“When I was growing up, I always had to help my family make the mustard,” said Jessica Slater-Hayes, who has been growing the business since she and her husband, Dan, purchased the Denison Mustard Company in 2015. “I never dreamed I’d own the business someday.”

There is one thing, however, that she knew from the start. “Mustard is a love-hate relationship. You either love it, or you hate it.”

For those who love Denison Mustard, this magic in a jar starts in the “mustard house,” a plain, 16-foot by 24-foot repurposed farm shop across the lane from Slater-Hayes’ home in Washington Township. Step inside the shop, and zesty mustard aromas hint at the bold flavors available.

“I make the mustard, and Dan pours the mustard in the jars,” said Slater-Hayes, whose husband works full-time at the ethanol plant in Denison.

-Photo by Darcy Dougherty Maulsby
ABOVE: Jessica Slater-Hayes checks over tubs of mustard being made at the Denison Mustard Company.

The original Denison Mustard is a mix of four simple ingredients: ground mustard seed, vinegar, salt and water. While some people think the product contains horseradish, it doesn’t. The heat comes from the brown mustard seeds. “Our mustard is also a ‘clean’ product with no additives, preservatives or sugar,” Slater-Hayes added.

Achieving the signature flavor of Denison Mustard, which is sold under the brand name Iowa Country Mustard, depends on using the right ratio of ingredients and letting the mixture sit for the right amount of time before the mustard is ready.

How much time?

“We can’t give away all our trade secrets,” Slater-Hayes said. “My mom and I are the only ones who know the recipe.”

Tracing the history

-Photo by Darcy Dougherty Maulsby
The heat in mustard doesn’t come from horseradish, but rather from the brown mustard seeds.

of the “must of mustards”

Mustard is a classic condiment that has been a source of health and pleasure from ancient times to today. Its tiny seeds have long been a symbol of faith, while its pungent flavor is a testimony to good taste. It’s celebrated at the National Mustard Museum in Middleton, Wisconsin, and showcased on National Mustard Day, which is held annually on the first Saturday of August.

Germany has provided the world with a variety of exceptional mustards. The Denison Mustard Company was established in Crawford County in 1885 by Nikolas Moeller, a German immigrant who emigrated to America with his wife and young son in 1869. The Moellers lived in Davenport, Iowa, before settling on a farm near Schleswig in 1881. After moving to Denison in 1885, 45-year-old Moeller started manufacturing mustard from his own special recipe.

He used a large mustard-grinding machine he brought from eastern Iowa. The machine, which included two large, round stones, was powered by one of the two ponies he used for driving around the countryside to sell his popular “Denison Mustard.”

Since Moeller was blind, his children helped him deliver the product, which they ladled out of a wooden barrel to eager customers. Sometimes customers came to Moeller’s home and paid a nickel to fill up a good-sized jelly jar. “He made many friends, for a more gentle, kindly person was hard to find,” noted local history books.

After Moeller passed away in 1928, his son Fred continued to make the mustard until 1939, when the business was sold to Al Ehlers, who later sold it to Deitrich Vannier. Denison Mustard became a multi-generation business again starting in February 1957, when Garth and Hilda Fuller of rural Manilla purchased the company for $3,000. “They were looking to supplement their farm income and have a business that could stay in the family,” said Slater-Hayes, speaking of her grandparents.

They continued using Moeller’s mustard machine (fondly known as the “battle ax”), which had been retrofitted with an electric motor to grind mustard seeds. “I still have that machine,” said Slater-Hayes, who uses heavy-duty electric blenders to make Denison Mustard.

The Fullers supplied local stores and filled special orders for years. Russ Staley has been a good customer for decades. “I was raised on Denison Mustard,” said Staley, who grew up on a farm near Charter Oak and now lives in Cottonwood, Arizona. “I’m going on 92, and I still distinctly remember how good that mustard tasted in my mother’s deviled eggs.”

Staley, who helped his family thresh oats when he was a teenager, remembers how wild mustard plants grew in the oat fields. When the small grains were run through a fanning mill, the mustard seeds separated from the oats. “Then the people from the mustard company would come get the mustard seed,” said Staley, a 1947 graduate of Charter Oak High School.

Staley, who returns to western Iowa each spring and fall, enjoys giving Denison Mustard as a Christmas gift to his friends. “Denison Mustard has its own distinctive flavor,” said Staley, who enjoys the product so much that he’s known as “Mr. Mustard.” “A lot of my friends love it, too.”

New flavors attract new customers

Staley is glad that various generations have carried on the Denison Mustard tradition. After Garth Fuller passed away, Hilda continued to operate the business with her son, Jim, remaining an active part of the business into her 80s. Jim and his wife, Georgann, grew the business when they began running the company in 1995. In addition to selling their mustard locally, the family started promoting their mustard at the farmers markets in Des Moines and Omaha.

The company introduced Iowa Country Honey Mustard in 1997. More flavored mustards followed, including dill, garlic, hickory smoke, Barn Burner (with habanero powder, the mildest of Denison Mustard’s hot flavors), My Thai (with crushed Thai chili peppers, the company’s second hottest flavor), and Volcano (the hottest option, made with ghost pepper powder).

Appealing to a broader population of mustard lovers helped the family keep up with the competition. The July/August 2003 issue of The Iowan magazine featured the company, which was producing 20,000 jars of mustard a year at the time.

Nothing stays the same, however, in any company. “After my step-father, Jim, passed away in April 2015, I offered to help my mom, but she decided to get out of the business,” Slater-Hayes said. “I told her, ‘Let me talk to my banker before you accept any offers.'”

Slater-Hayes knew her banker was a fan of Denison Mustard. Soon the paperwork was complete. “My husband and I bought the business by October 15, 2015,” she noted.

Since then, Slater-Hayes has been helping more mustard lovers enjoy her family’s authentic Iowa creations. There’s nothing quite like the sharp, bright taste of mustard, which adds dimension and depth to classics like burgers, bratwurst, hot dogs and honey-mustard chicken. Slater-Hayes also slathers Denison Mustard on pork chops before grilling. “We spread the mustard on pork ribs, too, before adding a spice rub and smoking the meat,” she said.

This appeals to Nancy Roush from Baxter, Iowa, who has been ordering Denison Mustard since she discovered it at the Heart of Iowa Marketplace in West Des Moines 15 years ago. “This product turned me on to mustard in general. I really like the hotter flavors.”

Roush’s family uses Denison Mustard products on hamburgers, in potato salad and on roasts. It’s also the first layer of flavor on pork butts, ribs, and other meats that the family cooks in their Oklahoma Joe’s smoker. “If you try this mustard, you won’t be sorry,” Roush said. “It’s a great Iowa product.”

Denison Mustard takes culinary creations to a whole new level, without adding too much spiciness. “The ‘heat’ of the mustard cooks out,” Slater-Hayes said. “This mustard is excellent for any recipe that calls for stone-ground mustard.”

Denison Mustard isn’t just for meats, she added. “I mix our honey mustard with olive oil and a squeeze of lemon juice to make a vinaigrette salad dressing.”

The company even makes a special maple mustard, using real maple syrup from Great River Maple in Garnavillo, Iowa, for Popcorn Charlie & Co. in the Quad Cities.

Denison Mustard maintains a loyal following in Iowa and beyond. “My dad is from Schleswig but moved to Oregon more than 50 years ago,” said Kim Worley of Eugene, Oregon, speaking of her father, Larry. “He always liked the original Denison Mustard but hadn’t had it in years.”

When Larry Worley opened his Christmas gifts a few years ago, he was shocked to find Denison Mustard in the box. “‘How did you get this?'” he exclaimed. “He was so happy,” said Worley, who has become a loyal customer.

Serving long-time customers and attracting a new generation of mustard lovers is satisfying, Slater-Hayes said. “We enjoy making gourmet, German-style, stone-ground mustards fresh on our farm. We invite you to try the ‘must of mustards.'”

For more information on Denison Mustard, which offers gift boxes featuring a variety of flavors, log onto https://denisonmustardco.com/.

Denison Dill Deviled Eggs

6 hard-boiled eggs

1 tablespoon salad dressing or mayonnaise

1/2 teaspoon Denison Dill Mustard

1/4 teaspoon salt

Peel eggs, and cut in half. Mix the yolks, mustard, mayonnaise, and salt in a bowl. Add all ingredients to the white halves.