Hydroponic lettuce grown indoors, long regarded as niche, is edging into the mainstream as climate change hits outdoor growers and the salad-lovers who depend on them.

• Greenhouses enable "proximity growing" — a hot industry term — where lettuces are shipped shorter distances to markets, saving on freight costs and emissions.

• The rise of indoor growing comes with a new category: "Teen" lettuce, which is larger and crispier than baby greens, yet more tender than a mature head.

Why it matters: While indoor growing is no replacement for vast outdoor fields, it's expected to play a bigger role going forward — evening out the transition between summer and winter lettuce, and filling in when climate-related crop failures strike.

Driving the news: With lettuce production migrating to Quebec, Vegpro International — Canada's largest fresh vegetable producer — has built a 10-acre greenhouse complex for growing hydroponic lettuce year-round.

• It'll specialize in buttery teen leaves of romaine and other varieties, and ship primarily to Eastern Canadian stores and packagers — lending consistency to the lettuce supply and reducing logistics headaches.
• It's currently the "shoulder" season for lettuce, when U.S. production shifts from California to Arizona, and Vegpro's outdoor production moves from British Columbia to Florida.

What they're saying: "There's no doubt that a product grown outdoors will have a more robust texture," Luc Prévost, EVP of sales and marketing at Vegpro, told Axios.

• But with indoor growing, "not only can you do it continuously, but there are very few surprises that can happen."
• Plus, Prévost adds, hydroponics are good for the lettuce supply chain. "When everybody is growing out of the same region ... then people have limited-to-no other options, and that creates panic in the industry. The more diverse the sourcing can be, the better."

Where it stands: Drought and crazy heat left California lettuces wilting and turning brown in the fields this past summer.

• "We can't ship lettuce with defects," Mark Mason, a manager at California-based Nature’s Reward, which grows romaine, iceberg and leaf lettuce, told the Wall Street Journal in September. "There are fields that are near losses."
• Competition for water among Western growers could prompt them to ditch lettuce for more lucrative crops, such as avocados, nuts or citrus.

🥬 Sign of the times: A head of iceberg sold for $11.99 (about $8 USD) in Australia this past summer amid serious weather woes and inflation.

Yes, but: Outdoor growers in California produce about 70% of U.S. lettuce supplies, while Arizona growers furnish the rest. That's not likely to change anytime soon.

• "You're dealing with a pretty resilient industry here," said Richard Smith of the University of California, Davis, a farm adviser on vegetable crop production and weed science.
• While New Jersey, Colorado and Quebec are starting to grow more lettuce, "the Salinas Valley is where people come to see innovation" in irrigation, mechanization and weeding, he said.
• Hydroponic lettuces "are making a little bit of a dent in field-grown lettuce, but so far we're still growing a heck of a lot."

Of note: Food-borne diseases are less of a problem with hydroponic lettuce — in part because birds don't fly around in greenhouses — but they're not unheard of.

Try this at home: Options are proliferating for the hydroponic-curious.

• Lettuce Grow sells an out-of-the-box system called the Farmstand that lets people grow a variety of crops hydroponically, indoors or out.
• "We grow baby plants in the middle of cities, and we send them shorter distances to our customers to grow them on-site," co-founder Jacob Pechenik told Axios.
• He said the average piece of produce travels 1,500 miles, and 40% to 50% goes bad on the way. "If everyone could grow 10% to 20% of their produce at home, it would have a tremendous impact."

What's next: Bigger greenhouses and new lettuce-growing frontiers could bring fresh flavors and textures to North American consumers.

• Teen lettuce is "a little bit bigger and a lot crunchier" than the baby leaves people are familiar with, Prévost said. "They're the type of leaf that could probably hold up to heavier dressings and toppings."
• "By bringing in a whole new texture, you're bringing in a new culinary experience," he said. "We're trying to bring a whole new portfolio of products to consumers."