If you have heavy clay or mostly sand, it will help. If you already have a loamy soil with good organic matter content, it will be mildly detrimental. The peat moss in most potting soils crusts up when it's dry, repels water and inhibits germination. It's also a magnet for cats to crap in if you have that issue. I would mix it thoroughly with the native soil.

If that's the case if you want to put some high quality stuff in in the first place. Biochar, mushroom compost or horse manure compost are some of the things I add for new soil mix, aside from making my own leaves compost and worm casting. I would avoid MiracleGro unless you like fungus gnats taking over your garden. And avoid the Home Depot inhouse brand "Vigoro", it is junk, I wasted a lot money on that stuff when I started. It now take up space in the lowest depth of my raised beds. Even though I didn't intend to till, I ended up having to because there are trees growing around and their roots invade the beds and stealing the nutrients, so you may want to keep that in mind.

These simple soil tests may be of some help,' 1) Soil test for organic material. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top. 2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains’ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up. 3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart. 4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell, to a point. Too much organic matter can be bad as well. 5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy. A lack of earthworms may simply mean they do not have the food they like to eat. While organic matter is needed things such as Peat Moss do little to encourage earthworms to hand around. Your University of Georgia charges $15.00 per sample for a good soil test. http://aesl.ces.uga.edu/soiltest123/Georgia.htm kimmq is kimmsr

gardengal, I'm looking at the ingredients of the gardenmix you provided: Recycled forest products, rice hulls, composted chicken manure, peat moss, worm castings, bat guano, kelp meal, alfalfa meal, oyster shell & dolomite limes (as pH adjusters) compared to the ingredients in the same company's garden soil: Aged recycled forest products, aged arbor fines, composted chicken manure, oyster & dolomite limes (as pH adjusters), bat guano, worm castings, and kelp meal https://kellogggarden.com/products/kellogg/soils/?s=all-natural-garden-soil It looks to me like the primary difference in the two products is the peat moss present in the garden mix that's missing in the garden soil. The peat moss is what would give this garden mix better drainage? The rice hulls not present in the garden soil would simply be another form of compost, right? If I mixed a bulk bag of peat moss with the "garden soil" would I basically get the "mix?" Would you stick with the "mix" If the small volume were the same but the plastic impermeable borders were instead replaced by something porous such as cinder blocks, wood, large rocks, or even better...no border at all...just a mound of dirt in the shape of a 5 gallon bucket? Am I assuming correctly that by adding a permeable or non existent border, the drainage should now be better and the use a normal "garden soil" with NO peat moss is much less of an issue due to increased drainage As always, thank you for your help. I always learn a ton from you and I appreciate all your posts.