Arranging objects, people, animals, and plants for a photograph can be quite difficult, especially if there's noise (e.g., clutter on the floor). It's much easier to photograph an individual person or thing against a solid background and then add/subtract filler items for context. In gardening photography, this is called a specimen shot where the only thing of interest is an individual plant, flower, or leaf, and this kind of photography can be its own separate category in a gardening photography competition.
White backgrounds show a lot of shadows and imperfections, and something white against something white doesn't really show a lot of detail. However, something white against something black can really highlight the details that might have otherwise been missed, and it's dead easy to create a black background, too.
This Instructable shows how to create a black background in a photograph quickly and inexpensively, and while the examples involve plants, this method is not exclusive to gardening photography of specimens. It can be easily used for photographing items, people, and animals. Probably the best part of this method though is that there is very little editing needed.
To create a perfectly white background, please check out my latest Instructable and get tips on making subjects look shiny and wet!
The most inexpensive and potentially the easiest way to create a black background is to photograph outdoors.
You will need a sunny day with long shadows and architectural shade (e.g., a building or a car). If you do not have a dark surface, you will probably want something black to put on the ground such as a sheet of black poster board or black fabric.