Here is Dale Marten's method of starting leaves. I hope this will be a help to anyone new to propagating streps from leaves.

Propagation

Cut a 2 1/2" section from base to tip while keeping the leaf and cuttings under water. Leave them under water for about 5 minutes. Then bury each leaf section about 3/4 of an inch deep into a soilless mix lightened with extra perlite and vermiculite. In the warmer seasons you'll see young green leaf tips popping out of the soil in a matter of weeks. In the colder seasons, it can take longer.

Dave