I am lucky enough to have a Wildflower Garden, it is something I have wanted for awhile, not only for it's aesthetic beauty, but also for Photography.
A lot of Australia's native Wildflowers are very tiny and very delicate, some are also big, bold and bright.
I very rarely use a zoom lens for Flower Photography, instead I use my Macro Lens. In bright light, say mid morning or mid to late afternoon you can hand hold your camera for macro shots. I usually do my photography very early in the morning and this requires longer exposures, so I also use a tripod and shutter release.
It has been a real joy capturing the beauty of this planted garden, with the promise of more to come as plantings fill out. It was not an easy task creating this garden and will be the last garden that I will design and create, mainly due to health problems.
For a very soft focus I use an aperture of around the 3 - 4 range, and sometimes 5.6. As sometimes flowers won't wait, and I like to photograph them as soon as they have blossomed and before the bugs and elements get to them. On windy days I use a smaller aperture and higher iso, I don't really like to up the iso from 100, but sometimes you must do it.
When the sun has risen it can be helpful to use a polarising filter to tone down the glare on shiny surfaces.
Photographing Flowers in Gardens can be a strenuous task, requiring much kneeling, odd positions and belly lying, the use of knee pads and plastic covers to lie on as well as sunscreen and a big hat would be advisable for those people who don't like getting dirty or who wish to avoid sunburn.
Macro Flower Photography is a very rewarding form of Photography, it is one I have been doing for a great many years now and I still enjoy it.
But the biggest joy is Photographing the Flowers in the Garden that you have personally grown.