Professional photographer Leonard G. Phillips has been focusing on flower photography for the past several years. Here are his suggestions for capturing flowers and plants on film.
Consider the light. Shoot on cloudy days, or the hour after dawn or before dusk. Bright, sunny days have too much contrast for film to handle well, resulting in overexposed highlights, washed out color, or black shadows lacking detail.
Use a tripod. Your natural-light pictures will be sharper for it, and in garden photography, the subject isn't going to escape while you set up. Tripods allow the use of slower shutter speeds, so you can use smaller apertures to get greater depth of field with more of the subject in focus.
Shoot on calm, windless days. If the plants and flowers are blowing around, you're forced to use faster shutter speeds. Wind is another reason to shoot at dawn or dusk--these times are typically the least windy.
Pay attention to the background. A good background enhances the subject, while unwanted objects or colors can ruin a picture. After composing your shot, try zooming the focus from foreground to infinity, scanning for unwanted components. Often, adjusting the depth of field to render the unwanted shapes out of focus can solve the problem, as long as the colors work. Remember, if you don't have a good background, you don't have a picture.
Use depth of field creatively. Use shallow depth of field to focus attention where you want it or to "abstract" the background into color patterns. Use deep depth of field to exploit interesting compositional elements at different distances from the camera. Ask, "What purpose will the depth of field serve in this picture?" If you have a depth of field preview button on your camera, you have a most useful tool--take advantage of it.
Check for strays. You may want to remove insects, debris or dirt from the subject. It's easy to miss these when you're concentrating on composition and technical matters.
Bracket your shots. As the saying goes, film is relatively cheap, and great pictures are priceless. You can rarely go back and recapture the same shot, so protect yourself from improper exposure by taking pictures with aperture openings at what you think is the right setting and at one on either side.
Make in-camera dupes. If you've got a great shot in the viewfinder, shoot more than one frame. This way, if the transparency or negative gets scratched, you still have a backup original. In-camera duplicates will always be better than dupes made later in the lab.
Shoot a lot. Study what works and what doesn't. Many people find it extremely useful to log their exposure information for each shot and note the results when the images come back from processing. Look at what other photographers do and learn from them. After learning what you can, ruthlessly edit your work to eliminate all but the best images. It's OK to throw away slides and prints; professionals throw away far more than they keep.
Experiment and have fun. Try lying on the ground for a different perspective, or shooting a flower from directly above looking down, or shooting white flowers by a full moon. And break the rules occasionally, including all of the above suggestions. Many creative, original images come from accidents that happen exploring new territory.