Composting: Turn Yard Trash Into Garden Gold

Why it matters

Compost is the cheapest way to build soil that holds water and feeds plants, and both of those decide how much you harvest. Texas A&M AgriLife rates compost as the best mulch for a home garden, and a well-run hot pile also kills most weed seeds before they reach your beds.

Step by step

1. Pick the spot Choose a partly shaded, well-drained spot near the garden. In Texas, partial shade keeps the pile from drying out as fast.
2. Build it big enough Make the pile at least 3 feet across. Smaller piles break down much more slowly. Keep stacking until it settles at about 5 feet tall.
3. Start with sticks Lay coarse branches and twigs on the bottom so air can move up through the pile.
4. Layer greens and browns Add 6 to 10 inches of mixed material (dry leaves plus grass clippings or kitchen scraps), then about 1 inch of garden soil or manure to bring in microbes. Repeat the layers.
5. Wet it like a wrung-out sponge The pile should feel damp when you squeeze a handful, but water should not drip out. Water it during Texas summers.
6. Turn it Turn the pile about once a week in summer and once a month in winter. Move the dry outer material into the hot center each time.
7. Run a hot pile to kill weed seeds A well-managed pile should reach 140°F. At that temperature, seeds of most common weeds tested by AgriLife die in under an hour, though black nightshade took about 3 hours.
8. Or start a worm bin For kitchen scraps, a red wiggler bin works on a porch or in a garage. Keep the bedding as moist as a wrung-out sponge and bury food under 1 to 2 inches of bedding.
9. Harvest finished compost Compost is finished when it is dark, soft and crumbly and smells like fresh-dug soil. The layer method takes about 90 to 120 days.

Key facts

• Target carbon-to-nitrogen ratio is about 30:1, which roughly means equal weights of greens and browns (AgriLife HORT-PU-102).
• AgriLife EHT-052 gives a working C:N range of 25:1 to 40:1, moisture of 40-60% by weight, and pH of 6 to 8.
• A hot pile should reach 90-160°F within a few days. The active phase hits 131-170°F within 1-3 days.
• At 140°F, purslane seed takes about 1.3 hours to die and black nightshade about 2.9 hours. At 108°F, pigweed, purslane and barnyardgrass seed are not killed.
• Layer-method compost is ready in about 90-120 days.
• Worm bin: allow 1 sq ft of bin surface per pound of food scraps a week. 1 lb of red wigglers eats up to 2 lb of scraps a week (NC State).
• Worms do best at 59-77°F and survive 32-95°F. Bedding should be about 80% moisture.
• Harvest worm compost at about 4 months.

Texas notes

• Texas heat dries piles fast. Put the pile in partial shade and add water in summer (AgriLife).
• Turn weekly in summer, when the pile works fastest, and monthly in winter.
• A Texas summer can push a worm bin past 95°F, the upper survival limit for red wigglers. Keep bins in shade or move them indoors or into a cool garage.
• Don't compost spring garden plants that had insects or disease. AgriLife's fall garden guide says to remove that residue rather than compost it.