They will take over the whole neighborhood if you let them.

Interestingly, they have never spread on me. I have one well-behaved Tradescantia, the kind with the light-green/chartreuse foliage. It probably depends on the climate if they spread or not. I live in a very hot dry summer, cold winter climate.

Nel5397 may also have been talking about a different species of Tradescantia. At any rate these are in the spider-wort family and not the iris family.

Looks like one of the Andersoniana group - common spiderwort - which do have a reputaton for being aggressive speaders in the right environment.

The non-spreading chartreuse Tradescantia is probably the cultivar "Sweet Kate" which is well behaved and beautiful. Some others that don't spread wildly in my garden are T. sillamontana and T. pallida.

Susan