Is it necessary or recommended to put gravel in the bottom of a large container (like a feeding trough) when using it as a vegetable garden? What type of soil and/or compost should I use?
Yamhill County Oregon
There is no need for gravel in the bottom, it just reduces the amount of root space and does nothing for drainage.
In a container the size of a trough, you would be less inclined to change the soil each year. So rather than purchasing bags of potting soil, use a mixture to fill the trough that contains soil, compost, and some potting media. You could layer top soil and mushroom compost for example with a top layer of potting media. Or you could mix them together as you fill the container. Don't forget to fertilize the plants to keep them growing well all season.