Phenology is the study of plants and animals through seasonal changes. By observing and tracking these events, we gain a deeper understanding of life within our gardens.
You may also enjoy seeing how the Fibonacci sequence appears naturally in plants.
Phenology in the Garden
If you like to spend time in the garden (or outdoors in general) you probably already notice various signs and signals that indicate natural seasonal changes are underway.
What encourages the budding of leaves, the blooming of tulips, or the mating calls of peepers?
Why do they start on one day and not another?
And which circumstances lead up to these natural events?
What is Phenology?
The word phenology has two parts—pheno (appearance) + logos (study)—the study of plants and animals through seasonal changes.
The Timing of Seasonal Changes
We see it in everything from budding, flowering, and fruiting, to breeding, nesting, and migration.
By paying attention and recording your observations (see checklist below) you can not only become a more proficient gardener but assist with national volunteer projects that collect this information to give us a better understanding of nature and climate change.
To get started, this short video shows how climate change causes natural cycles to get out of sync:
Nature: It’s All Connected
One of the coolest things about being a gardener (or avid nature lover) is how, over time, you start to notice the profound relationships between living things and the timing of their events. It’s like the ultimate symphony made up of domino effects.
If you live in a cold climate like I do, we hold it all together until late winter. And then we go bonkers waiting for spring. Parades are held when one lone robin makes an appearance. Never mind he was here all along!
The quest to find signs of spring actually begins back in December with the increase in daylight following winter solstice. It’s still freezing outside but the days start to get longer and we know winter cannot outsmart the sun and the tilt of the earth forever.
Several months later, snow gradually melts, we start tapping the trees for sap to make syrup, tree buds start to open, insects appear, and spring fever (the people’s euphoria) sets in.
With insects come the birds, frogs, and bats that feast upon them.
Tree leaves fill out and baby birds hatch in their nests, nicely hidden from predators.
Fledglings leave the nest when food sources are abundant, giving them their best chance to succeed on their own.
These are just a few examples, of course. And on and on it goes. When inter-dependent events are aligned, we have natural harmony.
Daylength, temperature, and moisture are primary influences.
If you have a chance, look for videos featuring Nina Leopold Bradley who describes phenology brilliantly.
It’s not just the natural events themselves, but the correlation between them that we see: there’s perfection in the timing that we cannot afford to tamper with without risking incredible, irreversible losses.
Phenology is What We All Do
Phenology is not magic or woo-woo, but, quite simply how nature works: adapting to climate and weather; acting on favorable conditions.
It’s about survival and ensuring the next generation.
Through thousands of years of evolution:
- Birds aren’t going to migrate until there’s food sources available at their next resting places.
- Bats aren’t awakening from their winter’s rest until there’s lots of insects to gobble up in the air.
- Peepers don’t peep until their intended mates are also out of hibernation and ready to rumba.
- Apple trees produce flowers and then fruit when the conditions are favorable for pollinators and then ripening.
- Bees are most active when nectar and pollen is abundant.
But again, if conditions shift, particularly temperatures and moisture levels deviating from the norm, some symbiotic relationships are thrown off.
It’s not just unusual warmth that can cause issues but the lack of cold, which some plants and animals rely on to sustain their natural cycles.
For example, unseasonably warm temperatures in early spring may prompt one species of birds to take their migratory journey early. Meanwhile, another species with a longer route knows nothing of the warm spell and maintains their usual travel timeline. Upon arriving at their summer grounds, they find the early birds, if you will, have eaten all the caterpillars, and the (now) late-comers struggle to find food.
There are countless examples like this in plant and animal relationships.
Why Should We Care?
In the book, Phenology by Theresa M. Crimmins, Theresa writes:
“…the changes in the timing of seasonal activity in plants and animals we are experiencing have clear and direct effects on population sizes, food webs, and ecosystem functioning. These changes, however, also have effects that we as humans feel more acutely, directly impacting our health and pocketbooks. As the climate continues to change, these impacts are expected to surface in both expected and surprising ways.”
“Advancing phenology [meaning events occurring sooner than they can match with symbiotic partners] is expected to worsen the risk of frost damage in coming decades. The start of springtime biological activity in the United States is projected to advance by up to three weeks by the end of the century1. One set of predictions indicates that we can expect to experience early warm springs followed by damaging freeze events in nearly one out of every three years by the mid-twenty-first century. The same is predicted for Europe and Asia, with up to a third of Europe and Asia’s forests predicted to be threatened by frost damage in future decades.”
How Gardeners Use Phenology
As gardeners, phenology can help guide our planting schedules along with other practical information like our last frost date and the individual planting recommendations on the seed packet or plant tag.
Seasons are our biggest hint, of course. Watching spring unfold never ceases to stir up the desire the start working in the garden. And, imagining a time with limited garden how-tos, you can see how advice based on observations in nature may have seemed helpful.
There are hundreds of these old-fashioned garden sayings based on natural events like the timing of buds and blooms. Some of them are very specific to particular regions and do not apply to others.
For example, plant peas on St. Patrick’s Day may work in regions much farther south than I am, but here in Ontario, Canada, the only thing I’d have if I planted pea seeds outdoors in mid-March is frozen peas.
The saying plant peas when the daffodils bloom does not take into account the fact that there are numerous types of daffodils with a wide range of flowering times from late winter to late spring, so that doesn’t really help. Plus, an early warm spell can get them flowering in winter and that would not be the time to sow those seeds.
That said, it is true that you may find yourself sowing pea seeds at the right time and the daffodils may also be in bloom. But it’s not an infallible rule to sow by.
One expression I do find reliable is the birds will tell you when it’s time to save seeds.
This happens in the fall. I know it’s time to start collecting seeds when the birds start dining on old flower heads on sunny afternoons. I can tell by their enthusiasm that the seeds are getting nice and toasty and just right for seed saving.
Ideas For Keeping Phenological Records
By noting our observations, we become more aware.
Sign up with a phenology organization or simply start jotting down your own notes. I have a Google calendar name Phenology. This makes it really easy to make notes at any time.
I’ve listed some suggestions below. You can adapt it to suit your growing region. It’s much the same as a garden journal with some notes about seasonal natural events added in.
It’s very interesting to compare notes year after year to see how things change and to better understand what timing works best in your garden.
It is also valuable for researchers to have reports from “citizen scientists” as they could never collect so much data without our help.
Spring to fall: record the dates, any unusual weather, and take photos
- Last frost date
- Final melting of ice and snow
- Trees start budding out (pick a particular tree type to observe)
- Trees leafing out
- Trees leaves fully open
- First trilliums in the woods
- Tulips 2″ out of ground
- Tulips blooming
- Apple and plum tree blossoms fully open
- Lilacs budding and blooming
- Poppies in bloom
- Irises in bloom
- Delphiniums in bloom
- Asters in bloom
- First worms out of soil
- First male cardinal mating calls
- First robins (several) in garden | build a nesting shelf
- First peeper mating calls (this can vary by many weeks: it’s very interesting!)
- First bats swooping for mosquitoes in the evenings
- First baby toads
- First bees
- First hummingbirds, Baltimore orioles, and Rose-breasted grosbeaks at feeders
- First butterflies including arriving monarch migrations and moths
- First tomatoes ripe
- First frost (at end of season)
- Also note any unusual weather / temperatures
- Record the planting dates of all annual veggies and how successful the crops were
Some choose to just monitor one type of plant or tree or animal and make daily observations through the seasons and years. It’s not only interesting but a great way to ensure we take time away from madding crowds each day.
Resources
Phenology Groups & Projects
- Nature’s Notebook | This is a national phenology group in the United States.
There’s also an app for Android and iPhone - SciStarter | Online citizen science hub | Find volunteer opportunities that match topics you’re curious or concerned about.
- ClimateWatch and SeasonWatch | Check for a group in your region.
- inaturalistorg | Explore and share your observations from the natural world.
- ebird.org | Your sightings contribute to hundreds of conservation decisions and peer-reviewed papers, thousands of student projects, and help inform bird research worldwide.
Book
Phenology (The MIT Press Essential Knowledge series)
by Theresa M. Crimmins
On the timing of seasonal activity in plants and animals, the impact of climate change, and what each of us, as everyday phenologists, can do to help.
References
- Andrew J. Allstadt, Stephen J. Vavrus, Patricia J. Heglund, Anna M. Pidgeon, Wayne E. Thogmartin, and Volker C. Radeloff, “Spring Plant Phenology and False Springs in the Conterminous US during the 21st Century,” Environmental Research Letters 10, no. 10 (2015): 104008.
Phenology is a big topic but I hope this has given ideas for your own phenological studies. Have fun with it and perhaps you’ll come up with new garden wisdoms to pass along to your grandchildren.
~Melissa the Empress of Dirt ♛