Answer: If it's the common Donkey's (or Burro's) Tail, your sedum will respond to tip-pinching by putting on new growth which will evenually set flower buds. A nice by-product of pinching your plant back is that you can root whatever you take off. Just let the pieces dry for a day or two and then poke them into a sandy potting mix. After a while they'll take root and you'll have a whole collection of plants.
Q&A Library Searching Tips