How to Compost

One thing to improve your garden this year: build a compost pile. Regardless of soil type, climate, or garden style, compost enhances soil—stronger, healthier plants result.

Why Compost?

Improves structure, water retention (sandy soils), aeration/drainage (clay), nutrient retention, slow-release nutrients, boosts microorganisms, increases heat absorption, buffers pH.

The Basic Four: Greens, Browns, Moisture, Air

• Greens (nitrogen): Grass clippings, vegetable/fruit trimmings, green weeds.
• Browns (carbon): Fallen leaves, straw, sawdust, shredded newspaper.
• Moisture: "Wrung-out sponge" consistency (40–60%).
• Air: Oxygen for aerobic decomposers.

Hot vs. Cold Composting

Hot: Layered greens/browns with moisture/air—generates heat (140–160°F), kills weed seeds/pathogens, fast, high-quality. Cold: Gradual (leaves take 1+ years). Avoid weed seeds/tenacious weeds in cold piles.

What NOT to Compost

Meat, bones, dairy, grease (pests). Pet/human feces (pathogens). Pernicious weeds (rhizomatous roots may survive). Diseased/bug-infested plants, weeds with mature seeds (keep out of cold piles; center of hot piles only if sure). Conifer needles (slow, acidic). Eucalyptus, walnut, laurel leaves (tannins—few okay).

Building a Pile: Layer Cake Method

Beginners: 50% green / 50% brown by volume. Layers 2–8" thick (grass clippings: max 2" — mats easily).

1. Loosen soil under pile area.
2. Layer browns (2–8") over 3'×3' minimum. Water to "wrung-out sponge."
3. Layer greens (2–8"), pull to corners/edges.
4. Sprinkle soil/finished compost.
5. Repeat, watering brown layers, keeping cubical, 3–4' tall.
6. Cap with brown layer + 2" soil if possible.

Troubleshooting

• Won't heat: Low nitrogen. Turn, add high-N materials.
• Strong ammonia smell: Excess nitrogen. Turn, add carbon (straw, shredded paper).
• Rotten egg smell: Anaerobic (too wet/dense). Turn, aerate, add bulky materials.

Moisture: Wrung-Out Sponge Test

40–60% moisture. Add water to dry brown layers, especially edges. Warm/dry climates: water often missing. Cold/wet climates: excess moisture causes compaction. Re-wet top foot as you build slowly.

Air: Build It In

Aerobic microbes need oxygen. No oxygen = anaerobic = rotten egg smell. Build air in:

1. Loosen soil under pile.
2. Bulky materials (straw, brush) at bottom.
3. Layer wet fines (grass) with bulky materials to prevent compaction.
4. Turn at least once.

Oxygen limits later stages. Pile condenses early—turn to reintroduce oxygen, reheat. If compacted from moisture: turn + add bulky materials.

Particle Size & Pile Size

Smaller particles = more surface area = faster decomposition. Chop woody stalks, shred leaves with mower. Warning: all tiny particles can mat.

Hot composting needs 3'³ minimum (4'³ better, max 5'×5'×any length). Self-insulating, sustains 140–160°F 10–14 days, kills weeds/pathogens. Smaller piles won't sustain heat long enough.

Turning & Maintenance

Turn 3–4 weeks after building (oxygen becomes limiting). Reheats with new microbial surge. Turn at least once.

Locate near garden, hose reach, level ground, stockpile space. Under deciduous trees: summer shade, winter sun. Warm/dry: sprinkle pile edges. Cover with plastic/tarp: retain summer moisture, prevent winter leaching.