Tom Stevenson, 83, who wrote about gardening in The Washington Post for the last 30 years, died yesterday at the Baltimore City Hospital after a heart attack.

Mr. Stevenson began writing about gardening because, first of all, he loved to make things grow. Secondly, he was a conventional newspaperman in his younger days. It was a matter of putting these two skills together. The result was downright advice on everyting from house plants to orchards. His column, which continued to appear until his death, was one of the most carefully read features in the newspaper.

Most of his advice was meant for private people. But now and then Mr. Stevenson would call attention to matters of public interest. In 1964, he wrote a story in which he deplored the condition of the grounds of the Capitol. There were dead limbs out there, he said, and bald spots in the lawns and poison ivy.

As a way of calling his colleagues to action, former senator A.S. (Mike) Monroney (D-Okla.) had that piece reprinted in the Congressional Record. A year later, Mr. Stevenson told his readers that the situation was much improved.

Among those who called upon him for advice was Lady Bird Johnson.

In the course of his career, Mr. Stevenson wrote three books, "The Garden Handbook of Maryland," "Tom Stevenson's Pruning Guide" and "The Washington Post Lawn Guide."

He won the garden writers awards of the American Horticultural Society and the American Association of Nurserymen. He was a consulting editor of the Encyclopedia Britannica and the American Horticultural Society Magazine.

Thomas Stevenson, who lived in Dundalk, Md., was born at Marion Station, Md. He served in the Army in France in World War I. Later, he became a Washington correspondent for a number of newspapers around the country.

In 1932, he founded "The Broadcast Reporter," which is believed to have been the first national radio magazine in this country. He sold the business in 1937 and became a Washington correspondent for The Chicago Tribune. From the late 1940s until the late 1950s, when he retired, he was a train dispatcher with the Baltimore & Ohio Railroad.

It was during this period that Mr. Stevenson began writing about his hobby: gardening. He started in The Baltimore News-American in 1951 and joined The Post a year later. Many of his columns were answers to questions sent in by readers. His work was carried to newspapers across the country by The Washington Post-Los Angeles Times News Service, which was founded in 1962.

Mr. Stevenson's marriage to the former Mary Louise Johnson ended in divorce.

Survivors include five children, Mary Louise Miller of Towson, Md., Betty Goldstein of Fort Myers, Fla., David Sterling Stevenson of Annapolis, Dorothy Lee Bowerman of Monkton, Md., and Thomas Stevenson Jr. of Solomon's Island, Md.; three sisters, Mary Stevenson, Iris Koons and Betty Feemster, all of Tupelo, Miss.; a brother, Edward Stevenson of Glen Burnie, Md., and 16 grandchildren.