Brown, sticky, and wrinkly, dates seem a sad or unremarkable fruit. But every Ramadan, the Islamic holy month that began on Aug. 1, dates take on tremendous religious significance for the faith’s 1.6 billion followers.

Throughout the world, Muslims will break Ramadan’s required daytime fasts just as Prophet Muhammad did nearly 1,400 years ago: with dates.

But while emulating Muhammad is said to bring blessings, a quirk of seasonal timing and dates’ growing popularity among non-Muslims are making the prized fruit harder to get for Ramadan.

Today’s date aficionados will tell you that Muhammad had a reason for breaking his fast with dates, namely that hunger comes not from an empty stomach, but low blood sugar. Thus, eating two or three dates quickly restores blood sugar, quelling hunger, and prevents overeating after fasting.

Dates appear frequently in the Quran, as well as in Christian and Jewish scripture. In one Quranic passage about Mary, when she is in the pain of child labor, a voice advises her to shake a date palm and replenish herself with the fruits that fall. Dates are also frequently mentioned in hadith, stories and sayings about or attributed to Muhammad.

The Spanish introduced dates to California in the 1700s, but they didn’t take off until the early 1900s, with the introduction of the large, chewy Medjool ― “the Cadillac of dates,” according to Mohammed Abdul Aleem, CEO of Islamicity.com, whose online store sells dates.

Medjools once thrived in Morocco, but were decimated there by disease. In a last-ditch attempt to rescue the Medjools, a Moroccan ruler sent 11 date palm offshoots to California. Those 11 branches became the basis for an American date agriculture that now produces close to 20,000 tons of dates annually, and whose devotees argue about date varieties the way wine connoisseurs argue about vintages and grapes.

Date farmers and ethnic groceries catering to Muslim customers see Ramadan the way toymakers view Christmas: an excellent market opportunity. Many said date sales double during Ramadan.

Oasis Date Gardens, a 175-acre date ranch in Thermal, CA, sells and ships to customers whose orders can be as small as a few 1-pound packages, or as large as pallets with hundreds of pounds of dates, said wholesale manager Greg Somohano. Customers include families, mosques and Muslim prison chaplains.

But this year and for the next couple of decades, everyone on the date product chain ― farmer, wholesaler, retailer, consumer ― faces a dilemma.

Most date varieties are harvested in September and October. Because Islamic holidays are based on a lunar calendar, which is usually 10 or 11 days shorter than the solar-based Gregorian calendar, freshly harvested dates won’t be available for Ramadan for about 20 years. Meanwhile, date buyers and sellers will need to adapt, which means freezing dates, stocking up, and ordering in advance.

That’s easier said than done.

“We do take a hit,” on freezing and storing expenses, said Mark Goulet, general manager at Leja Farms in Coachella, CA. While Leja has been preparing for Ramadan for months now, Goulet said they are still struggling to make all their orders.

While Muslims extol the virtues of dates, their growing popularity as a health food is making them harder to come by.

Some store owners said getting dates on their shelves this year took almost divine interventions. “God only knows how I got these,” said Mohamud Aden, owner of Hamdi Halal in Boston, gesturing vigorously towards a shelf holding two kinds of Saudi Arabian dates in his narrow Islamic grocery and butcher shop.

Aleem said he posted messages on the Islamcity.com homepage and sent emails to website followers as early as December, advising them to order dates early.

For all the business that comes with Ramadan, Somohano said Ramadan is not the only hectic time around his farm. “The other busy time is around Christmas, when Arab Christians are ordering dates,” he said.