SOUTH PORTLAND — When two local businesses partner on a product, the results can be sweet indeed.

It’s especially true when the product is fresh, strawberry ice cream.

Red’s Dairy Freeze in South Portland has been making soft-serve ice cream with strawberries from Maxwell’s Farm in Cape Elizabeth since the late 1980s. The limited-edition treat is only available for a few days a year.

Nancy Frizzle, who manages Red’s, said the ice cream usually sells out within five to seven days.

“It depends on the weather, and this week we’ve been pretty lucky,” she said June 25. “People are buying it by the quart.”

This year the ice cream became available Wednesday, June 22, and was gone by Monday.

“It’s once a year,” Frizzle said. “You want something limited edition, right?”

The Red’s crew goes out to Maxwell’s Farm each year and picks  strawberries for a few hours, Frizzle said. They picked at least 175 quarts this year.

“It’s really hard, but we have so much fun,” she said. “It’s a rite of passage. You have to pick strawberries if you work at Red’s.”

The stems are then plucked off the berries before the fruit is pureed and mixed into vanilla ice cream. Once it’s ready, the crowds line up.

“It’s the thing,” Frizzle said. “It’s what everyone wants.”

While the ice cream is available, seven of every 10 customers order it, Frizzle estimated. The ice cream is served in a cone, a dish, a sundae, or as a shake.

Frizzle said Red’s doesn’t serve artificial strawberry ice cream at any point during the year. The flavor is only available when the berries are fresh.

“It really is the purest it can be,” she said. “People want fresh, not artificial.”

Red’s employees said freshness is one of the big reasons people are so obsessed with the ice cream.

“Farm-to-table is so big now,” Hailey Grohman said. “People like to know where their ingredients come from.”

Customers said they like the local aspect of the ice cream.

“When two local businesses meld their products together, it can’t be beat,” South Portland resident Lacey Goodrich said.

Frizzle said people come from all over to buy the ice cream because “the locals know about it and the tourists have read about it.” She said the treat gets more popular each year, and people are always upset when it runs out.

“It’s grown and grown,” Frizzle said. “We couldn’t pick enough to fulfill what people want.”

She said it’s nice to know how vested people are in the product.

“It’s become people’s summer treat,” Frizzle said. “People are looking for the tradition.”

Red’s strawberry ice cream is usually available on Fourth of July weekend, Frizzle said, but the berries were early this year. It worked out well, though, because this year the ice cream coincided with the Cape Farm Alliance’s annual Strawberry Festival, June 24 and 25 at Maxwell’s Farm.

Customers at Red’s said they were happy the two events overlapped.

“I really like it because we just went strawberry picking at Maxwell’s,” Cynthia Curry, of Portland, said. “It was fun to stop here and get Maxwell’s (ice cream) and have a pint of strawberries in our car.”

“And,” she added, “it’s delicious.”

Kate Gardner can be reached at 781-3661 ext. 125 or kgardner@theforecaster.net. Follow her on Twitter: @katevgardner.

Red’s Dairy Freeze partners with Maxwell’s Farm in Cape Elizabeth each year to make fresh strawberry ice cream.

Lydia Henderson, an employee at Red’s Dairy Freeze in South Portland, pureed strawberries on Saturday, June 25, for the shop’s annual batch of strawberry soft-serve ice cream.

Lydia Henderson prepares a cone of limited-edition strawberry ice cream at Red’s Dairy Freeze on Saturday, June 25.

Red’s Dairy Freeze employee Lydia Henderson, right, with co-worker Hailey Grohman, hands a cone of strawberry ice cream to a young fan of the frozen treat.

Red’s Dairy Freeze, at 167 Cottage Road in South Portland, partners with Maxwell’s Farm in Cape Elizabeth every year to make fresh, strawberry soft-serve ice cream. The limited-edition treat sold out in five days this year.