His artistic career began in 1915 but was briefly interrupted in 1917, when he spent a year in the United States Navy.
He made his permanent studio in Gloucester, Massachusetts, and became a member of the Cape Ann school of artists.
Although Gruppe is best known for his variety of impressionistic landscapes, he also painted figures and portraits.
His modern style was largely inherited from the French Impressionist Monet.
"Lily Pads", date and location unknown, one of Gruppe's landscapes, attests to Monet's influence; it is similar to some of the paintings in Monet's Water Lilies series.
From 1940-1970, he ran the Gloucester School of Painting at Rocky Neck, on Smith Cove in Gloucester, Massachusetts.
He was the teacher of other famous artists including oil painter Otis Cook of Rockport, Massachusetts, and his work was an influence on Bill Wray, Nathalie Nordstrand, Carl W.
Illig, and other painters.
He sometimes wintered in Naples, Florida, where he painted tropical scenes.