Hardiness Zones

Hardiness Zones represent areas of average annual minimum temperatures. The USDA has divided the U.S. in to eleven different zones based on the lowest termperature recorded between 1974 and 1986. Other parts of the world also have Hardiness Zone maps.
  

This information is helpful for determining what plants may survive in your area. Hardiness Zones do not take into account rainfall, summer heat, soil type, or other factors but are still helpful when deciding what plants may grow in your area. Other factors such as lack of snow cover and lack of water can affect a plants survivability.
  

Plants are usually labeled with a hardiness zone and/or a minimum temperature to which they will survive. For example English Lavender Lavandula angustifolia, Hardiness Zone 5 - 8 is sometimes listed - 30 F instead of by zone.  Spanish Lavender Lavandula dentata has a Hardiness Zone of 8 - 9.  This information is more important than whether a plant is marked as a perennial.  Perennial in what zone?
  

My garden is a zone 6 ( -10 F to 0 F) so I can usually grow plants that can survive in zones 6, 5, 4, 3, 2, and 1. If I want to grow a zone 7 plant I may succeed by finding a warmer microclimate in my yard or growing the plant indoors. A microclimate is an area that has a slightly different climate due to wind protection, more shade, more sun, or other factors which create a climate warmer or cooler than the rest of the area.
  

I have been able to grow rosemary by planting it next to the foundation on the south side of my house. The foundation holds and reflects heat back to the rosemary's roots to keep it warmer through the winter.
  

To find your Hardiness Zone

U.S.A.

Other areas of the world
Update March 2012 - the USDA has a new zone map 

Landscape Planning

It is almost the New Year and in spite of whatever the weather may be it is a great time to plan your landscape. 
Planning ahead can help prevent those situations where you bought a plant because you saw it and just have to have it but then don't know where to put it.  Hopefully it will survive  until you find and prepare a spot. 

Make a list of what you think you would like to grow.  Since this blog is about edible landscaping hopefully you have several edible plants on your list.  Trees, shrubs, and perennials can all be edible plants instead of just the typical barberry, potentilla, aspen, or whatever is often grown in your area.  Fruit trees, berry bushes, edible flowers, herbs, and other fruiting and edible foliage plants can be substituted.
Also, make a list of the vegetables, herbs, and other annual plants you would like to grow.  I would recommend beginning with those things you typically eat.  Later you can add what you would like to try.

Next, observe your property and note the sun and/or shade in various parts of your yard.  Consider that when trees are leafed out the sun or shade may be different.  Also, are some areas drier or more damp than others?  Are the some areas that are near downspouts so receive more water? 

Do you know what climate zone you are in?  You can find that information from your local extension service or check the Old Farmer's Almanac site.
The climate zone will help you determine whether the plants you choose will grow outdoors in your area.  If not you may still be able to grow them indoors.