The almond bloom marks the beginning of California’s agricultural year, transforming the landscape with pink and white blossoms as trees emerge from winter dormancy. This short period is the single largest managed pollination event globally. The bloom sets the stage for the state’s production of this globally popular nut, which accounts for approximately 80% of the world’s supply.
The Standard Blooming Calendar
The almond bloom typically spans from late January into the middle of March, making the almond tree one of the earliest fruit trees to flower in California. The peak of the bloom, when most orchards are blanketed in flowers, usually occurs around mid-February. This peak lasts for only two to three weeks before the petals begin to fall.
The bloom is concentrated almost entirely within the state’s vast Central Valley, stretching from Bakersfield in the south to Chico in the north. The overall bloom period is extended because not all almond varieties flower simultaneously. Cultivars like Nonpareil are generally among the first to bloom, while others, such as Mission or Carmel, follow in a staggered sequence to ensure pollen is available for cross-pollination.
How Weather Determines the Exact Start
While the general timeframe is reliable, the exact start date of the bloom is determined primarily by the temperature conditions of the preceding winter. Almond trees require a period of cold temperatures, known as “chill hours,” to successfully break dormancy. A chill hour is counted for every hour the tree spends below 45°F (7.2°C) but above freezing.
Most almond varieties need between 200 and 700 chill hours to ensure a uniform bloom. If the winter is too mild and trees do not accumulate sufficient chilling, the bloom can be scattered, delayed, or weak, negatively impacting the crop yield. Conversely, a prolonged cold period followed by an abrupt warm-up can cause a rapid and compressed bloom. Late-season frost is a concern because the open flowers are susceptible to damage at temperatures around 28°F (-2°C).
The Essential Process of Pollination
Flowering is the necessary precursor to fruit development, which requires effective cross-pollination. Most commercial almond varieties are self-incompatible, meaning they cannot be pollinated by their own pollen. They require pollen from a different variety to produce a nut, making the crop reliant on the western honeybee.
The scale of this requirement results in the largest annual migration of managed livestock globally. Beekeepers transport roughly 1.7 million honeybee colonies—80 to 90 percent of the commercially managed U.S. honeybee population—to the Central Valley orchards each February. Hives are strategically placed, often at a rate of two per acre, to ensure bees efficiently transfer pollen between varieties. This relationship benefits the bees, as almond pollen provides their first substantial natural food source of the year.
From Bloom to Harvest: The Rest of the Year
Once flowers are successfully pollinated and the petals drop, the focus shifts to nut development. The fertilized ovary swells, entering a phase where the hull and shell begin to form. From March through June, the kernel inside the shell develops and hardens, protected by a fuzzy green outer layer called the hull.
By July and early August, the hull begins to dry out and split open, a process known as hull split, signaling that the nuts are reaching maturity. This splitting allows the kernel and shell to dry naturally in the warm California air before harvest. The commercial harvest typically starts in mid-August and continues through October, utilizing mechanical tree shakers to dislodge the mature nuts onto the orchard floor for collection.