In 1835, he was married to Isabella Pratt Welles (1812–1888), a daughter of Samuel Welles. She was the half sister of . Together, they had nine children, including: • Hollis Hunnewell (1836–1884), who married Louisa Bronson (1843–1890), sister of
Frederic Bronson. • Francis Welles Hunnewell (1838–1917), who married Gertrude Gouverneur Sturgis (1862–1890), daughter of
John Hubbard Sturgis. • Susan Hunnewell (1842–1843), who died in infancy. • Walter W. Hunnewell (1844–1921), who married Jane Appleton Peele (1848–1893), daughter of Jonathan Willard Peele, in 1873. • Isabella Pratt Hunnewell (1849–1934), who married Robert Gould Shaw (1850–1931), cousin of
Robert Gould Shaw. • Jane Welles Hunnewell (1851–1936), who married Francis Williams Sargent (1848–1920), grandparents of Governor
Francis Sargent. He died at home in
Wellesley, Massachusetts, on May 20, 1902, at age 91. Hunnewell was buried in
Mount Auburn Cemetery in
Cambridge, Massachusetts, among his family.
Estate and arboretum ,
topiary section on the shore of Lake Waban,
Wellesley, Massachusetts (1909). Starting in 1870, Hunnewell built country homes adjoining his own for seven of his nine children. These estates and adjacent farmland, with one exception still owned by his descendants, form the
Hunnewell Estates Historic District, which was added to the
National Register of Historic Places in 1988. Both the town of Wellesley (founded 1881) and
Wellesley College (chartered 1870) are named for Hunnewell's estate, "Wellesley", which he named for the family of his wife. The
H. H. Hunnewell estate includes a prominent 1851 house designed by
Arthur Gilman with attached
conservatory and gate lodges of 1865-1866 designed by
Gridley J. F. Bryant, a
pinetum of 325 specimen conifers, a complex of specialty
greenhouses, and the first
topiary garden — the "Italian Garden" — in America, all of which are still standing. The estate is part of the
Hunnewell Estates Historic District, which includes the estates of many of his descendants. During the first part of the 20th century, there were 20 contiguous estates for him and his family in Wellesley. Among other miscellaneous properties, Hunnewell owned the home in which
Horatio Alger's father lived until his death, now called the Horatio Alger House, in
Natick, Massachusetts. Oliver Bacon had built this house about 1824, and sold it in 1869 to Hunnewell. In 1909, Hunnewell deeded the property to the First Unitarian Church of South Natick as a parsonage. ==Legacy==