Is Rosemaling Swedish?

In simple terms, no.  Rosemaling is the name of the decorative folk art developed in rural Norway that flourished in the late 1600's through the mid-1800's.

Norwegian rosemaling was very popular in the United States in the1960s through the 1980's, and because of this, the term is more familiar and often mistakenly applied to Swedish folk painting. Sweden's folk painting goes by various, lesser known names, such as kurbitsmålning (or kurbits), dalmålning, and bonadsmålning. While the folk arts may appear to be similar, there are distinct differences; colors, subject matter, and designs can be very different from that of Norwegian rosemaling. 

Go here for more on the History of Rosemaling.

Vesterheim Norwegian-American Museum has a great resource for: What is Rosemaling.