Sometimes soil texture is just to difficult to grow anything in.  Using a raised bed may be your best option when soils won't drain well, to gravely or maybe you have rocky soils, or heavy clay soils make it to hard to work with.  Raised vegetable beds are also a great choice for those who don't want to bend over.  

Soil Mix Recipe

• 1 part native soil
• 1 part compost
• 1 part vermiculite (preferred for sandy soil) or perlite (preferred for clay soil).
• 1 peat moss or coconut coir
• Balanced fertilizer (2-4 cups per 100 square feet)

In a pinch, you can go without the native soil when it just isn't available.  However, we have found it to be essential for our growing needs for our area.