I know compost is usually used as a soil amendment, but if you have some left over, think about it: it’s free, it has loads of nutrients, and it’s full of beneficial microorganisms, worms, and other natural decomposers.
If you’ve got trees in your yard, don’t discard the leaves after you rake them up in fall. Chop them up (with a string trimmer) or shred them into little pieces (with a lawn mower) and scatter them over the soil.
A by-product of mushroom farming that’s sold to the public in some places, mushroom compost makes for great mulch. It’s high in calcium and other nutrients, improves water retention, and attracts earthworms.
These materials are relatively cheap, readily available, lightweight, and easy to apply—even my kids love to help me mulch with them.
Also known as bark chips, shredded bark usually comes from the chopped-up outer bark of conifers like fir, pine, and redwood.