Question
Hi.  I've recently taken an interest in attempting a perennial garden & have been doing a lot of reading.  I live in Illinois & am in zone 5.  What I don't find while reading is a good description of the meaning of the following preference types:  well drained, average to rich fertility, poor fertility,  humus rich, loamy, light...can you help me truely understand???  Thanks much!

Answer
Hi Patti, Perennials that like excellent drainage, never grow where it is wet and perennials that naturally grow on poor soil, don't normally perform well in loose, loamy soil but most perennials that you find at your nursery are not difficult to grow.
Clay particles are small, they hold water and nutrients well, but clay soil drains slowly which most perennials don't like.   Loose, woodland soil drains better, but doesn't hold nutrients well, so for good perennials use a combination of the two.
Drainage is the most important issue to address.  Most perennial beds are elevated to prevent Mother Nature (or you) from overwatering the plants.  Blend about 1/2 clay and 1/2 coarse organic matter. This will give you a good soil mix that will grow most perennials. (You can use a combination of composted leaves, manure, cotton hulls, finely ground pine bark, peat and a little sand.  You don't need all of the above ingredients.  I've used a 50/50 mix of clay and ground pine bark and grown excellent plants.) There will be some exceptions.  Woodland plants grow in decomposed leaf litter, so you'll want to duplicate that for them.  Marginals need more soil moisture, so the bed should not be elevated for them.  However the exceptions are few, most will do well using the mix above.  
Jim