I'm mostly a Brugmansia fan, and propagating is totally different from what I plan to do with my mums. I have a small patio and about 6 or 7 potted mums. Is it true that I can simply remove a twig and plant it, and it will grow roots and prosper?
Thanks for any info on the subject.

Try dividing first. When the new shoots start coming up at the base of the plant, prune out the old stems, water it, then slip it out of the pot. Gently break up the clumps of stems into smaller clumps of 3-4 shoots each--potted plants from the florist often have 3-4 major clumps per pot to break up. Re-pot the divisions separately, water with a root stimulator, and keep them partly shaded until they resume vigorous growth.

A more advanced technique is the semi-hardwood cutting. take a vigorous (but not gigantic) stem and gently bend it several inches below the growing tip. It will naturally break about where the stem is forming its basic woody structure. Make a second cut just below the lowest leaf, pinch off the two lowest leaves, and cut off the growing tip. Dip the lower end of the cutting in rooting hormone--not essential, but a good precaution for beginners--and insert it into a pot of moist sand just deep enough to allow it to stand up securely. Put the pot with several cuttings in a plastic bag to keep the humidity in, and punch a few pin holes in the bag to let oxygen in. Keep the bagged pot in bright, indirect light, and at slightly less than room temperature. After about 3 weeks, new growth should start to appear at the top ends: that is the signal to start hardening off the rooted cuttings. Open the bag for 15-30 minutes twice a day for several days, then gradually increase the exposure over the next 3 weeks, until the cuttings are exposed all the time. Transplant into separate pots, and gradually get them used to the sun exposure of their new home. New shoots should appear at the base of the new plants as well as the tip of the new cutting.

Hope I haven't repeated too much of what you already know! : )

Ingrid.