When it comes to the weather, we gardeners are prone to hyperbole. Every season, one would think from listening to us, is drastically colder or warmer, wetter or drier than ever before. Has one of us ever said, “Can you believe what normal weather we’re having?” or, “Average enough for ya?” Instead, we seize upon every irregularity in the weather and hold it up as evidence of the capriciousness of nature. In doing so, we fail to notice the underlying order that does pervade the gardening year. We focus on and remember the ice storms and late freezes and early thaws, rather than acknowledge the more numerous “normal” periods throughout the year.
Consequently, we are also reluctant to believe that bloom times–which are most directly influenced by weather–are predictable with any sort of precision by looking at the calendar. Each year is different, we say. We satisfy ourselves with vague terms like “blooms in early spring” or “blooms in late summer, ” because we believe that’s as accurate as we can be. The dates can fluctuate wildly from year to year, you know.
I began recording bloom times in the Cincinnati area in 1996. It began innocently enough as a simple blooming calendar, to help myself in the orchestration of blooming combos in my own garden, but it morphed into an obsession. Nearly every week for 16 years I traveled to local gardens, parks, and arboreta and photographed and took notes on hundreds of varieties of plants (1,200 all together), including trees, shrubs, vines, perennials, grasses, bulbs, and annuals.
As my observations piled up, I began to realize that bloom times were much more regular than I had thought. Yes, early spring can deviate quite a bit from the norm, but even then–more often than not–the winter aconite and the vernal witchhazel began to bloom the week of February 8 (I divided the year into consistent 7-day intervals to avoid vague generalizations like “late April” or “early May”), and at other times of the year, bloom times rarely varied by more than a week from average. And even if the dates were off, the sequence was the same, and I could quickly judge where we were on the calendar and how far we were from normal.
Temperature is the primary trigger in bloom timing, but I suspect that daylength, or photoperiod, plays a bigger role in bloom dates than we acknowledge. Every first-year horticulture student learns that chrysanthemums can be coaxed into flowering by artificially shortening their daylength. I would not be surprised if a lot more plants than we realize are affected in a similar way, even though the influence of photoperiod is usually only discussed in reference to forcing greenhouse crops like mums or poinsettias. Bloom times, in general, are far too regular for it to be otherwise.
Critics Friends like to torment me with outlier observations of an odd plant here or there blooming out of sequence. And early spring has raised doubts in my own mind. Nature seems most chaotic and unpredictable then: freak storms shut down roads, tear down trees, disrupt power. A warm spell can push plants to bloom early, and then a hard frost can turn them to mush. It can be difficult to see the order in nature when our attention is drawn to these extraordinary events, but closer observation of daily events will reveal another picture–one of regularity and predictability. I cannot count how many times I have traveled to check on a plant to see if it was on schedule, not believing that it would be, because “this year is so different,” and was surprised to find it doing its thing, just like it should. Anyone who has seen snowdrops or hellebores or winter aconites pushing up through the crusty snow of late winter has witnessed this same testament to the ordered, cyclical nature of life on Earth. The natural order may appear to be disrupted from time to time, but the drive to get back on track ultimately prevails.