The use of a tripod is not necessarily a straightforward decision related to holding a camera steady. Yes, it does lead to sharper images for obvious reasons but that is not the end of the story. Using of a tripod also slows down the process of creating an image because it takes time to find a stable location that allows the required view with good light, no shadows cast by photographic equipment etc. This slowing down also incidentally leads to the photographer taking much greater care over the selection of viewpoint and the composition of each shot.
Selection of the correct depth of field is an essential part of setting up each shot. It is a relatively simple matter to measure distances for the plane of focus to the nearest and furthest points in am image which should be rendered sharp. The aperture and shutter speed can then be chosen. A depth of field preview facility, available on most DSLRs, can be used to verify visually that all required image elements are acceptably sharp.
It is not necessarily the case that all parts of an plant image should be sharp. In some cases it is worth experimenting with large apertures, and hence shallow depth of field, to throw areas of an image out of focus. This focuses attention more immediately upon the in-focus elements of a composition.
Backgrounds should be rendered out of focus by controlling depth of field. This reduces potentially confusing or distracting background detail to a soft, blurred wash of colour which the eye tends to ignore. The subject then acquires more impact. If a lens does not have a large enough aperture to throw the background out of focus, try to find a viewpoint that incorporates a more distant background. Alternatively, use a teleconverter or extension ring between the camera body and the lens.