While propagating from leaves is more difficult and slower than from offsets, this is a useful technique for Haworthias that don’t (often) make offsets. Besides, regular care like offset division can also result in some removed leaves. They can also be reused for making new plants.
Leaf propagation has the same prerequisite of temperature with rooting as roots will develop from leaves. While leaves in any conditions have chances to be propagated successfully, a healthy and fleshy leaf from an actively growing plant yields the best result. To take out a leave, use a sterilized knife to make cuts on the stem, along both edges of the leaf base (where the leaf attaches to the stem). The cuts can be a bit deep as the wounds will heal quickly. Hold the leaf, put a force toward the stem and slowly shake the leaf sideways to tear it apart. It is important to retain some white stem issues on the leaf base because the issue will become the growing points of new roots and pups. After that, treat the wounds on the leaf and the mother plant.
After calluses have developed on the wound, insert the base part (5~10 mm) of a leaf into a rooting medium. Keep the container in a bright place without direct sunlight, and water it in a reduced frequency as mature plants because the rooting medium retains moisture longer. Roots will appear in weeks and new plants often take a longer time to develop.