Hi Dana, and welcome to ATP! I hope you like it here.
I haven't tried Mel's Mix because I'm cheap, cheap, cheap.
My way of making ANY commercial mix cheaper is to mix it with screened pine bark. I found a cheap source of CLEAN bark at Lowes, where they called it "bark nuggets" - I think it was just $4 for 2 cubic feet.
(Many bags of "bark mulch" are dirty, wet and have too much powder and fine fibers. I no longer buy any "mulch" (a.k.a. log-yard trash) from Home Depot, only Lowes.)
I screen it and use the biggest pieces as intended, as mulch. If you don't need coarse mulch, you can run a lawn mower over the big chunks and turn them into small shreds.
The finest stuff (powder, dust and fibers) is too water-retentive for me, so I "throw that away" by mixing it with heavy clay soil in raised beds. There, it helps more than it hurts.
I'm much too cheap to fill a raised bed with "store-bought" soilless mixes. I amend my clay with bark, compost and coarse sand or grit. Probably compost is the most important ingredient, but the clay needs a LOT of help, and that much compost is expensive.
My belief is that almost any native soil can be amended and made into excellent soil, as long as you can add a few inches of compost every year, or twice each year. Where I am, drainage and aeration have to be improved a LOT.
The intermediate stuff (1/16" to 3/16" or 1.5 mm to 4 mm) can be mixed with commercial mixes to make them go farther, cheaper.
If the mix you bought was too heavy and held too much water for you, and not enough air, add coarser bark shreds, like 4-5 mm.
If the mix was too "light" and did not hold enough water, add smaller bark fines, like 1-3 mm.
Careful people worry that bark that had no composting at all absorbs a little N from the soil as it decomposes (slower than wood).
I haven't noticed that, but my clay soil benefits so much from being opened up with chunky bark and organic matter that any N deficit is invisible. Also, I use a little chemical fertilizer on my new beds, and beds that did not get enough compost, so the N deficit, if any, is masked.
Good luck, and see you around the forums!
