A few of you have given the black & white component a color tone: sepia, night view, etc. Great idea!
I had a similar thought; use the complementary color of the subject to provide dramatic contrast. The complementary color is easy to determine because the Red, Green and Blue intensities of a color and its complement each add up to 255. For example, the RGB values of the orange of my flower are about (250, 90, 15), so the complementary color has RGB values of (5, 165, 240).
Here is how to use the complementary color to tint your B&W layer:
Using the Color Picker Tool, click on the dominant color of your subject; this will set the foreground color.
Click on the foreground color tile and the color picker dialog will be displayed.
There are 6 radio buttons labeled HSB RGB; note the decimal value in the RGB boxes, but do not close this dialog.
Into each of the RGB boxes enter the value which 255-PreviousValue, then click OK.
Now select the Brush Tool and then the Color Replacement Tool.
Use this brush on the B&W layer to colorize it using this new tint (the Color Replacement Tool paints using foreground color, but preserves the relative intensities).
cats4janTpgettys Thank you both for you kind comments. A lot of the credit belongs to the original photographers of the photos I used. Without their generosity in allowing their photos to be used via sites like Pixabay I would be lost.