The dirt beneath our feet is not always the most glamorous part of gardening, yet soil is the foundation for all terrestrial life on earth. The soil all around us is a dynamic network of minerals, organic materials, and living biota. Growing familiar with your garden’s soil can help you make informed choices to support your plants. Healthier soils are more productive, so giving back to the ground you grow in creates a beneficial cycle. Giving your soil the attention it deserves makes gardening easier, year after year.
Get to know your soil
Your garden is a unique place, affected by a host of factors from land use history to the microclimate around your home. Across the Pacific Northwest, the wealth of rainfall we receive tends to make soils acidic — some plants thrive in acidic (low pH) soil, but others may benefit from amendments such as lime to raise the pH. In urban and suburban areas, soils are often lacking because the top soil is often removed during development. This can leave soil compacted, mineral deficient, and lacking in the microbial activity that helps break down organic matter for a healthy soil cycle (see our tips below for adding organic matter and restoring rich, fertile soils). Awareness of the factors affecting your land will equip you with tools to make informed choices in the garden.
Test Your Soil
Rapid testing kits allow you to easily measure the levels of pH, nitrogen (N), phosphorus (P), and potassium (K) in your soil. Once you know your baseline, you can start to introduce soil amendments to ensure your plants have all the nutrients you need.
Feeding Your Soil
When you’re ready to take the next steps to enrich the soil around your home, we’ve compiled a helpful list of tips for where to start. Fall is a great time to begin building quality soil because the warm, moist soil is easier to work with and full of active microbes which help break down minerals and organic matter; however, there are steps you can take at any time of year to begin your journey of soil stewardship.
Compost
Compost is rich organic matter, full of beneficial microbial activity. It offers fertilizing nutrients and can improve soil structure by increasing aeration. Adding compost is a great way to restore dry, compacted soils to a fertile state.
Mulch
Often thought of as synonymous with compost, mulch can be anything that provides a protective layer to retain moisture and warmth. This can include compost but also barks, leaves, hazelnut shells, and anything else that can be spread over your garden. Different types of mulch have different effects – for example, fir bark can increase acidity for growing blueberries, azaleas, rhododendrons, and other acid-loving plants.
Minerals
A proper balance of minerals makes your plants more resilient to pests, diseases, and stress like heat or cold. Assimilating minerals takes time — warm soil temperatures aid microbes in breaking down organic matter. This makes fall a great time to amend soil while microbial life is still active, as soil is still cold from the winter months during the spring planting season. There are numerous minerals at play in a healthy ecosystem, so consider adding these nutrients to your garden:
- Lime is an alkaline mineral that can increase soil pH to lower acidity, while sulfur amendments can lower pH to raise soil acidity.
- Multi-mineral compounds like Azomite (sourced from volcanic ash deposits) and Langbeinite (mined from ancient seabeds) are great sources of potassium, phosphorus, sulfur, and other trace elements that support plant growth.
- Rock phosphate increases the amount of phosphorus and calcium in the soil, both of which aid the growth of healthy, stress-resilient plant cells.
- Kelp meal increases plant growth and resistance to pests and disease, as well as other stresses like drought, cold, and salinity.
Cover Crops
Cover crops are a great way to build quality soil during the off-season for your annuals and edibles. Cover cropping is the practice of growing a short-lived crop to cut down and till into into the soil to increase the amount of rich organic matter. Keeping roots in the soil year-round helps control erosion and hold onto valuable nutrients that would otherwise leach off when it rains. Common cover crops like legumes (red clover, peas, etc) have evolved symbiotic relationships with soil microbes that actually add nitrogen back into the soil. If you’re curious about adding cover crops to your garden routine, check out our in-depth blog post for more info.
Keep It Natural
Plant Perennials
In nature, perennial plants establish robust root systems that allow healthy soil biomes to develop over time. Planting as many perennials in your landscape as possible helps create an ecosystem in your garden, both above and below the ground. PNW native plants like ceanothus (California lilac and buckbrush) and alder are nitrogen fixers, much like the legumes commonly used as cover crops – planting these will help naturally fertilize the surrounding soil.
Leave the Leaves
There are numerous reasons to keep fallen leaves as you tidy up your garden this fall. They provide essential habitat for insects, including pollinators. They break down into nourishing organic matter that enriches the soil. In nature, these layers of organic waste would build upon each other and decompose into rich top soil. You can keep your lawn tidy and still unlock these benefits by raking leaves into areas of your garden set aside for natural processes like these to work their magic.
More Than Just Dirt
Soil is vital to everything you grow and building soil is an investment in the long-term health of your garden. Through routine practices that enrich and protect this important resource, you can enjoy the numerous benefits of a robust soil biome. If you’re looking for more guidance on how to improve your own soils, our experienced team at Cornell Farm is here to help.
