From the ABC 7 Weather team

Peduncle elongation: Washington D.C. cherry blossom peak bloom forecast

April 4, 2014 - 07:35 AM
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Peduncle Elongation – do you know the definition? It is the indicator of the progress of the peak cherry blossom bloom date!

The peak bloom date is defined as the day in which 70% of the blossoms of the Yoshino Cherry trees are in full bloom. Obviously, this is weather dependent and can vary from year to year; however, the actual Cherry Blossom Festival dates are "set" based upon the average bloom date of April 4th. In fact, taking a look at the statistics, it appears that peak bloom has taken place in a very broad date range, occurring as early as March 15, 1990 and as late as April 18, 1958 (courtesy NPS).

While National Park Service Horticulturists issue several bloom forecasts, they clearly state that "it is nearly impossible to give an accurate forecast much more than 10 days." The forecast for this year's peak bloom is currently forecast for April 8 to April 12. The question on my mind: Will it need to be adjusted?

According to the Park Service, we just began "peduncle elongation" on April the 4th! (see explainer graphics below.)

The way the National Park Service tracks the progress of the trees is by monitoring the progress of the 5 steps of growth. By monitoring these processes the horticulturist can adjust and update the bloom forecast accordingly. Here are the 5 steps and the corresponding imagery. Take a look and then you will be able to better understand the process whether you head down to the basin or not.



1. Green Color in buds 2. Florets visible 3. Extension of florets 4. Peduncle elongation 5. Puffy white - Courtesy: National Park Service

Final thought...if you cannot or do not make it down to see the Yoshino Cherry trees you are not 100% out of luck. Kwanzan cherry blossoms are provide a vibrant bloom and generally emerge two weeks later than the predominant Yoshino trees along the Tidal Basin. To catch a glimpse of these trees one need only to head over to the East Potomac Park south of the George Mason Memorial.

*Special thanks to Adam Caskey for his collaboration with me on this blog.

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