If you place an object in bright light and use a natural shadow behind the object, you will get a strong contrast and a nearly black background in the image. In the following example, I placed the plant just so that it was barely in the sunlight and right next to a shadow, courtesy of my car.
After some fiddling, taking a few shots, and then editing, this is the resulting image:
|I left a little light in the background because I rather liked it, but I could have cropped it out.|
So if you've ever wondered how people got those deliciously inky backgrounds and beautifully lit blooms, now you know and can try it out! No purchase necessary! Architectural shade is best, and the stronger the contrast between the light and the shadow, the better. You will probably have to fiddle a bit and adjust your position for composition purposes, but it's easy enough to do.
I'm so excited about all the holiday cactus in stores right now. I had to buy this salmon colored one. It's love!