Question
I am in zone 5 in Michigan.  We built a home in a wooded area.  Unfortunately most of the trees are mature red oaks.  Of which we left several for shade.  I have been trying to grow a shade garden under the oaks, with out success.  I have added bags of ag lime to the soil. It seemed to help somewhat.  But my hostas still are not thriving. Is there anything I can do, besides mulching and letting it go.

Answer
Hello Brenda - your Red Oaks are probably the toughest shady conditions to garden under, other than a rain-forest canopy!  

However, there is a lot of areas in the US that fall into a Zone 5.  Here is an excellent site (from Missouri, which is mostly zone 5a/5b), discussing the challenges you may be facing...

http://www.savvygardener.com/Features/shade_gardening.html

As you can tell by the article above, there are more plant options in zone 5 shade gardening than just hostas.  If the plants in the article are not quite what you need, here is a website with more zone 5 deep shade plants to look at:

http://www.backyardgardener.com/shade/zone5.html

Hope it helps.  ~Marc