Garden Variety: Nurture Your Soil

Adding soil amendments (organic matter and fertilizers that help boost nutrients) increase microbial activity and improve soil structure and water retention. Here's how to do it.

“Feed the soil, not the plants!”

That oft-heard advice for gardeners is solid. Healthy soil depends on a thriving ecosystem of bacteria, fungi, nematodes, insects and earthworms. But how do you create that? By adding soil amendments—organic matter and fertilizers that help boost nutrients, increase microbial activity and improve soil structure and water retention.

You can amend soil anytime, but spring is ideal, as long as the soil is warm enough to be workable and not too soggy. Here are three of our favorites.

COMPOST: When it comes to amending soil—whether sandy, clay or loam—compost is king, whether commercial or homemade. There are several types to choose from, including compost made from kitchen scraps and/or yard waste, composted manure and mushroom compost, a rich, by-product of commercial mushroom farming. Spread a 3- to 4-inch layer in between plants and either turn it into the top few inches, or let earthworms mix it in for you. They love to pull compost bits down into their burrows.

WORM CASTINGS: Yep, we’re talking about worm poo, also known as vermicompost, the rich digested soil worms leave behind. This is the platinum of soil amendments. While it’s often pricey, it helps soils retain water, and it releases nutrients in forms that can be easily absorbed by plants, much like compost. Buy bagged castings online or at garden centers, or harvest your own by starting a red wiggler worm bin.

ORGANIC FERTILIZERS: Bone meal, alfalfa meal, cottonseed meal, fish emulsion and seaweed are all derived from natural sources and are good options. Unlike synthetics, which deliver a quick boost of energy, they release nutrients slowly. Follow package directions to avoid over-fertilizing.