Here is a detailed description of how I propogated a Seven Sisters with 80% success so far. I hope this helps.
1.Collect some of the smaller round transplanting pots that you usually get with annuals in the spring.
2. Put enough mulch in the bottom to provide good drainage.
3.Mix in equal proportions of 1/2 miracle gro or other high quality potting soil, and 1/2 perlite.
The perlite keeps the soil from compacting around new root growth. Put mix in prepared pot only lightly compacting it from the top by hand.
4. take the cuttings as you normally would for propogation, 1/4 inch below a mature node, where leaves have been.
(wounding is optional) 6" sections work the best for me,
and at the top try to cut a good 1/2 to 3/4 inch above another leaf node where you might expect new growth. Leave A leaf or two If you can (It helps.)
Do not let the cuttings dry out.
5. Take A pencil or likewise object and poke a hole into te soil then place what you determine to be the bottom of your cutting gently down into it. water in well with a good root growth stimulator horomone, and press the soil around the top to support the cutting.
6. Mist the cutting, the inside of a large jar,and the top of the siol in the pot.
7. cover with jar, and make sure the Inside of the jar always to appears to be sweating.
8. Keep out of direct summer sunlight during the day, mornings and evenings seem to work well.
9. Water every day, Mist the inside of the jar and water well if the jar appears to be dry.
I have had a lot of good luck with this one.
Good luck.