Southern California’s temperate climate provided ideal conditions for establishing a thriving new citrus industry in the late 1800s. New citrus growers were lured to the region with advertisements of “frost free” farmland, ideal growing conditions, and big profits.
But the early citrus growers quickly learned that on rare occasions, Southern California was subject to extreme frost that could wipe out entire crops and ruin orchards.
Citrus crops and the fruit-bearing trees themselves are susceptible to damage when temperatures drop into — or below — the 20s for a sustained period of time.
With no long-term history of winter temperature ranges, or accurate weather forecasting, the early citrus growers were often caught off guard when severe frost conditions did occur. The growers scrambled to find ways to protect their crops using a variety of methods to create man-made heat.
The practice of “smudging” with smoke from wet or oily fires was used by Native Americans as a cleansing ritual, and it was also widely used by farmers to control insects on crops. The practice was adopted by farmers in California in the mid-1800s to protect various fruit crops from frost damage, but it was not a proven success.
Early attempts to heat orchards included the use of portable open fires hauled through the orchards on wagons, steam boilers, hot water, and other similar tactics. All of these methods proved to be impractical, and were not long-term solutions.
Orchard heaters or “smudge pots” as they were first known, were developed in the late 1800s in California’s citrus orchards to raise the temperature around the trees, and prevent frost damage. Beginning as large pots of burning oil products, the devices evolved into more sophisticated outdoor “heaters” that could be manually metered and regulated.
In the early 1900s, Southern California citrus growers and inventors improved on the open smudge pots by adding covers, adjustable vents, and chimneys.
On May 1, 1909, the Los Angeles Express ran an article declaring 200,000 smudge pots managed by an army of men, women, and children had saved $3,000,000 in crops in Grand Junction, Colorado.
In spite of the orchard heating testimonials, many Southern California citrus growers didn’t believe frost conditions in their region could ever reach such destructive levels, and they chose not to own or maintain smudging equipment.
Mother Nature stepped in with a dose of reality, and provided the first major need for smudge pots and orchard heating with the Great Freeze of 1913.
On Jan. 5, the temperature in parts of Highland and Redlands dropped to a record low of 17 degrees. Citrus growers had little warning of the impending freeze, and the small percentage who had functional smudge pot operations scrambled to get them running.
Lighting smudge pots was no easy task, and “smudger crews” were recruited to manually fill and light each heater. The pots had to be shut down each morning when the temperature rose above the danger zone, and relit again in the evening if the temperature dropped. There was usually enough fuel in a smudge pot — about 3 gallons in early open pots — to run for two nights, and then they had to be refilled.
The frigid temperatures created a frenzy among businesses that supported the orchards. Oil to feed the smudge pots quickly ran low, and fearing huge losses on citrus shipments, the railroads pitched in to bring in extra oil tank cars.
The big chill finally broke on Jan. 8, but the frost had already destroyed a huge portion of Southern California’s citrus crop. California’s overall citrus output dropped by 55% in 1913, and many farms and supporting businesses were ruined by the damage.
Only a fraction of the existing orchards were able to mobilize a smudging effort during the 1913 freeze. But even the small percentage of smudging created a noxious layer of thick black smoke that blanketed Southern California, and prompted some cities to join or intensify efforts to ban the process.
The Great Freeze of 1913 created a turning point for orchard heating, and preparations for future freezes began on a large scale.
In July 1913, the Pomona Fruit Growers Exchange began constructing a 420,000-gallon oil tank to expand their existing oil storage capacity, and improve delivery of oil to orchard heaters during emergencies.
In late September 1913, 20,000 orchard heaters arrived in Los Angeles, and the shipment was just the lead delivery of the 1 million heaters that had been ordered for Southern California.
By 1920, smudge pots had fully evolved into orchard heaters, with chimneys, vents and improved lighting designs. The new designs held 5-10 gallons of fuel, required less frequent refilling, and emitted less smoke than earlier designs.
The Sheu Company of Upland (still in business today) was manufacturing their Smokeless Orchard Heaters by the train carload, and in May 1920, they ran advertisements stating that almost 40,000 units were available for shipment.
When the Great Freeze of 1922 arrived, it seemed many citrus growers had forgotten the lessons of 1913, and were again caught off guard, and without orchard heaters. Some growers had put off the investment, relying on improved forecasting, radio communication, and luck.
The catastrophic 1922 freeze caused a loss of about 50% of the total California citrus crop, which again caused a rapid increase in the purchase of orchard heating equipment. By 1927, storage tanks for orchard heating oil had a capacity of 47,620,681 gallons, and there were more than 2,000 train carloads of oil ready to be dispersed.
Citrus farming in Southern California began diminishing significantly after World War II, when the area began a huge population and housing boom. However, citrus is still an important crop in other areas of the state, and as of 2020 reports, California produces about 40% of the total U.S. citrus crops.
Orchard heating continues to be a necessity, and new methods such as wind machines have been developed. Wind machines have been widely used since the 1930s, and they are more cost effective than orchard heaters. They use large propellers to move vast amounts of warmer air downward, into the orchard.
Today, the design and use of orchard heaters is regulated by various air quality districts, and they are often used in conjunction with other devices such as wind machines. But even with new technology and regulations, the old-fashioned oil-fired orchard heaters are still out in the orchards keeping Jack Frost at bay.