New York Times Co. plans to put its consumer product-review site Wirecutter behind a paywall as the publisher looks to further diversify its subscription business beyond its flagship news product.

Starting Wednesday, readers can purchase a stand-alone Wirecutter subscription for $5 every four weeks, or $40 annually. Those who already pay for the Times’ premium digital subscriptions or home delivery will continue to get unlimited access to Wirecutter, with no change to the subscription’s price.

The Times, in its digital incarnation, is seeking to serve some auxiliary needs that traditional print newspapers once served, including by providing recipes and games and by helping users decide what products to purchase, said David Perpich, head of the Times’ stand-alone products group.

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Wirecutter, which the Times Co. bought in 2016, is a consumer guide that reviews everything from cable modems to cat litter.

The Times and most other major news organizations have put a greater emphasis on generating subscription revenue over the past several years, in part because of the uncertainty of the online advertising market.

At the Times, the core news product powered a subscription boom during the Trump years and the early stages of the pandemic, but that growth has slowed in recent quarters.

“The New York Times Company strategy has been about creating content worth paying for, and increasingly using subscription strategies to monetize those products,” said Mr. Perpich, who is the nephew of Arthur Sulzberger Jr. , former chairman and publisher of the Times.

At launch, readers will get nine free Wirecutter articles a month before being asked to pay for a subscription on the 10th article. Only a small proportion of Wirecutter’s readership currently reads more than 10 articles a month, said Linda Li, Wirecutter’s general manager. A small percentage of users visit the site more than 50 times a month. Ms. Li said the site will experiment with the free-article threshold.

The Times will make some Wirecutter articles free periodically “if they provide strong public service,” said a Times spokeswoman. For instance, Wirecutter’s coverage of air purifiers will be in front of the paywall when the subscription product launches amid the wildfires in the western U.S., the spokeswoman said.

Up until now, Wirecutter has generated revenue primarily through affiliate partnerships with online sellers, including Amazon.com Inc. When a consumer follows a link on the site to purchase a product, Wirecutter receives a commission on the sale. Those affiliate relationships will continue, providing a way to monetize nonsubscribers.

The Times isn’t alone among news organizations in seeking growth from product reviews with affiliate links. USA Today publisher Gannett Co. said earlier this summer that it had doubled its staff over the prior 18 months for a product-review site it sees as a Wirecutter rival.

The Times’ move to generate subscription revenue for Wirecutter is similar to what the publisher has done with its popular cooking and games products. Both are also included in the Times’ all-digital-access subscription, which costs $25 every four weeks. The Times’ basic-digital-access subscription, which excludes those products, costs $17 every four weeks.

David Clinch, a digital-media consultant, said the decision to put Wirecutter behind a paywall made sense for the Times’ strategy.

“If you are ever going to charge for valuable content, you should charge for it when you have a strong and growing audience, not when you’re weak or losing audience,” said Mr. Clinch, who runs consulting firm Clinch Media.

The Times added 140,000 total subscriptions in the second quarter, including 77,000 for news, down from a record-setting 669,000 new digital subscriptions in the second quarter of 2020. Revenue in the quarter grew 24% from a year ago, boosted by strong advertising sales.

Wirecutter’s affiliate revenue is part of the Times’ “other” revenue category—which generated $42.8 million in revenue in the second quarter, up 8.7% from a year ago.

Mr. Perpich’s group oversees the Times’ cooking and games subscriptions, as well as Audm, a subscription-based app for long-form audio journalism. Those products had a combined total of 1.8 million stand-alone subscriptions at the end of the second quarter.

The Times crossed eight million total paid subscriptions across all its platforms just after the quarter ended.

The company doesn’t currently plan to build a subscription product around its growing audio division, which includes the popular podcast “The Daily,” nor to bundle Audm with its all-digital-access subscription, Mr. Perpich said.

The Times has more than 100 million registered users, while Wirecutter attracts about 12 million readers a month, Ms. Li said. As many as one-quarter of Wirecutter readers are also subscribers or registered users of the Times, she said.

Wirecutter was founded in 2011 by Brian Lam, a former editor in chief of tech-news site Gizmodo. The Times acquired Wirecutter five years ago for about $30 million. Its staff and monthly unique visitors have tripled since the acquisition, said a Times spokeswoman. She said that Mr. Lam left his advisory role with Wirecutter and is no longer with the Times.

The new subscription model isn’t expected to bring any personnel changes to Wirecutter, where Ben Frumin will continue to serve as editor in chief.

Write to Patience Haggin at patience.haggin@wsj.com