If it seems like spring is a little behind schedule for its arrival in northeast Kansas this year, you are correct. According to the USA National Phenology Network (NPN), signs of spring are one to two weeks behind their regular appearances across much of the Midwest and Great Plains.

The NPN uses phenology to monitor when certain things happen each year. Phenology is the study of cyclic and seasonal changes in living things that occur in relation to weather and climate. Bird migrations, plants flowering and fruiting, insects hatching, etc. are all related to these cyclic and seasonal changes. Phenology is especially important to scientists in pest management, crop production, human-health (insects and allergies), ecology, environmental science and climatology.

Throughout history, gardeners have recorded and referenced dates when certain flowers bloom, hummingbirds arrive or certain insects appear. And, even though plants and animals lack the ability to read the calendar, there is a great deal of consistency from year to year in when certain things happen in the natural world in any given place. There are extremes, like the late April freeze that destroyed much of Kansas’ fruit crop several years ago, but overall the daffodils usually bloom around the same time each spring.

For spring, the NPN uses measures they call the First Leaf Index and First Bloom Index. The First Leaf Index is based on leaf out of lilacs and honeysuckles and the First Bloom Index is based on flowering of the same species. Lilacs and honeysuckles are some of the earliest plants to break dormancy in the spring and are widespread across the U.S.

The late arrival of spring this year is in comparison to the First Leaf Index averages from 1981-2010. The date range was chosen by the NPN for a long-term average, and the years since have shown more fluctuations than the years prior.

The Northeast also saw a late arrival of spring based on leaf out this year. Parts of Texas saw a one-week-late arrival of first bloom.

Spring was early in other parts of the country. The NPN reports that spring leaf-out occurred four to five weeks earlier than average in parts of Nevada, eastern Washington, Oregon and California. First bloom arrived as much as 20 days early in much of the Southwest and Southeast.

How much the early and late arrivals of the season mean to the environment is unknown at this point. For gardeners: Plant by what is going on in the world around you rather than the calendar. Perennial flowers, trees and shrubs can handle the cooler than normal temperatures but give summer-loving plants some time. If purchasing plants to install this spring, take special consideration with plants that have been shipped in from southern states that may be several weeks ahead because of the weather discrepancies. The shift may put them into shock.

For more information about phenology and the USA NPN, visit the organization’s website at usanpn.org.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.