Pressure-treated lumber laid on a bed of gravel gives you a fast, easy foundation that will last for decades. Or lay joists on the wood foundation and fill the wood foundation with gravel and lay cement pavers. A paver floor allows water to drain through, so it's perfect for a gardening shed and you can rinse the floor clean with a hose.
This is a wonderful example of putting in plants that will attract the bees needed - the plants like flowering marjoram (and lavender, which flower longer) will ensure that. Borage, of course, is a major bee attractor! Great addition to the productive garden. http://brookegiannetti.typepad.com/velvet_and_linen/2010/07/kitchen-garden-update2.html