We have long wondered how the blooms vary by season. There are many possible ways to define this, but one natural and simple way is to use the 1999 Bloom Identification Guide, giving a month-by-month record of when plants bloomed in the SGM.
We have counted the number of plants listed as blooming in a given month in the following way:
- Each "full bloom" for a given plant in a given month counted as one plant blooming that month;
- Each "beginning" or "ending" for a given plant in a given month counted as 0.5 plant blooming that month; and
- The total number of plants blooming each month was the simple addition of those numbers for each month.
There are 137 plants listed in our 1999 Bloom ID Guide, each observed throughout the year. A breakdown of the number by color is given below (see also a histogram). To avoid dealing with colors with small numbers, we have combined the colors as we have on the individual bloom ID pages, given in the second number column below.
Color Number (each color) Number (combined similar colors) white 43 43 cream 6 43 yellow 37 pink 9 24 red 11 orange 4 yellow-green 1 27 green 1 blue 6 purple 19
The number of blooms per month by color shows the surprising result that the number of blooms in 1999 actually peaked in June and July, not in the spring!
The most frequently encountered bloom color does change with time in the following sequence:
Month Dominant Colors January - February Yellow March Yellow and Blue April - May Blue June - July White and Red August - September Red
A plot of the percentage of a given color blooming per month shows that:
- yellow blooms have the most even distribution over the year, showing a broad peak from March - July;
- blue and red blooms have the peakiest distribution;
- blue blooms have a sharp peak from April - June;
- red blooms have a sharp peak from July - August; and
- white blooms have an intermediate distribution, with a broad peak from April - September, with a sharper peak from June - July.
Thus, for example, the dominance of yellow blooms in January and February results from yellow flowers having the most uniform distribution over the year, and not because most of the yellow flowers bloom at that time. You are more likely to see a yellow bloom later, from March to July, but you won't notice the yellow as much due to the other colors present then. In January and February, you won't encounter very many blooms, but those you do encounter are more likely to be yellow than any other color.
These results of course combine observations for all altitudes, and hence observations at a given altitude will probably not follow these composite curves. See 1999 bloom observations by date and altitude.
Also, these results may not correlate well with the maximum bloom as measured by the eye, since some blooms are significantly showier than others. For example, few plants are so stunning as fields of purple lupine (April - July) or blue California Lilac (March - May). However, it certainly measures the number of different species blooming at a given time, and it happens that those particular plants match the peak bloom periods deduced for the color category as a whole.
Now, of course, the question is how representative the year 1999 was. Stay tuned - we'll update this page with later years as they become available!
Copyright © 2000-2001 by Tom Chester and Jane Strong.
Permission is freely granted to reproduce any or all of this page as long as credit is given to us at this source:
Comments and feedback: Tom Chester | Jane Strong
Updated 5 August 2001