Paying Attention to Water, Sunlight, and Winter Cold.
When planning your water-wise gardening, you'll find it very helpful to become well acquainted with the growing conditions in your yard as well as your area. Even the smallest property will have what is termed "micro-climates" created by the house, outbuildings, slopes, low spots, and existing shade trees. By being familiar with your property and its different growing conditions, you can make a more informed, successful choice for the plants you use in the various parts of your landscape
A microclimate is created when a building, large tree or the topography of your property changes the amount of sunlight, water and wind that the spot receives as compared to an open area with nothing but open sky above.
North facing walls: A bed along the north wall of a house or garage is always going to have cooler and shadier conditions with moister soil.
South and West Facing walls: A bed located on the south or west side of the house gets the full brunt of the sun creating hotter and drier growing conditions. In the winter, that bed will also be a little warmer than open areas away from the house, because of the retained heat from the building.
Place moisture loving plants at the base of the slope (where water not absorbed by the soil uphill will collect to create moister growing conditions). i.e. Beebalm (Monarda) and Swamp Milkweed
By identifying these microclimates, you can look for the plants' preferred growing conditions and match them with where they are found on the site.
Winter Cold and USDA Zones
In the larger picture, it is very important to be sure your plant choices are sufficiently cold hardy for your area. Know your USDA zone designation which tells you the lowest expected winter temperature to expect. The smaller the zone number, the colder the winter lows. A USDA zone 4 plant is sufficiently cold hardy to grow in zones 4 (-30° F) and warmer. But a USDA zone 6 plant is not sufficiently cold hardy to grow in USDA zone 4.