My name is Timothy, and I'm fairly new to gardening. I'm trying to start my first organic garden, but I'm unsure of what soil mix to use. The space I have for a garden is actually a wooden trough. It goes about 18" deep by 18" wide by 6 feet long or so, then bends into a short L for another 3 feet. Anyway, I dug all the old nasty dirt that had all kinds of nasty stuff in it, and I don't know what mix to fill this with. Lastly, to help with drainage, I plan on putting about 6" of gravel on the bottom before I apply any soil mix, etc.
So "what ratio/mix" of "what items" do I need to start my organic garden? I also plan to feed the garden with compost teas and water, of course, but I can't compost here...no room.
First, please skip the 'drainage layer'. It doesn't improve drainage - it simply reduces the amount of soil available for root colonization and raises the location of any perched water the soil might hold. You'll find the science of that, and container soils in general, thoroughly explained here: http://davesgarden.com/community/forums/t/719569/
Also, I can recommend soils, but first it's important to know if we're technically dealing with a container or a raised bed. The physics of water movement is different in containers that have a continuous soil bridge between the soil in the container and the native soil. IOW, if your L-shaped container is resting on the ground, the water will behave differently than if it was being used like a traditional container.
Thanks, Timothy. That is what Al was trying to find out, whether it was a raised bed type container or something isolated from direct contact with the ground. Based on those two situations his advice would be different in each case.
Shoe (who exits stage left so Al can give you the best-in-the-world information!)
The tan material in the pic is Turface. NAPA floor dry is calcined (baked at high temps) diatomaceous earth. It looks and feels a little like perlite, but it has very good internal porosity for very good water retention while still promoting drainage ... and it also has a CEC superior to Turface.