Garden flowers with diffuse backgrounds

I have been playing around with an idea I first saw in a book of portraits by the National Trust: A Portrait of The National Trust By John Millar.

What I wanted was a diffused, not just blurred, background. It turned out to be more difficult than I first envisaged: The day I chose had the sun coming in and out from behind the clouds which changed not only the brightness and colour balance but the relative brightness of the subject flower to the background. However, I did learn a lot from the exercise. Here are a few of the results – these are test images not final results! The flower is Bee balm (Monarda didyma):

First image with the diffused background
Second image, note that the tonality has changed, especially in the background
This third image is from a slightly different angle. The colour balance is different as well!
This fourth image has a brighter, more distinct background. The angle of view has changed again

Finally a different flower – a daylily:

You may be able to make out that these are pale pink roses behind the daylilies

An interesting exercise. I believe the technique has potential but I need more practice!