Restoring Nature Action 2: Cultivate Healthy Soil

Nature is in trouble, but we can all play a role in helping to restore essential ecological services in our urban and suburban landscapes, including those of us with modest garden space.

Plants get their water and nutrients from soil, and a healthy natural landscape can provide those needs with little human intervention. Many gardeners, however, face the challenge of degraded soil that offers little to help plants thrive and can contribute to intense stormwater runoff that further erodes soil quality and contributes to poor water quality in the local watershed. Action 2 of our Restoring Nature series focuses on strategies to cultivate healthy soil.

Healthy soil consists of minerals (clay, silt, and sand), organic matter, and about 50 percent porous spaces that hold water and air. Healthy soil is also teeming with beneficial bacteria, fungi, and soil-dwelling animals such as earthworms, which work to break down nutrients so that they can be taken up by plants. In fact, plants share a good percentage of the sugar they produce from photosynthesis with various microorganisms in exchange for access to water and nutrients. Healthy soil holds water longer, making plants more resilient during droughts and reducing runoff during heavy storms.

Our urban and suburban soils are often low in organic matter and compacted, reducing microbial activity and porous space for air and water. Here are several actions you can take to restore and maintain soil health:

• Limit soil disturbance, avoid tilling, and minimize foot traffic and use of equipment, especially when soil is wet. For highly compacted soil, a garden fork can help aerate without turning the soil over.
• Cultivate a dense, layered landscape as recommended in Action 1. Plant roots of various depths will naturally break up compacted soil, and leaf litter will build organic matter in the soil. Covering bare soil with mulch can help protect soil and build up organic matter as plants fill in.
• Limit the use of chemical fertilizers, fungicides, and herbicides which can pollute groundwater and adversely affect soil organisms. Always do a soil test before applying fertilizers and other soil amendments and use the least toxic pesticides if necessary to manage pests. Always follow application instructions.
• Select plants that are best suited to your soil conditions. Native plants have adapted to local soil conditions (whether clay, sand, or silt), as well as pH and moisture levels. In addition, some plants are tolerant of nutrient-poor or compacted soils and urban pollutants.

SMALL SPACE /BALCONY GARDENING TIPS:

For those growing plants in containers, to cultivate healthy soil:

See Container Gardening with Native Plants for more tips and guidance on plant selection.

Use high-quality potting soil rather than garden soil, which can become compacted and not drain properly.

DO NOT add clay pot shards, stones, or fabric to the bottom of the pot as this will prevent proper drainage.

Mulch in fall and spring to provide organic matter to nourish plants.

Repot plants with fresh potting soil every few years, first cleaning any accumulated mineral salts from the container.