Beginning in 1869, in his Barren Hill Nursery in Nevada City, Gillet cultivated his own imported scion wood and home-grown nursery stock, experimented with grafting and hybridizing, and continually wrote articles on horticulture and his plant selections, while remaining active in Nevada City civic affairs.
[1] Publishing his own nursery catalog for 37 years and advertising widely, he sold his walnuts, filberts (hazelnuts), chestnuts, prunes, figs, strawberries, grapes, peaches, cherries, citrus and dozens of other fruit and nut varieties throughout California and the Pacific Northwest.
Published the day after Gillet died, a Grass Valley Morning Union newspaper article stated he was born in Roucheford [sic] — probably Rochefort — a port town in southwestern France several miles up the river Charente from the Atlantic Ocean.
At age 16, in 1851, he reputedly spent time at a naval school in Rochefort and made several trans-Atlantic crossings working in the shipping industry.
In 1858, Gillet was a barber in San Jose, California, where French orchardists were establishing large fruit and nut farms.
As young men, the Ducray brothers had quickly made money in mining interests, and then established large, mostly self-sufficient French-style farms at the edge of Nevada City.
Gillet admired Jean-Baptiste Ducray's idyllic 35-acre farm of fruit and nut trees, grape vines, beehives and roses, which had been reclaimed from land mine-stripped to bedrock.
In either the fall of 1869 or August 1870, Gillet purchased with $250 in gold coin 16 acres of land just outside town and started establishing a farm and plant nursery.
While friends cast doubt on his success as a nurseryman, Gillet built a house and established his Barren Hill Nursery while continuing to run the barbershop.
Gillet then spent $3,000 ($49,180 in 2011, adjusting for inflation) on a large order of walnut, filbert, chestnut, mulberry, prune, and fig trees from France.
He risked his personal wealth that his imported scion wood and nursery stock would arrive alive, and would not fail to grow in Nevada County.
From at least the late 1860s, he also persistently championed domestic sericulture and promoted planting mulberry trees as hosts for silkworms, despite little evidence it was economically viable in the United States.
Gillet's advertisements and writings in horticultural journals, such as the popular weekly Pacific Rural Press (published in San Francisco), established his reputation for offering superior French varieties of fruit and nut trees.
At a time when most California fruit was consumed fresh, dried and canned dessert prunes were a popular, expensive import from France.
Gillet competed with John Rock, another well-known nurseryman in Niles (Fremont), to market hardier prune trees that produced very large fruit.
[7] Gillet's last and most enduring plant introduction was in 1885, when he sold a large quantity of filbert (hazelnut) stock to orchardists in Oregon's Willamette Valley.
The "Barcelona" variety remains the most widely planted in Oregon,[8] which today produces 98 percent of the filbert crop in the United States.
The 1897-98 biennial report of the California State Board of Horticulture comparatively evaluated Gillet's "Clairac Mammoth"/"Imperial Epineuse" prune with Burbank's "Sugar."
"[10] Besides tending his nursery and gardens, Gillet experimented with wine making, did book binding and wrote essays and columns about horticulture, astronomy, navigation, and California Indians.
Possibly due to his admiration of abolitionists Samuel and Julia Ward Howe, Gillet was among the few whites who, in the Reconstruction Era, publicly supported equal rights for Nevada County's few African-Americans — some of whom were former slaves.