Garden design software

If possible I would like to give fellow enthusiasts the opportunity to play around with garden design software similar to that used by mydeco for houses. However, it would need to be far more sophisticated that a digital collage. In a coastal zone garden, mapping the prevailing winds and adapting to them can be the most important part of coastal gardening so it would need to be able to work out windspeed for example and show how to slow it down with wind breaks. Feasibly, something using Ordance Survey grid references and Google Maps could give an approximate contour to the garden design. Hmm.. still thinking on that !