My 4 dipladenia plants are beautiful, and have been all summer. Now there are long vines coming out of two of them, but not the other two. Have never grown dipladenia before, so I would like to know what these vines are. Thanks
Are you sure you don't have a Mandevilla plant rather than a Dipladenia? Both are similar in almost every way except Mandevillas are an all-out vine and Dipladenia tend to be bushier and their extensions hang instead of climb.
This article may help you determine with some degree of certainty which plant you have: