Types of compost

I’m new to the forum (hello!) and planning to follow Mel’s formula to fill my new raised garden beds. So far, I have course vermiculite (1/3) and peat moss (1/3), and I’m researching compost types available in my area for the final 1/3 of the mix. So far I’ve found (1) Black Cow (cow manure compost), (2) Earthgro (cow manure and organic compost), (3) chicken manure compost, (4) mushroom compost, and (5) earthworm castings. Are these five sources diversified enough? Should I use them in equal parts? Any other suggestions? I’m planning to start my own compost pile, and will use that in the future to supplement. Thank you in advance for your input!

Hi, Queenvee, and welcome to the forum! Yes, all of those qualify for one of the five types of compost. But, you need to check the label of the bags to verify the contents of the bag. Many bagged composts are largely wood chips and/or peat moss with a little manure or other components added in. If some of the bags have a lot of peat moss, you would want to reduce the amount of bulk peat moss you add to the mix. Bottom line: They may or may not be able to be used in equal quantities depending on the contents of the bag. If the bag is pure compost, such as Black Kow Composted Manure, that bag is a full quantity. But, if the bag is composted wood chips, peat moss, and manure, it would take 2 or 3 of those bags to equal one bag of pure compost. Unfortunately, there is no magic formula, though, and your mixture does not have to be perfect.

Thank you for the tip! Assuming all compost sources are pure (I’ll check), then equal parts of the 5 sources are fine? It’s okay, for example to have as much worm castings as chicken manure? Thanks much!

Hi Queenvee.  Welcome to the Forum from California!  

Regarding the ratios of blended composts, here are some general rules.  1.  All manures sources count as 1 type, that is, manure based, and should be limited to 20-25%.  2.  Earthworm castings are rich and should be limited to 10%.  They are also expensive, so that's a good thing that they are limited.

Of the products you have found, you can use either Black Kow or the chicken compost, though Black Kow is probably a better product for the 20% manure-based compost.  The Earthgro is a soil amendment, not a compost. As Ohiogardener mentioned, read the label to see what all is included so you can make adjustments with the peat moss volume.  Mushroom compost is good and not limited as to the percentage.  The worm castings are good as 10%.  Here is a thread with some bagged products members have used, pictures included.

https://squarefoot.forumotion.com/t21089-recommended-store-bought-compost-photos-of-composts?highlight=compost

I don't know about mixing compost. My experience this season was I bought bulk compost that was advertised as a cow and fish waste mix. Which also seemed to have a lot of small wood chips. Before I found Mel's book I had filled one 4'x4' with a 50% compost/soil then the next 4'x4' had a 33%compost/Vermiculite/Peat Moss. 
Well the results are in and the Soil/Compost plants we more vigorous than the Mel's side. The two plantings are two halves of a single 4'x8' raised bed. 

I believe the compost I used just didn't have enough of the good stuff so the higher percentage side won. 

I used Mel's exclusively in my containers due to the much lower weight and supplemented with slow release fertilizers and a small about of worm compost. These plants all did very well. 

Then the drought hit in early August while we were on travel. It was an ugly sight on return