Last year I tried to start African blue basil from stem cuttings in cutting mix and got only one small plant from all of my efforts. This year I put some stems with flowers in water to make a nice, subtle spray of lavender spikes, and left them in the vase for almost 2 weeks. By this time they were sort of bloomed out, so I was about to dump them. But I noticed that the leaves were still not wilting. Hm. Removed them from the water to find most of them were rooting!
Rooting in water usually isn't the best idea, 'cause when you take the cutting out of the water, the new roots tend to clump together. Better if you can root in some kind of rooting medium, like perlite with a little bit of peat moss mixed in, or even potting mix, so the roots can get kind of distributed through the medium. But water it was, so I have potted up 6 rooted cuttings. First I clipped out all of the flowering stems, then I set the cuttings in individual 2" diameter plastic pots, separating the roots as much as I could. Then I set the pots in a small styrofoam tray and covered them with a clear plastic bag. I kept the setup out of the sun.
After 2 days, I have uncovered the plants and 5 of the 6 are OK. The 6th is wilting, and probably won't make it.
The African blue basil parent plant in my community garden is blooming exuberantly and is about 3 feet tall and across. I am suddenly overwhelmed with basil. After years of struggling to grow the stuff, I could now make pesto twice a week if I wanted to. An amazing plant!
In any case, I now have 5 new free plants to plant at the City College garden, where the cold, windy microclimate will probably keep them much smaller, but still bigger than any other basil would be there.
If you would like to read my last summer's SF Chronicle article on African blue basil, you can do so at: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/07/23/HOG7FDQRSK1.DTL&hw=African+blue+basil&sn=001&sc=1000