jewlz, this is just a thought as I don't have true square foot garden soil in my beds. The true believers in the performance of this way of gardening are absolutely dedicated to doing it right up front. Think of it this was when you are looking at cost. Your vermiculite comes out to about $1.75 sq ft based on your space. Look at your other costs that way to see how much difference you are looking at by breaking it down that way. The 1/3 of each part of the mix is something they preach not to deviate from. So, if you want to do it the right way, your investment now will give you peace of mind. Example, your local nursery includes peat in their mix. Too much TOTAL peat and you will have a nightmare on your hands. Read all of the labels carefully. Good luck on whatever you decide.

I was just thinking the extra compost might be better for the veggies? Maybe not! In terms of cost, I think skimping a little on the peat and vermiculite will only save like 8% on cost. So not really too much savings. More than anything, I want to do it right the first time. I'm just having a hard time with what compost to use.

jewlz, the nursery compost will count as one of the five. They each have to be a different source and different compost to be the true Mel's mix. Doing it right the first time means 1/3 of each component. Again, be careful with how much peat is in any of the five you get. Good luck and let us know what you decide.

Which bulk compost sounds better, the mushroom or the premium? Can you sub perlite for vermiculite?

jewlz, I like the mushroom compost mix better. Just find out how much peat they have in it. It is recommended to use the course vermiculite but I think some have substituted. There is a specific SFC forum if you google it. They are heavy duty about the system.

I hope this is not tooooo late, but I build about the same number of beds as you did, and sourced my vermiculite from a pool supply company. it's the same exact stuff at the pool stores, just more expensive at the garden stores. It's used to put under pool linings, so people buy in bulk. You might have to ask them to order for you, but it's less than 1/2 the price.

Thanks! I did call a pool supply company but they were only 4 bucks cheaper per bag and they'd have to order it as they didn't keep it in stock.

Many people use their own version of (modified) Mel's mix... more compost and less of the vermiculite and peat.

Order the vermiculite, pay less, and if you will still have it in time for filling your beds, I would do it. Personally, I would go with the mushroom compost.

It sound good and I am sure you will do fine!

Good luck and report your results.