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?

I'd skip the Peat moss component entirely before using "composted" wood chips - especially from a rot-resistant species. I've made beds with essentially 100% "plain" compost, though I'd put in a heavy portion of leaves (from a property with a lot of oak) for their peat-like bulk when I was buying bulk compost from the local mushroom grower

Second, shop around for vermiculite (expanded shale/mica will also work if you stumble on some of that at a discount) IN the "Vermiculite sources" thread here: http://forums.gardenweb.com/forums/load/sqfoot/msg102308319866.html?33 several people in SoCal have found it for less than $20 per 4 cu. ft. bag, and a place in WA has it for ~$30 a bag, so you are bound to be able to do better than ~$38 a bag.

Hm, I thought conifer bark (and I think redwood is a conifer, isn't it?) was supposed to be good for the soil. Or if not necessarily "good", then at least ok for the soil.

I'm checking out the vermiculite thread now (thanks for the link!), and getting some ideas on other places that may carry it for cheaper. It does seem awfully expensive here compared to how much everybody else seems to be paying.

I found vermiculite for around 20 bucks a bag, but since I live in Utah, Mel's foundation sells pre-mixed bags for 9-10 bucks for 2 or 3 square feet, I can't remember. I bought the pre mixed stuff and it worked great.

Hi - I think the Redwood compost wouldn't be a good substitute - totally different properties. At the suggestion of one of the other threads, I used coir (which I think is coconut fiber) in one of my boxes when I ran out of peat moss and it was fine. Ended up buying it at OSH pretty cheap. (Can't remember the exact cost, but I think $7 for a big bag.)

If you want to drive yourself crazy, there are probably 100+threads across GW that go into much greater depth (too much - and some unpleasant!) about peat, peat substitutes, coir, etc.

I've read through a lot of them re: peat subs, but I thought coir was really hard to get soaked well, and then to break up once soaked. Since I'll be working with around 3cu. yards of stuff, and I'll be mixing it all by hand, anything that's too tough or time consuming is going to be a big, big headache, lol.

Hey you guys.. I have a bed with vermiculite in it, but I found out that vermiculite can contain asbestos, so you might want to think about using pearlite instead.

I just googled "asbestos vermiculite" and a lot of articles came up. You can read them for yourself.