Ok,
So here is the definitive answer. I posted something about this just yesterday and today went out to get the soil for the raised beds I put in today.
Soil
On mission rd just west of the 5 freeway there is a compost and mulch site (open Tues/Thurs 9-4ish). The "mulch" contains biosolids (composted human waste), and the compost (griffith park) may or may not. No pesticides (it is almost all from tree trimmings) and the sanitation district posts content/contamination reports. Last month, the compost was trucked in from a commercial supplier and was of fantastic (slap yo mamma) quality (all veg matter - Bacterial dominated - better for veggies), as of today 6/30, there was a shipment of griffith park compost (composted bark - fungal dominated - good for trees), but the quality is not as good as past months as it is still course and has not fully matured (i'm there at least once a month). After doing some research most bagged (home ★★★★★/lowes) compost/mulch contain biosolids too (feel free to look too).
For my own raised beds I went today to the compost site and found the commercial stuff gone, so I went to Whittier Fertilizer ( there are also places like LGM in El Monte - wholesale but will sell but will fill a pickup if you can get one - by appointment) and got the planting mix (still wood based, but good luck finding all veg). It costs about $29 a cubic yard (fits in a small pickup) and the bagged version goes for about 7 each. Got my truck filled and a 15lb bag of fertilizer for $50 cash. (P.S. ran into Jimmy Williams there today - he sells at the Hollywood farmers market, has a new book out, and started the Goose Creek tomato Laurel sells.)
Bed 1 - Bagged, purchased from home ★★★★★. - Good results
Bed 2 - Griffith park compost - Ok, mixed results, see below
Bed 3 - Planting mix from commercial supplier - wait and see.
In the past I have used the griffith park compost but the results have been mixed. When mixed with native soil, my plants did ok... but it wasn't until I focused on making my own and doing my best to work on my soil without looking for outside compost that things have taken off. I still pick some up - mostly for side dressing corn n stuff. I have found water makes the biggest difference - both hydration and nutrient availability - get a good watering plan.
OK, so here's my opinion. Free city compost -Side dressing... yes. Top dressing..yes. Potting soil/fill...no. Too heavy. A lot of the bagged (HD/Lowes) stuff is heavy too. and expensive. Amendment...yes, but blend well.
Plants
I have purchased from Laurel before. In fact, that is how I first got started. I was loyal, drove all the way down there to pick up plants/hit the sales. TV (tomatoville) turned me on to
winter sown and I have never looked back. Now I send them money and whatever seeds I can give.The generosity of TV is amazing too. I cannot speak highly enough of both! I still go to sales like tomatomania, but I say save your money and gas. Start from seed when possible, thanks to TV it's not hard, and try places like Sunset Nursery, San Gabriel nursery, green arrow, etc... also do the farmers markets like Hollywood or Santa Monica.
Ok. That's it. Hope that helps anyone.
sBox!