’Tis the seasoning

From June to mid-November, the 100,000-square-foot plant — an assortment of connected buildings near Route 53 — bustles with activity. The company’s approximately 100 employees mix, package, and ship some 1.5 million 1-ounce cardboard boxes of Bell’s Seasoning, a holiday staple of New England kitchens for nearly a century and a half.

“It’s a very seasonal business,’’ said Kevin A. Maguire, president of Brady Enterprises Inc., which has been producing the legendary Bell’s product since 1971. “About 75 percent of the business is between September and December — very similar to Ocean Spray cranberry sauce.’’

A former Ocean Spray executive, Maguire has been head of the family-owned Brady Enterprises since 2003. “I am the first non-Brady to serve as president,’’ he said.

For many New Englanders, the fragrance of Bell’s Seasoning and its colorful, quirky packaging — a big, dark blue turkey surrounded by green leaves — is as much a part of Thanksgiving as pumpkin pie and Plymouth Rock.

“We do very little advertising,’’ Maguire said. “It’s all word of mouth — passed down through generations.’’

William G. Bell, an inventor and cook, started making the seasoning in 1867 in his home in Newton, mixing and packaging imported spices. As the business grew, he moved the operation to industrial buildings in Boston, where he had more space and was closer to the harbor, where merchant ships docked.

Sometime in the late 1800s or early 1900s — corporate history is vague on exactly when — William Bell sold his business to D&L Slade Co., a Boston spice business, which kept Bell on to manage the operation. Slade sold the company to Weymouth-based Brady Enterprises in 1971.

Often in the week before Thanksgiving, Bell’s Seasonings gets an unsolicited endorsement from America’s television hostess and chef, Martha Stewart. On her annual Thanksgiving show, Stewart routinely adds Bell’s to her stuffing or sprinkles it under the turkey’s skin. A box of Bell’s is often visible on the set.

Allison Fishman, who used to work with Stewart and is now a host of Lifetime’s “Cook Yourself Thin,’’ recounted recently in her blog on Saveur.com how Bell’s saved the day when she was late for work because of a car accident and had to hurriedly prepare five turkeys for Stewart’s show.

“It’s good, yes, but on that day, it was more than the scent of sage that calmed me,’’ Fishman wrote. “It was that iconic package, thoughts of Pilgrims, Massachusetts, and Yankee ingenuity. I held that box, channeled that first cold winter for the Colonists, and thought, if they got through that, then I can handle this morning.’’

The all-natural, salt-free product is virtually unchanged since the days of William Bell. Brady Enterprises uses Bell’s original formula and lists the ingredients clearly on the box — rosemary, oregano, sage, ginger, marjoram, thyme, and pepper — although the proportions that make Bell’s special remain a company secret.

The bright yellow, red, and green packaging and the blue turkey also go back to the company’s founding. “I don’t know why the turkey is blue, but I’m not dumb enough to change it,’’ Maguire said.

Bell’s Seasoning began as a New England-only product, but Brady Enterprises has expanded distribution to most of the Northeast. It also is sold in supermarkets in Florida and California and is available from online retailers.

Brady Enterprises will send four-packs of Bell’s Seasoning anywhere in the world as long as the customer pays for shipping. “We get calls from all over,’’ Maguire said. “We’ve sent it to Australia and England and many places in Europe.’’

Brady Enterprises and the Brady family have been prominent in Weymouth for more than half a century. The company was started in 1964 by George Brady with help from his brothers, Jack and William. While George and William have since died, Jack still lives in Weymouth. His son, Jack Brady Jr., is plant manager and his daughter, Mary Gudolawicz, is chief financial officer.

Brady Enterprises began making powdered cocktail mixes, then expanded into other products — artificial sweeteners, powdered lemonade, cocoa mixes, and instant coffee, as well as the Bell’s line, which includes stuffing and other spice blends. Much of the production at the factory in East Weymouth, as well as another plant in South Weymouth, is done under contract for other companies, including Kraft Foods, Sunkist, and Hershey’s.

Although the privately held company does not disclose financial data, the business is growing, according to Maguire.

“Last year was a difficult year for us, as it was for most businesses, but we have been rebounding and have had a good year so far. We will be profitable,’’ Maguire said.

He said operating a manufacturing plant in Massachusetts is not easy. Health insurance, electricity, and water and sewer costs are all high. But unlike many other manufacturers, Brady Enterprises is not considering relocating, according to Maguire.

“The Brady family have been in Massachusetts their whole lives. I don’t see them moving from Weymouth,’’ he said.

Robert Preer can be reached at preer@globe.com.