Hi i have bought a book called Plants for places and it's by the RHS. There are sections at the beginning which i don't understand, the section WHAT SOIL IS THAT, SUN AND SHADE, WORKING WITH THE SITE, TOUGH SITES AND FROST POCKETS AND SHADE I don't understand. Then it goes on to PLANTS FOR CLAY SOILS, it doesnt explain what clay soil is. After that it list plants that suit clay soil, it doesnt say much about each plant but it says what light hey like, soil well drained, moist, whether the plant is hardy. What confuses me is that the growing conditions change depending where in the world you are. Should i learn and remember the growing conditions that are in the book despite the differences where i live?