The Early Blooms of Spring

Did you know?

  • Peak bloom dates for the cherry trees in Washington DC have shifted earlier by about 5 days since 1921.

Today, many plants and trees are blooming earlier than they did over the past century due to milder winters and earlier spring thaws. In combination with later fall seasons, the length of the growing season in the contiguous 48 states has increased by nearly two weeks since the beginning of the 20th century.

Earlier bloom times affect entire ecosystems through disrupting plant-pollinator relationships, increasing pest outbreaks, and worsening human allergies. These changes may also impact tourism in some US cities where colorful blooms attract visitors.

The National Cherry Blossom Festival in Washington, DC, which brings more than 1.5 million visitors to the area every year during the peak bloom time of over 3,000 cherry trees, provides a good example of how bloom times impact tourism. The trees were given to the city in 1912 as a gift of friendship from Japan. Their peak bloom date is occurring earlier than it did in the past by approximately five days, largely driven by local temperatures during the winter and early spring. As a changing climate causes spring events such as flower blooms to happen earlier, it could affect tourism and the local economy.

Learn More

  • The graph below shows how the length of the growing season in the contiguous 48 states has increased over the past century compared with the long-term average.

Length of Growing Season
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  • The graph below illustrates how the frost-free season length, defined as the period between the last occurrence of 32°F in the spring and the first occurrence of 32°F in the fall, has increased in each US region from 1991-2012 relative to 1901-1960. Increases in frost-free season length correspond to similar increases in growing season length.

  • This figure shows modeled trends in lilac and honeysuckle first bloom dates at weather stations across the contiguous 48 states. The map compares the average first bloom date during two 10-year periods. Bloom dates are generally happening earlier throughout the North and West but later in much of the South. 

 

Leaf and Bloom Dates
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What you can do:

  • Join the Million Pollinator Gardens Challenge to help improve the health and numbers of pollinators. Lend a hand to pollinators by establishing plants that bloom throughout the growing season. 

Sources:

 

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