No, peat moss is not required in any way. It is purely optional and, the debate on the political correctness of using it or not aside, many other organic amendments are better for the garden. You will find a number of current discussions on peat moss over on the Soil & Compost forum here. I have linked some of them for you below. Dave Here is a link that might be useful: Discussion: Peat moss good for the soil?

Sphagnum peat, aka peat moss, is a common ingredient in many potting soils. Potting soils are really soil-less mixes of ingredients designed to accomodate the very specific needs of container grown plants. Peat moss tends to be very moisture retentive, generally of a very small particle size and quite acidic. For these reasons, it should be used sparingly in any potting/container mix. The primary concern of any potting mix is fast drainage and good aeration and too much peat in the mix compromises both of these issues. It is definitely NOT an ingredient I would include in a potting medium to be used for cacti or succulents. For the record, peat is the decomposed remains of various plant products - sedges, mosses (like sphagnum), reeds or assorted other bog loving plants. Sphagnum is a moss that is often used as a decorative item to top off planted containers or to line hanging baskets, etc. Sphagnum peat - or peat moss, as it is most commonly referred to - is the decomposed product, found widely in peat bogs in the upper northern hemisphere. Canada has the world's largest supply of sphagnum peat bogs.

depends on the depth. 14'x5'=70 square feet. To know how much mix you will need we need to figure out the cubic feet. One way to do this is: Length x width x height (in inches) / 1728 = cubic feet. (14')168" x (5')60" x 6" (height) / 1728 = 35 cubic feet of area to fill. If you need 8" of depth then it's: 168 x 60 x 8 / 1728 = 46.6 cubic feet. If you will be purchasing ingredients by the bag you will find the peat and vermiculite in bags with the number of cubic feet on them. The compost is often sold by weight rather than volume so you will have to guesstimate with that. If you intend to purchase some garden soil from a nursery rather than make Mel's mix those places sell by the cubic yard. A cubic yard is 27 cubic feet. Regardless of what you buy, plan on purchasing 10% more than you need. There will be some settling that occurs so any extra will be used soon enough. Hope this helps

Ok, rather than starting a new post, I have another question to ask. As it turns out, vermiculite is crazy expensive. I thought the landscaping supply company would have it on the cheap, but no dice - $38 per 4cu ft. bag, and I'd need 5 bags of it. So, now I'm rethinking the whole mix. I can get Napa Floor Dry for $8.99/bag delivered, but to make up the 1/3 of the mix, it'd take around 20 bags. I'm thinking of maybe 2/3 compost, 1/6 napa floor dry, and 1/6 redwood amendment, which basically looks like ground up redwood lumber. OR 1/3 of the company's premade "essential soil mix", 1/3 compost, and 1/6 napa, and 1/6 redwood. I'm still not sure if the redwood amendment is supposed to be moisture retentive, or provide aeration, or if it's just to change the ph of soil. Maybe it's some combination of all 3?