One of the challenging parts of naturalistic planting is deciding what plants to combine together (header image). Blending species requires an understanding of what grows well in an area along with when plants emerge, burgeon into leaf and fade, start and stop flowering, and yield fruit and seed.
A bloom calendar that captures the minutiae of plants through the seasons is immensely useful for beginners and experts alike.
With January only a few weeks away, now is time to prepare for creating your own bloom calendar for next season that will serve you for years to come.
WHAT IS PHENOLOGY?
Often this tool is called a bloom calendar. But, for design it’s helpful to think bigger picture than just flowers. When do certain plants emerge, have good fall color, or fade into dormancy?
The study of how organisms respond to yearly cyclical phenomena like climate and seasonal shifts is called phenology.
There is power in understanding how plants respond to the progression of the seasons. For example, the citizen science National Phenology Network allows users to track the progress of spring and emergence of pests.
But, these regional or national maps are nothing compared to knowing what is happening in your own backyard. I’m sure you too have chuckled at the references that state this plant blooms from June–October when you know you only get two weeks of color out of it in September. Creating a calendar that captures bloom and other plant growth stages allows for greater accuracy.
Learning the phenology of your site also helps you recognize patterns. It forces you to stop and pay attention to what is actually occurring around you. One of the most beautiful examples of a phenological calendar is the 72 seasons that is observed in Japan, which I learned about from Midori Shintani of Tokachi Millennium Forest. Such trivial events like first peach blossoms, rotten grass becomes butterflies, and wild geese return are celebrated and enjoyed as part of this calendar.
CAPTURING OBSERVATIONS
Do you remember exactly when that plant bloomed this year? Yea, me neither. Capturing observations helps you remember for later.
You should decide how to capture phenology before making your calendar. Consistency helps to be sure that your observations are all in one place.
Writing is a simple approach to note the start, peak, and stop of bloom and other growth stages. Just grab a notebook and use a pencil in case it gets wet outside. I like how James Hitchmough detailed in his notebook not only bloom but emergence. You could also use an actual calendar or day planner to jot down details.
Another approach I use is to take photos on a phone and digital camera. Usually the date is included in the image metadata. You might consider putting them in a specific album so that they are all in one place.
You can also capture gardening tasks in the calendar. Note when you cut the asters back and when they correspondingly flower the following autumn. Jot down when seed are ripe and need to be collected from certain plants.
It’s worthwhile noting when certain plants go dormant as well. That allows you to know when bulbs will be absent and gaps need to be filled.
You don’t have to get everything this year. Capture as much as you can. If you’re like me in the past, you’ll do good up until about March or April, and then it becomes sensory overload trying to capture everything during the grand emergence. Focus on what’s most important. Maybe this year capture perennials and next focus on trees and shrubs. Or, keep it simple and jot down three or five observations each week to slowly build your list.
CREATING THE CALENDAR
A screenshot of my Ephemera Farm Phenology Calendar
While you can add things to your calendar throughout the growing season, I find winter a nice time to go through observations and make one because of the slower pace in the garden. I bet even if you go through pictures from this previous year you would have the beginnings of one!
You can make a calendar on paper, but I prefer to use Excel (or Numbers or Google Sheets).
You can create the calendar based on days or weeks. But, there are some issues with that approach. Some years plants may bloom early or late, so the start date will shift. And, for those of us who work and have busy lives, we might miss the day the first daffodil, lily, or aster blooms.
I prefer the strategy of thinking of a month as three parts: early (1–10), middle (11–20), and late (21–28+). I don’t have to stop and think about what Julian week it is or if it is the first day something has flowered. Swings in bloom are now less of an issue.
This approach also helps me deal with the issue of days moving and unclean breaks in the week. For example, week 1 of 2025 has 3 days in December and 4 in January. It also saves space. Instead of having 365 or 52 columns, I now have 36 uniform columns. I type the species in the first column, and then I will fill in with a color close to the foliage, flower, fruit, or whatever I see that I want to document.
In a spreadsheet, you can highlight cells and fill them with colors. I have a Mac so yours may look different.
One option I like in Excel is the eyedropper in the fill options. The eyedropper is just above Cancel to the left in the box in the center of the image above.
With the eyedropper you can go to a plant photo and choose its color so that you have an accurate color fill in the calendar. The eyedropper zooms in so that you can choose certain color pixels.
I then fill cells to show the early, middle, or late period that a species started flowering and when it stopped. For some plants I will also note emergence, when to cut back, when it goes to seed, or persistence with winter interest.
ASSESS AND REVIEW THE CALENDAR
Once you have a bloom calendar, it helps to pause and look at it. Are there plants you can pair for better color or texture combinations because they have similar timings of bloom or other growth stages? Are there gaps where you miss flowers? For example, I noticed in August this year few things were in bloom.
Your calendar is not static. You can make changes and update it over the seasons. Print it off and walk through the garden with it in hand once a week. Ask yourself what did you miss last year? What is on track? What is early or late?
If you capture phenology over a couple of seasons, you’ll begin to notice patterns of when plants bloom. For example, I can reliably count on Symphyotrichum oblongifolium ‘Raydon’s Favorite’ to bloom right after the autumn equinox. These reliable plants become bellwethers for practices and predictions in the garden.
THE POWER OF THE CALENDAR
Creating a bloom calendar is how I have been successful crafting plant communities at Ephemera Farm. I study when plants emerge, bloom, and perform in the garden. Then I pair them based on my observations. And, this practice has also allowed me to become more intimate with the land around me.
So, get ready to start your calendar with the new year. I’m sure it’ll help you enjoy your garden even more.
WANT MY CALENDAR?
The Ephemera Farm Phenology Calendar features over 130 plants that I grow in east Texas (zone 8b) broken down by early, middle, and late flowering time of each month. It is a great reference for those who are gardening and designing for the Deep South. Plus, as an Excel file you can edit and update it to your site.
You get it free with purchasing my bootcamp The Naturalistic Planting Primer for $49.
Or, you can buy the calendar by itself as a $10 digital download with the button below.