Lesson 1
What soil actually is
Soil is not dirt. It is a living system — mineral particles, organic matter, air, water, and billions of organisms per teaspoon. When you plant anything, you are entering a negotiation with that system. Understand it, and you can grow almost anything. Ignore it, and even expensive compost will fail you.
The mineral fraction — sand, silt, clay — determines drainage and structure. Sand drains fast but holds little. Clay holds everything but drains poorly. Silt sits between the two. The ideal loam is roughly 40% sand, 40% silt, 20% clay, but almost no gardener starts with that. You work with what you have, and you improve it with organic matter — the great leveller.
Organic matter is decomposed plant and animal material. It lightens clay, gives body to sand, feeds soil life, and holds moisture and nutrients in a form plants can access. A soil with 5% organic matter by volume is good; 10% is exceptional. Most urban gardens start at 2–3%, which is why compost matters so much.
What you'll learn
- How to identify your soil type in under five minutes
- Why pH matters and what it means for plant choice
- The role of soil organisms and how to support them
- When to dig and when to leave well alone
Numbers that matter
- pH 6.5–7.0 suits most edibles and ornamentals
- pH below 5.5 limits nutrient availability sharply
- Earthworm count: 10+ per spade depth is healthy soil
- Clay particles: <0.002 mm; sand: 0.05–2 mm
- Target organic matter: 5–10% by volume
Squeeze damp soil in your fist — if it crumbles, it's sandy; if it holds a greasy ribbon, it's clay; if it holds shape but breaks cleanly, you have loam.