Plant cycles more useful than calendar for some tasks
Plant phenology may be defined as the study of periodic plant life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation).
It is a far more useful technique for estimating when to perform certain gardening tasks than simply relying on your calendar. It allows all of to correlate what and when we should be doing things with the events happening in our natural environment.
Residents in the city of Kingston use the same calendar as people who live at elevations over 2,000 feet in the Catskills, but the gardening seasons are very different. This makes writing a “timely” gardening column that is read by people from both of these areas tricky at times. I realize that most of you who are reading this reside in Ulster County, in the Hudson River Valley, but my summer home is at a much higher elevation in Schoharie County, so just looking out my window and reporting what I see, does not always work!
What also does not work very well is just repeating the information I used last year, or the year before. There is a pretty significant yearly variation in stages of plant development from year to year, regardless of where you live.
This week I am pleased to be able to use some data that was collected by a regular reader. Don is a reader who lives in Freehold, in town of Greenville in Greene County, and he is a wonderful record keeper, as befits his job as a local historian. Don has collected blooming times for all sorts of local plants and he put this data into a spreadsheet that he sent it to me. I have become sadly aware that my memory of specific events from year to year is far less than “perfect”. Freehold is 424 feet above sea level and about 35 miles Northwest of Kingston. It is on the same road as Story’s nursery, which some of you are familiar with.
Don’s data goes back to 2011 for some plants and events, which gives a pretty good range of what can be reasonably expected for most of us. The problem with long-term data is that it is often TOO long term to be of particular, current, use.
There is plenty of variation to consider for even a 6-year average. According to DD (Don’s Data) the earliest date that daffodils were in full bloom at his house in Freehold was March 16, in 2012, and the latest was April 19 in 2014 and again in 2015. That is a pretty wide range of more than 30 days difference! By looking at the data for at least a dozen other plants Don has recorded, it is pretty obvious that 2012 featured a very early spring. Since then, most years blooming seasons have been pretty close to the same dates, except for 2016, which was also a bit earlier than “normal”.
So what is “normal”? Well, if we are calculating “averages” we will not see much variation at all over a very long time period of time. A more useful statistical tool is often the “mode”. The mode is the most frequently appearing number in a sequence of numbers. There can be
more than one “mode” for any given set of data. The “mode” date for daffodils blooming according to DD is April 19 so if someone asks me now, when I expect daffodils to be in full bloom near Freehold this year, or in 2019 or 2020, I would confidently say, “around April 19” and be reasonably confident I will be correct. Of course as we approach that date more closely, the estimate can change with the way the weather has been trending that season.
Part of the usefulness of phenology is correlating seemingly unrelated activities. For example, the ideal time for applying a crabgrass preventing chemical to your lawn, is when the Forsythia is in full bloom. According to DD, that should be around April 25 in Freehold.
Years ago, I was asked by someone from out of state “when would be the best time to visit me in order to enjoy the lilacs in full bloom?” Now, I can make an educated guess that would be between May 5 and 12. One of my concerns as a snowbird, spending my winters in sunny Florida, is that I will not be home in time to fully witness our magnificent spring sequence of bloom. That would be a serious disappointment, but as long as I live at a high elevation, on a north-facing mountainside, I don’t think I have to worry about that!
Bob Beyfuss lives and gardens in Schoharie County. Send him an e-mail to rlb14@cornell.edu.