inches deep. I got these bowls with matching saucers/plates at Goodwill for less than $6. Originally they were a Target product. The bowls are a bit too shallow for mature succulents (3 to 6 inches is recommended), but they should work for propagation.
Using a diamond-tipped drill, in one of the bowls I drilled three holes and covered them with drywall mesh to keep soil from falling out. I'm using this bowl for leaves which have developed roots and leaves. The second bowl I left intact and will use it for new leaves which have shown few signs of life yet. The second bowl doesn't need drainage because the leaves don't need any water at this stage. (And drilling holes in stoneware is a tedious process.) If they are developing roots and little leaves, they are drawing upon the nutrition and water reserves inside the original leaf. If the propagation is successful in producing a new plant, the original leaf dries up and falls off. That is when the plant needs water.
Above the drilled bowl is the other saucer and bowl:
Filled with succulent soil and moved to its final location in the east-facing window inside the house, the bowl on the right contains at least 15 plants with roots and leaves. The big Jade leaves just have roots, but I put them in that bowl because there was some room. The bowl on the left doesn't have any little plants, but many of the leaves do have roots. (BTW, in the background of this image are three plants that have grown from cuttings. But that's another story.)
This plant has been my most successful leaf propagation to date. It is now about an inch and a quarter wide, 3/4ths of an inch high. I believe it came from a leaf I stole from my nephew in Texas about 14 weeks ago. The original leaf has shriveled up and fallen away. It is not a quick process, but with some patience (or neglect), a fallen leaf can turn into a new plant. It is hard to pin down how long it takes to get a fully mature plant, but it could be years not months in many cases.
There are some important caveats about obtaining leaves for propagation. The leaf must be removed cleanly from the plant; a leaf fragment will not work. Do not use a scissors or knife; twist and pull the leaf to remove it. With my Pachyphytums, the leaves fall off (too) easily. With some big Echeverias, I have found that getting an intact leaf is a challenge. The leaf should be mature but not too old.
Today at the greenhouse: I have an Echeveria Purpusorum (The Next Gardener) that has had a flower stalk for quite some time. Some enthusiasts remove flower stalks when they develop because they change the look of the plant, and because the buds can attract aphids. I can attest that the latter is true. Rather than chop off the stalk and be done with it, I spray with soap every few days. They haven't attacked any other part of the plant.
Another plant developing a stalk is my Echeveria 'Neon Breakers' (Walmart). It developed in a matter of days, then seemed to be drooping, but I watered the plant and the stalk has perked up. We will see what develops. Hopefully not aphids.
