One man, his agricultural estate and business illustrate the diversity of Napa County agriculture and its allied businesses that existed only a few generations ago. He was William Watt, the owner of Napa’s Longwood ranch and Ambrosia creamery, circa 1912.

In 1906, the 26-year-old Watt arrived in Napa and immediately purchased the north Napa ranch. This Marin County native and Stanford graduate bought the creamery three years later.

Regarding the creamery, it was a processing and manufacturing plant once located south of Third Street, along Soscol Avenue and the eastern bank of the Napa river. Originally built as an ice cream factory, Watt had the complex refitted and expanded to increase its capacity and product lines. In addition to ice cream production, the remodeled Ambrosia included a large cold storage warehouse and ice making facility. Within the creamery operation, cream from local and regional dairies was turned into butter or ice cream.

Napa County once had hundreds of small to large dairies dotting its countryside. Ambrosia had a fleet of vehicles that traveled a three county area to pick up eggs and cream. At the Ambrosia facility the eggs were graded, packaged and shipped to regional markets. With the cream, Ambrosia manufactured 3,000 pounds of butter per day.

As for the original and once exclusive product of Ambrosia Creamery—ice cream, about 4,000 gallons of the frozen dairy treat was produced during the summer months. That ice cream was shipped throughout the entire West Coast. It was also shipped to China within special cold storage compartments of Pacific Mail ships.

Watt prided himself on the cleanliness and efficiency of his modern plant and most especially, manufacturing the finest quality products possible. Tom Gregory, author of “History of Solano and Napa Counties, California,” added, “The highest grade of butter is produced and the superior quality of the output causes a steady demand at profitable prices.”

Gregory continued, “No firm in the west has a higher reputation than this for the quality of its ice-cream and butter and the reputation has been secured deservedly for the utmost care has been maintained in the factory to secure products of the finest grades.”

Watt’s attention to detail and zeal for only the best extended to his home and ranch. His Longwood estate and residence was already considered historically significant in 1912. It had once been a Vallejo family rancho. Located about three miles north of downtown Napa, the Longwood adobe would eventually burn down decades later.

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Gregory continued, “While the house, adobe, itself still stands (in 1912), all else is changed. The environment bespeaks the prosperity of the twentieth century.” He added, “Notwithstanding his interests in town, he (Watt) has established a home on the place and has maintained supervision of that tract of two hundred and fifty acres comprising the estate.”

Watt allowed only the best livestock of the purest bloodlines to be raised and kept at his ranch. That Longwood livestock consisted primarily of horses and hogs.

Watt’s quest for the best also influenced his orchard and garden. The fruit harvested from his 35-acre prune orchard—which yielded about 70 tons of fruit annually—was sorted by hand. Only the best Longwood prunes were meticulously dried and packaged for and then shipped to high-end markets.

Gregory continued, “Of late, he (Watt) has entered extensively into market gardening, irrigating by means of a pumping plant and making a specialty of cabbage, lettuce, cauliflower and potatoes, devoting about sixty acres to this industry.” Gregory added, “No finer ranch is to found in the community.”