Some people are especially attuned to the rhythm of Nature around this region. Darlene Kunde of Yankton noticed something she hadn’t seen before concerning common lilac shrubs at Lewis & Clark Recreation Area. A campground host at the park also remarked in surprise about lilacs near the end of September.
Lilac shrubs (Syringa vulgaris) are commonly grown in northern states. Because they are also predictable in response to season changes, the spring bloom dates of common lilacs have been recorded across the nation since the 1970’s to add to the study of climate variations. First sightings of migrating pelicans, butterflies and appearance of frogs are other phenology markers for spring.
Darlene said that she noticed a few lilac shrubs along Highway 52 in the Lewis & Clark Recreation Area that were in bloom early this fall. Many enjoyed the usual fragrant lilacs in bloom at the park, back in the cool, wet spring.
An explanation for lilacs blooming again in fall is an unusual alignment of day length, temperatures and moisture that mimics spring. According to Dr. John Ball, Forest Health Specialist SD Department of Agriculture and Extension Forester SD Cooperative Extension, the lilacs were fooled, along with some other plants, by the unusual amount of moisture and fluctuating temperatures this fall. More of Dr. Ball’s “Pest Update” is online at http://sdda.sd.gov/conservation-forestry/forest-health/tree-pest-alerts/
When the day length aligned with these conditions this fall, some lilacs responded with another spring bloom. He said that the shrubs that bloomed won’t have flowers next spring, but that the plants would not be permanently harmed. (Repeating Spring is better than repeating Groundhog Day.)