Jeff Lowenfels is a garden columnist who became fascinated by soil biology and spent years learning the science well enough to explain it to gardeners. The result is the most important gardening book of the past twenty years — a clear, comprehensive account of the living ecosystem beneath every plant you grow.
The Soil Food Web
The book’s first half is a systematic introduction to the organisms that make up the soil food web: bacteria, fungi, protozoa, nematodes, arthropods, earthworms, and the larger invertebrates. Each organism’s role — what it eats, what eats it, what it releases in its waste — is explained with clarity and precision.
The central revelation is how plants actually feed. The conventional model — roots absorb nutrients dissolved in soil water — is correct but incomplete. Most plant nutrition is mediated biologically: plants exude sugars through their roots to feed specific bacteria and fungi, which cycle nutrients from soil minerals and organic matter and release them in plant-available forms. Kill the soil biology with tillage or synthetic fertilisers and you sever this relationship, making plants dependent on external chemical inputs.
Practical Implications
The second half translates the biology into gardening practice. The key insight: different plants prefer different biological communities, and gardeners can favour either bacteria-dominated or fungi-dominated soil by how they manage organic matter, moisture, and tillage. Vegetables and annuals prefer bacterially dominated soils; trees, shrubs, and perennials prefer fungal-dominated soils. Treating all soil the same is why many plants struggle.
Plants don't eat food. They hire it. The soil food web is the workforce, and the plants are the employers. Your job as a gardener is to create the conditions in which that workforce can thrive.
— Jeff Lowenfels, Teaming with Microbes
6 Key Ideas From This Book
Up to 40% of the carbon fixed by photosynthesis is exuded through plant roots as sugars, amino acids, and other compounds — specifically to feed the microorganisms that cycle nutrients for the plant. This is not waste; it is the plant's nutrition system.
When you apply soluble synthetic fertilisers, plants absorb them directly without needing to maintain their microbial workforce. Over time, the soil biology declines for lack of root exudates, and the plant becomes permanently dependent on external inputs.
Wood chip mulch feeds fungal networks; compost feeds bacterial communities; both protect soil moisture and temperature. The type of mulch matters: wood chips are appropriate for trees and shrubs; compost is appropriate for vegetables and annuals.
The ratio of bacteria to fungi in soil determines what will grow well in it. Annual vegetables and grasses prefer bacterially dominated soils (higher pH, more frequently disturbed); trees and perennials prefer fungal-dominated soils (lower pH, less disturbed).
Exposed soil is a biological dead zone — sun kills microorganisms, rain compacts aggregates, and wind desiccates the surface. Maintaining continuous plant cover or mulch is the single most important thing a gardener can do for soil health.
Unlike most soil biology advocates, Lowenfels is honestly uncertain about the evidence for brewed compost teas as biological inoculants. The chapter on aerated compost tea is a model of intellectual honesty in a field prone to uncritical enthusiasm.
Any Weaknesses?
The science has moved faster than the book. Some of the soil biology research cited has since been refined or complicated, particularly around the specifics of mycorrhizal nutrient exchange and the role of protozoa in nutrient cycling. The 2010 edition (revised from the 2006 original) is somewhat dated in places.
The book is North American in its examples and species references, which affects the specific chapters on organisms and management. The biological principles transfer globally; the specific organisms and management recommendations may not.
Home gardeners who want to understand why some plants thrive and others struggle — and who are willing to change how they manage soil rather than just adding more fertiliser.
Growing a Revolution by David Montgomery for the farm-scale equivalent of this book's garden-scale biology, and Entangled Life by Merlin Sheldrake for the fascinating science of the fungal side of the soil food web.
Landscape architects and urban greening professionals. The book's account of how soil biology determines plant health has direct implications for why street trees and urban plantings so often fail.
The first half of the book is a biology lesson. Some readers will find the taxonomy of soil organisms tedious; others will find it revelatory. Either way, the second half practical section doesn't fully make sense without it.
Frequently Asked Questions
Is Teaming with Microbes worth reading?
Teaming with Microbes changed how a generation of gardeners and farmers think about soil. Its core insight — that soil is a living community to be fed and protected, not an inert medium to be chemically managed — is transformative in practice, well-evidenced in science, and presented with admirable clarity. A must-read for anyone who grows plants.
Who should read Teaming with Microbes?
Home gardeners who want to understand why some plants thrive and others struggle — and who are willing to change how they manage soil rather than just adding more fertiliser.
What is Teaming with Microbes about in one sentence?
Jeff Lowenfels is a garden columnist who became fascinated by soil biology and spent years learning the science well enough to explain it to gardeners.
The Verdict
*Teaming with Microbes* changed how a generation of gardeners and farmers think about soil. Its core insight — that soil is a living community to be fed and protected, not an inert medium to be chemically managed — is transformative in practice, well-evidenced in science, and presented with admirable clarity. A must-read for anyone who grows plants.
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