While always a bit of a gamble, there are those who love to live on the garden edge and test the boundaries of what they can plant in their landscapes. For instance if you live in a zone 5, but just have to have that plant that is labeled hardy to a zone 6 and above (the higher the zone the warmer the climate), you might have some luck with strategic placement.
Generally speaking, sunnier places that are protected from wind can be as much as one zone warmer than the rest of your yard. The same is true in the opposite direction… a cold northerly facing spot that gets shade may be a zone cooler than the average zone of your regional climate.
These spots in the landscape are called ‘microclimates’ and typically differ distinctly from the norm, although they often go undetected unless you are consciously looking for them.
Usual places where microclimates might be found are near fences, heat vents, sheds, retaining walls and courtyards. It is not unlikely that an enthusiastic gardener will build a microclimate if one doesn’t already exist. For example, using some decorative fencing perhaps covered with a woody vine can create a warmer microclimate if facing in a southerly direction.
There are no guarantees this will always work and this practice is definitely for the experimental at heart. But there are those that find great excitement in it and enjoy the shear satisfaction out of beating the odds!