Hi USA-NPN,

This spring, we alerted you three days prior to when your lilacs were predicted to leaf and bloom, an effort we call springcasting. Our hope was that these predictions would help you to more accurately capture the start of leafing and flowering on your lilacs.

Below, we compare your reports of leafing and flowering from Nature's Notebook with our leafing and flowering predictions from the Spring Indices.

We hope that you will join us again next year to report leafing and flowering on your lilacs. Each year that you report adds to a dataset over 60 years in the making and helps us to understand the impact of climate and other factors on plant phenology. Thank you for contributing to this important project!

This year, you reported leafing for 64 cloned lilacs and 216 common lilacs.

How do your reports compare to our predictions of leafing from the Spring Indices?



Our predictions and your reports are not far off! On average, you reported leafing of cloned lilacs 2 days earlier and common lilacs 6 days later than we predicted this event would occur. You reported leafing for 56% of your cloned lilacs and 59% of your common lilacs within one week of our predicted date.

The days difference between reported leaf out in cloned lilacs in 2023. Red sites are earlier than predicted, green sites are later than predicted.

The days difference between reported leaf out in common lilacs in 2023. Red sites are earlier than predicted, green sites are later than predicted.

In general, reports from the Midwest were earlier than expected, while reports from the West were later than expected. The gap between our predictions and your reports of leafing for common lilacs could be explained by multiple causes, such as a delay in getting out to make observations. We'll have to do some more exploration to know for sure!

This year, you reported flowering for 64 cloned lilacs and 221 common lilacs.

How do your reports compare to our predictions of flowering from the Spring Indices?

Again, our predictions and your reports are not far off! On average, you reported blooming of cloned lilacs 2 days earlier and common lilacs 5 days later than we predicted this event would occur. You reported blooming for 70% of your cloned lilacs and 72% of your common lilacs within one week of our predicted date.

The days difference between reported bloom in cloned lilacs in 2023. Red sites are earlier than predicted, green sites are later than predicted.

The days difference between reported bloom in common lilacs in 2023. Red sites are earlier than predicted, green sites are later than predicted.

In general, your reports of cloned and common lilacs showed great agreement with predicted flowering, with a few scattered sites reporting flowering earlier or later than expected.

Your reports of lilac leafing and flowering help to improve the Spring Leaf and Bloom Indices, which are used as an indicator of the start of spring. Knowing when plants will undergo phenological changes has value to agriculture, human health, wildland management, and more. We hope that you will join us again next year to help us continue to ground-truth these predictions of leaf out and flowering in lilacs.

Thank you for continuing this important legacy!