I think the only possible solution that will allow you to have any garden that received sunlight is to cut down your 20 trees on the northside around the pond, and then fence the area off. next chance you get to cut down another bunch of trees, suct them down in the same area.

The soil should be fairly fertile. If you make a good compost pile each year, that should take care of most of the soil's needs. For the next year.