Her Target boycott was short-lived.

Chastity Garner Valentine, a prolific fashion blogger with 68,000 followers on Instagram, was so fed up when she found out the designer partnership Target announced last August would not — once again — have clothes in plus sizes that she announced a boycott of the company.

A day or two later, she got a call from Target. They were working on a new plus-size line and wanted to see if she would help them promote it.

Fast-forward five months, and Valentine is now one of the brand ambassadors for Ava & Viv, ­Target’s new plus-size brand that will be unveiled in New York on Thursday. It’s the Minneapolis-based retailer’s first new private-label apparel line in seven years and will begin rolling out in mid-February.

“I’m always open to conversations and improvement,” Valentine said in a phone interview from her Bay Area home this week.

A Target spokesman noted the retailer had planned to reach out to her even before she launched her ­personal boycott.

As Target’s design team developed the new line, they decided to hook up with three bloggers — Gabi Gregg, Nicolette Mason and Valentine — who hold a lot of sway in the plus-size fashion community and who have been pushing retailers and brands to offer more stylish options that don’t try to mask their shape.

In December, Target flew the women to Minneapolis to meet with the team behind Ava & Viv, convey their irritations with plus-size offerings, and give suggestions for the fall line. Target also paid them to be models in Ava & Viv’s look book.

“Things don’t ever get ­better if all of the input is ‘We love it,’ ” said Stacia Andersen, Target’s senior vice president of apparel and accessories. “They didn’t hold back.”

Over the years, Target has had a rocky relationship with its plus-size customers. The company’s website once described the color of a plus-size dress as “manatee gray.” And just this month, the firm took some criticism for deciding that plus-size apparel for its upcoming partnership with designer Lilly Pulitzer would be available only online.

“There’s been a lot of frustration from plus-size customers because they’ve felt kind of ignored by Target,” said Mason, a New York-based blogger and Marie Claire columnist. “But I know this is going to change everything for Target.”

Target executives say Ava & Viv is not a response to any criticisms. Rather, they say, they recognized the plus-size market is growing and that Target had the potential to do more with it beyond just offering some of its missy styles in larger sizes.

“This is kind of the flag on the mountain to say we’re going to go after this business,” Andersen said. “We feel this is our time to capitalize on this space.”

Lots of color and prints

The new line includes a lot of color and prints and spans nearly 90 pieces that range from tops and pants to swimwear and dresses. It will constitute Target’s only in-store plus size offering while its plus sizes for its other in-house brands such as Merona and Mossimo will only be available online.

In the past, Target approached the plus-size market by offering a curated assortment of its mainline fashions in larger sizes. But that wasn’t translating into the kind of sales it wanted. So the company decided to offer a more cohesive collection through just one brand.

The Ava & Viv line has been in the works for about a year. But it also aligns with Target CEO Brian Cornell’s goal to revive the U.S. business by elevating its signature cheap-chic categories such as apparel and home.

Marshal Cohen, a retail ­analyst with the NPD Group, said Target is wise to get aggressive on the plus-size market because it’s been underserved. At the same time, it’s been growing at a faster rate than the rest of women’s apparel in the last few years.

“The consumer is looking for a new place to go,” he said, noting that many plus-size offerings are only available online.

J.C. Penney and Macy’s are among those who have been paying more attention to plus-size offerings recently, Cohen added. Some brands have been hesitant to have a plus-size line for fear it could detract from its image. But that’s an oversight, he said, especially with about 35 percent of female consumers wearing a plus size on either the top or bottom.

When Mason saw the Ava & Viv collection in December, she was excited to see items such as a palazzo pant in the mix, which she noted is not something that has been done well in plus sizes.

“Overall, I think it’s a huge step in the right direction: a lot of color, a lot of pattern, a lot of shapes we haven’t seen before from Target and big-box stores in general,” Mason said. “It speaks to a girl who wants to be seen and isn’t afraid of taking a risk in fashion.”

More variety

There are some items in the collection she personally wouldn’t wear, but that’s a good thing, she said, because it means there are more options and variety.

Valentine is especially excited about the Ava & Viv’s fall collection, though she did suggest that Target’s designers add a little more pizzaz to the tops. “The plus-size shopper is looking for the details they can’t find anywhere else,” she said.

Even as the Ava & Viv debut nears, Target has had to explain the decision to offer plus-size clothes from the upcoming Lilly Pulitzer designer partnership online only. A spokesman noted that sales of plus-size clothes in a 2011 designer partnership with Calypso St. Barth sold poorly, contributing to decisions not to include them in later collaborations with designers. Target executives decided to test their appeal again by offering plus sizes from Lilly Pulitzer online.

For Valentine, the blogger and now adviser to Target, the online sales was a move in the right direction and she said she saw no reason to threaten a boycott.

Even so, in the future, Valentine said, she would like to see them “extended inside the store.”