When Paul Weissich took charge of the Foster Botanical Garden in 1957, the grounds in Honolulu were a mere 5 or so acres in size.

By the time Weissich retired 32 years later, Foster nearly tripled in size, and the city added four more gardens, spanning some 650 acres home to the largest and most diverse tropical plant collection in the United States.

The veteran landscape architect, Honolulu Botanical Gardens director and author of at least 11 books on plants and landscaping died in Vacaville, Calif., on Wednesday at the age of 92.

“Paul is truly immortal as his gardens will live on forever and touch countless others,” said Joshlyn Sand, current director of botanical gardens.

Born in San Francisco in 1925, Weissich joined the Navy during World War II and served in the Pacific before finishing college at UC Berkeley, majoring in landscape architecture.

In 1950 he planned a two-week trip in Honolulu and told his wife that if he found a job, he would move his family to Hawaii. He found that job working for landscape architect Richard Tongg.

Weissich soon would land a position with the city overseeing the Beautification Division (now called Division of Urban Forestry) planting and maintaining trees across the island. In 1957 he succeeded the legendary Harold Lyon as director of botanical gardens.

During his tenure the number of botanical gardens grew to five: Foster, Lili‘uokalani, Koko Crater, Ho‘omaluhia and Wahiawa. He would later help to establish the Halawa Xeriscape Garden, which is run by the Honolulu Board of Water Supply.

With landscape architect partner Jim Hubbard, Weissich organized the spectacular Flora Pacifica, an annual flower show in the 1960s and 1970s that featured flora from Hawaii and around the Pacific Rim.

For years in his spare time, he maintained a private landscaping practice with Hubbard, designing countless private gardens.

Son Fred Weissich said his father loved his job. “He told me, ‘There was never a day in my life where I had to get up and go to work.’”

Weissich retired in 1989, but his involvement with the city’s gardens continued through the Friends of Honolulu Botanical Gardens.

Horticulture consultant Heidi Bornhorst, who met Weissich in 1976 as a teenage volunteer at Foster, said the man’s impact on Oahu through his tree plantings and gardens is extraordinary.

“He had a total impact on my life,” said Bornhorst, longtime gardening columnist with the Honolulu Star-Advertiser.

Weissich moved back to California in 2013 to be near his family.

He is survived by sons Paul of Vacaville, Bruce of Kent, Wash., and Fred of Escondido, Calif.; 10 grandchildren; and 18 great-grand- children.

Services have yet to be scheduled.