Final visit to the Three-birds orchid location near Brevard, North Carolina — 2017-08-02

So many of you, dear readers, have asked me about my Three-birds orchids bloom predictions that I thought I’d give you a brief lesson. Please remember that this is not a perfect way of predicting the bloom. Although it has worked for me about 95% of the time, it may not work that well for you. So, here goes:

I did not come up with this scheme. I believe the original “discoverer” was the late Philip (Phil) E. Keenan, author of Wild Orchids Across North America – A Botanical Travelogue (1998, Timber Press). He was a resident of Dover, New Hampshire. I was never fortunate enough to meet Phil, but he is highly regarded and loved by everyone I’ve spoken to about him. I have modified his scheme to work for the Three-birds orchids in my area of the Carolinas. Here is what works for me:

Look for a two-day (or more) consecutive drop in the day’s low temperature (usually early each morning) of 3-5 degrees (F) or more. 48 hours after this, all of the “ripe” flower buds in the entire population will open. I mention “ripe” as a term to refer to plump, upright buds showing either white or some pink color around the edges. If the buds hang down or are still green, then they are not “ripe”.

Here are a couple of examples of “ripe” buds that opened the next day:

Ripe Three-birds orchid buds

Ripe Three-birds orchid buds

For my temperature measurements, I use one of several amateur weather station reports (showing daily values) that can be found in the online web site called, Weather Underground. The particular weather station I use is, which seems to match up well for my purposes. For your own purposes, you should choose a station that more closely represents the actual weather data in the area where the plants are found. On the web page, there is a summary table of data that shows, among other values, the Daily Low Temperature. Each day, I copy the value and plot it on graph paper. This is the graph for 2017, from July 12 through August 5:

Graph of daily low temperatures Graph of daily low temperatures

I realize that this looks a bit messy; my working graph has only the data points on it, but I have gussied up the graph by adding features to show you some of the things to look for in the data. For one, the green rectangles pretty much outline the temperature ranges that we are interested in. You will note the drop in daily lows followed by 48 hours to show the bloom event. You will also note that it is not always exactly a measure of 2 day’s drop in daily low temperature. If the measure of daily low temperatures drops precipitously, let’s say by 15 degrees (F) or more, then it may still be dropping when the flowers bloom. Usually, though, the scheme works as in the green rectangle labeled “Cycle 2”.

My experience shows that the second cycle in the season produces the largest number of open flowers. I have shown the bloom day events with + symbols signifying the intensity of the bloom; +++ being the largest. Keep in mind that on any given day before or after the bloom event, there may be one or two flowers open in the population — those that didn’t get the email… Life is not perfect.

The temperature predictions told me that August 2 would be a bloom day for Triphora trianthophorus or Three-birds orchids in the Pisgah National Forest. It had been 6 full days since there was a bloom cycle in the area. Sometimes, as many as 10 days to two weeks go by before the plants will flower again. The most recent cycle (the 2nd of a possible 4 or 5 cycles) was by far the largest of the season with about 75% of the plants showing open flowers. Today, about 15%-20% of the plants were in bloom. I know all of this appears fairly technical, and it is. It’s important for me to know when to expect the flowers, because the bloom site is about 1 hour 45 minutes from my home. Although there are other subjects to photograph in the Pisgah NF, I had set out with the intent to see the Three-birds orchids one last time for the season.

The drive north was uneventful. A good sign was my seeing a fairly heavy overcast sky. This overcast scatters the light and reduces the chance for strong light with harsh shadows. I parked along the highway near the site and gathered my camera gear. I had walked just a short distance when I saw the first of the flowers. Yes! I always do a mental fist pump (sometimes a physical one if no one is around to see me) when the plants I came to photograph are cooperating.

Wasting no time, I walked into the open woods and set up my camera and tripod in front of a plant with two open flowers:

Three-birds orchids Three-birds orchids

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