I appreciate your response, but since I didn't get one quite soon enough, I did mix my own using appropriate (according to some research I did here on the forum) amounts of sphagnum peat moss, perlite, and vermiculite. I could find the mix you recommend, but the ingredients included mycorrhizae and "ground limestone", neither of which are specifically mentioned by Earthbox for Earthbox usage. I know what mycorrhizae is/are (wasn't sure if it was Earthbox compatible), and "ground limestone" didn't sound specific enough (to me) to necessarily be an appropriate substitute for dolomite, which is apparently a specific calcium magnesium carbonate found in varying concentrations depending on the "ground limestone" containing it. Just "ground limestone" seemed incomplete, so I just added the Earthbox re-planting kit dolomite as usual when re-planting my boxes. When I re-plant, I do empty the boxes, clean out the old roots at the bottoms, and then re-use the medium per the instructions.
I've had very good luck with Earthboxes, but didn't want to buy another bag or two of the planting medium on-line and then have it sitting around for a year if I could locally find a suitable medium for replacement of the relatively small amount I needed. Next year, I'll consider use of the Pro-Mix you recommend, or just get a bag of medium from Earthbox If I need to add growing medium. Thanks.
