Although we tend to think of gardens and sunshine and photography as going well together, in fact, the best time to photograph most gardens and most flower close-ups is on cloudy--even rainy-days. The problem with shooting on bright sunny days is that, as cheerful as they are, that bright sunlight tends to burn out the highlights of light-colored blossoms and it also creates a lot of contrast. Contrast is one of the toughest things to control in terms of exposure, so the more you can avoid it, the easier your life will be. I photographed this peony blossom in one of my side gardens and it was just starting to rain when I made the photo. A few things pushed me into making the photo at this particular moment: one was that I knew that the blossom was at its peak and that a heavy rain would probably destroy the flower (it did). But also, I'd been watching this plant for days hoping for a great shot, but the light was always so bright that I couldn't hold any detail in the petals. The heavily overcast sky of a rainy day was just what I'd been waiting for and it gave the peony a beautiful rich pink color with a minimal amount of contrast--just perfect conditions.
There are some tricks I could have used if I'd really needed to shoot on a sunny day (like putting a diffusion screen between the flower and the direct sun to soften the light), but I really just wanted a "straight" shot made with no extra gear. That decision was part laziness but also, I was using the picture to illustrate a book for beginning photographers--and they weren't likely to own diffusion screens (or the light stands to hold one), so it seemed more honest to shoot the photo in the simplest way possible. Anyway, even though it was raining when I spotted the blossom, I knew that it was a "now or never" shot and so I hauled out the tripod, set up the camera and shot. Good thing I did--the next morning the blossom was completely misshapen by the pounding rain that came during the night and I would never have gotten the shot. The thing I like most about the picture, ironically, is the soft light of the very heavy overcast skies.
So next time you get a cloudy day, head out to the garden and do some close-up work--you'll be pleasantly surprised at how uniformly nice all of your exposures are and just how much color saturation you get in the flowers.