I'm sure there are herbs to help increase blood circulation, however I have found some success with dry skin brushing, concentrating on my legs and feet, as well as massaging them.
Try to not sit with legs bent at the knee any more than necessary, straighten them if possible.
That helps keep the arteries and veins flowing easier. Walking a bit helps your heart pump into your legs as well.
ETA: Japanese Knotweed is recommended for circulation.
Someone also mentioned nitric oxide as being beneficial too. These are both ways of dealing with dwindling circulation which may not be the only reason for cold legs. But that's the best reason my Internist came up with for me.
Post Edited (julymorning) : 11/21/2016 1:24:08 PM (GMT-7)