Many immigrants to the United States come in search of greener pastures. Dutch-born horticulturist Jos Roozen was determined to create them, one yard at a time.

Mr. Roozen established his nursery and landscape business in suburban Maryland in 1975 and set about addressing that great yearning in the American soul, the need for a lush, weed-free lawn. He also became host of a nationally syndicated radio show, “Garden Sense,” dispensing advice on lawn care and other garden needs to listeners and callers for almost two decades.

Mr. Roozen, 70, died Feb. 8 at his home in Fort Washington, Md., five days after his last broadcast of “Garden Sense.” His death is thought to be related to a heart condition, but the family does not yet know the exact cause, said his brother, Eric B. Roozen.

Mr. Roozen came to the United States from the Netherlands in 1971 to gain what he expected to be temporary experience at an American retail nursery. Seeing the economic vitality of the U.S. trade, he decided to stay even though he came from a family with deep roots in the Dutch flower-bulb industry. Soon after he established Roozen Nursery in Fort Washington, his younger brother, Eric, joined him as a partner.

Jos Roozen decided to launch the show, which was also a vehicle for product sales, after the dominant voice on the radio in Washington — WTOP-AM’s Jack Eden — ended his long-running program. After its debut on WMAL-AM in 1999, “Garden Sense” developed a broad fan base of listeners who tuned in to hear Mr. Roozen’s advice on things such as vegetable varieties for wet soil and the importance of selecting the correct springtime crabgrass preventer if a lawn reseeding was in your future.

The hour-long show aired at 8 a.m. every Saturday. Mr. Roozen’s tone was always firm but never hectoring and delivered with an attribute other garden show gurus lacked, a smooth Dutch accent that was authoritative and reassuring. “That was part of the magic,” said Rick Fowler, who joined the program as co-host in 2005.

Listeners would travel from as far as Alabama and New York to visit Mr. Roozen at his nursery, although he never considered himself a media personality, said son Nicholas Roozen. He once took a group of listeners on a spring tour of the bulb fields of Holland, his brother said, where much of the world’s bulbs and cut flowers are raised in broad, flat landscapes of striking spring color. It was a terrain that defined his childhood.

Johannes Geradus Nicolaas Roozen was born March 21, 1947, in Egmond, Holland, into a family of bulb farmers that went back 10 generations. His life in horticulture seemed preordained. He and his brothers grew up in fields of hyacinths and tulips, and as youngsters were put to work weeding and harvesting in an age before the mechanization of bulb production.

“At 10 years old, we were entrepreneurial already,” Eric Roozen said. “We built a little stand by the side of the road selling flowers that we had taken from our father’s field.”

In the United States, Mr. Roozen discovered a populace with lawns of a size unknown in the small towns of the Netherlands — and a dire need to keep them green and thriving. Mr. Roozen advocated prescribed seasonal turf care that relied on types of fertilizers that were more efficient, gentler and less likely to pollute waterways, his brother said.

On the show, Fowler brought the listener’s perspective to their dialogue with the partner he called “Mr. Jos.” (It was pronounced “Yahss”; his last name was pronounced “Rosen.”) When callers posed their questions, he added, Mr. Roozen “didn’t need to bring notes to the studio or go online. He just knew it from experience.”

Mr. Roozen is survived by his wife of 43 years, Brenda Osborne Roozen of Fort Washington; four children, Eric J. Roozen of Washington, Robert Roozen of Fort Washington, Nicholas Roozen of Alexandria and Kimberly Ramos of Haymarket, Va.; two brothers; a sister; and five grandchildren.

In addition to plants, Mr. Roozen developed an interest in ornamental saltwater fish, and for several years sold the fish and the equipment needed to house them. That sideline was later dropped. More recently, he kept exotic birds for himself and built an aviary between his nursery business and adjoining home.

Mostly, he was absorbed by running his nursery and cultivating the radio program. Although the show would be rebroadcast later during the weekend in other markets, Mr. Roozen would work the phone back at the nursery so he could personally answer the questions of listeners in cities as far away as Aberdeen, Wash.

“We were on for an hour” live, Fowler said. “For most talk shows, it would be over. For Jos, it was the beginning of the weekend.”