Initial Planting and Caring for IILEX Crenata "Convexa"

I've built a cedar planter box measuring 61 inches long x 18 inches wide x 26.5 inches deep (or high). I want to plant seven (7) IILEX Crenata "Convexa" (Japanese Holly) in the box but have no idea how to proceed.

The bottom of the box has holes for drainage. I plan to use either 3/4 inch gravel or lava rocks to facilitate drainage. What I need to know is: 1) Do I simply place the gravel or rocks on the bottom. I'm told I should use fabric (landscapers fabric). What role does that play and does that separate the soil from the gravel or lava rocks?, 2) What should I plant the "Convexa" in, i.e. should I fill mostly with top soil and add complete plant food? Should I top it all off with some much?

As you can see I'm clueless. But my friend asked me to do this for her and I'd like to do it right.

Thanks so much.

Skip the gravel in the bottom. Contrary to common opinion, providing a layer of coarse gravel in the bottom of a planter does not facilitate drainage, but can impeded it. It is a situation similar to that of amending planting holes for in-the-ground plants, also a no-no. The changes in soil structure/texture - from of that of the rootball, to the amended hole, to the native soil -actually slows down the percolation of water. In the case of a planter, the gravel acts in a similar fashion. And certainly avoid using landscape fabric, which has no reasonable use other than under a pathway or unmortared patio. Just fill the planters with a good quality potting soil to which you have added some compost for nutrient content. I also recommend adding a slow release fertilizer, something like Osmocote, to any long term container planting. Never use regular garden soil in a planted container - it is too heavy and will also impede proper drainage.

pam - gardengal