I've really had great luck with vinca's this year and last. As the cooler weather is coming, I notice some leaves yellow. (I'm guessing it means it wants more iron?) When frost comes, I cut them down, but don't pull them out, even though they are annuals. The following spring (or earlier) they start to sprout again. Also, the ones in my pots, show new sprouts in spring. I transplant them into small containers, till they get to size for planting. They are so hearty, and easy to grow.
