What is better for plantar fasciitis, putting heat or cold?

Cold : Ice it until inflammation dies down. Icing causing vasoconstriction, or narrowing of the blood vessels, which in turn decreases the blood supply and the swelling. Once this is accomplished contrast bathing in warm and cold baths really help.

Cold.: For acute pain, ice is better. For chronic plantar fasciitis ice is probably better. Heat can be used in certain situations, but its better as part of a supervised physical therapy program.