California’s farmers have been plagued by drought in recent years but the problem in 2017 is too much rain. That has squeezed U.S. salad supplies and it may be a several more weeks before supermarket shelves are fully stocked again.

Warmer-than-usual weather meant the winter growing season ended early in southern California and western Arizona. That was followed by heavy rain, pushing back planting in coastal regions of California, which is the largest U.S. fruit and vegetable producer.

The delays have led to shortfalls of crops including lettuce and broccoli and sent wholesale prices soaring. The cost of a carton of 30 celery heads has almost tripled since early February to $25, U.S. Department of Agriculture data show. A carton of 36 hearts of romaine lettuce jumped to about $52 as of April 18, more than four times the cost last year. Prices may remain volatile and “relatively elevated” into mid-May, said Roland Fumasi, a senior produce analyst for Rabobank in Fresno, California.

“The harvestable crop is not at the level that it normally would have been had we not had these planting delays,” he said. “Over the coming few weeks or 30 days, the supply gaps will hopefully be less intense and maybe begin to go away.”

The West Coast is the main U.S. source of crops like leafy greens, cauliflower and broccoli at this time of year. California’s Salinas Valley, dubbed the “Salad Bowl of the World,” grows about 70 percent of the nation’s lettuce, according to the City of Salinas Economic Development Department. Since the start of October, Salinas Municipal Airport received 16.3 inches (41.5 centimeters) of rain, more than four times the 30-year average, according to the National Weather Service.

Atmospheric Rivers

Weather service meteorologist Brian Mejia said California has been inundated with a series of what are called atmospheric rivers — drenching weather systems that have helped to alleviate the dryness that previously gripped the state. The multi-year drought has been nearly erased, except for parts of Southern California.

Abnormally-high winter rainfall disrupted planting schedules for lettuce, celery and spinach in coastal districts, said Timothy Hartz, an extension agronomist at University of California, Davis. Sowing in January and February occurred during short windows between precipitation. Now that winter-planted crops are maturing, there’s restricted availability of some leafy greens.

“Struggles to effectively supply customer demand have likely reached their apex,” Salinas, California-based vegetable producer Tanimura & Antle said on its website this week.

Some of the affected crops have seen heightened demand in recent years, with the rising popularity of vegetables such as kale and cauliflower, said Christine Lensing, specialty crops economist at Greenwood Village, Colorado-based CoBank.

“People just tend to eat more of these things nowadays, because people are more health wise,” she said. “That’s why these supply interruptions are felt so much more through the marketplace.”

More Acres

But the shortfall shouldn’t last too long. Lettuce matures in just a few months, and Salinas Valley growers produce multiple crops a year.

Steve Alameda, 61, the president of Yuma Fresh Vegetable Association and who farms vegetables, melons and alfalfa at Top Flavor Farms in Yuma, Arizona, increased his acreage of lettuce when rains halted planting in January on a second farm in California.

“We saw an opportunity to make some money” he said. “It’s always a risk that if you grow, the market may not want it when it’s time to harvest.”

Not all stores solely rely on West Coast supply. New York-based BrightFarms Inc. produces lettuce, tomatoes and basil in greenhouses to stock supermarkets in cities including Chicago and Milwaukee. Chief Executive Officer Paul Lightfoot said the company has been contacted by additional retailers this year, though its output is already spoken for.

“Surety of supply sounds attractive all of a sudden,” he said.