Nature’s Notebook

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When I see daffodils popping out of the ground, it lets me know spring is starting to peek through winter. I take pictures of them when I first see them pushing up through the ground. This way, I can keep track from year to year the daffodil’s emergence.

daffodil flowers

Daffodils are the first sign of spring. This year spring is about 10 days ahead of normal. These daffodil flower buds are just about ready to open.

Basically, it is a photo journal that helps gauge how spring is arriving. The fancy word for correlating plant and insect activity (Mother Nature) with the calendar is called phenology.

Keeping up with these correlations can help farmers and homeowners manage their property and crops better. One of the correlations for turf managers is when the forsythia (yellow bells) is blooming, a preemergent should be applied to prevent crabgrass.

The reasoning behind this recommendation is crabgrass starts to germinate when soil temperatures reach 57 degrees F. Forsythia typically blooms about two weeks before soil temperatures are warm enough for crabgrass to begin to germinate. This gives homeowners time to apply a preemergent herbicide. Preemergent herbicides needs to be watered-in or rained on to be effective against crabgrass, so the two week window gives enough time for a rain shower to activate the herbicide for good crabgrass control.

This system of watching for the forsythia bloom is better than just using a date on the calendar because, if the preemergent herbicide is applied too early, it will break down and crabgrass will become a problem in late spring. If the herbicide is applied too late, the crabgrass will not be controlled. The forsythia bloom helps get the timing of the preemergent application just right.

In the 1950s, the US Department of Agriculture sponsored a phenology observation network designed to characterize seasonal weather patterns. Blooms of common purple lilacs were initially used. Later, they used lilacs that were all taken from the same common bush. This removed some of the genetic variation in the bloom times and gave better resolution to the data.

As this program progressed, dogwood and honeysuckle were added to the plant observation list. Observing these plants and when they bloomed helped scientists to track seasonal changes at regional agricultural experimental range stations. Scientists submitted observations on handwritten note cards. This was transcribed by Joseph Caprio at Montana State University. This original data set has become the backbone of the National Phenology Database and is now managed by the USA National Phenology Network (USA-NPN).

Today, the USA-NPN has digitized the data collection process. It supports many groups and agencies conducting phenology monitoring. USA-NPN data sets are open for everyone to view. They also encourage regular citizens to observe phenology. This data is part of the citizen science program called “Nature’s Notebook”.

If you have an interest in phenology, you can view the data and maps.


The maps show how spring is progressing across the southern US for 2018.

You can also be part of the data collection process.

Participating in phenological data collection is not only a personally satisfying experience but also a useful contribution to future generations. Over time, scientists will be able to use phenological information to conduct more in-depth analyses of the changes occurring across the country and planet.


Spring will be 10 days early this year.

Currently, the observations show spring is coming to Caldwell County about 10 days ahead of the average. To explore more data, visit