Composting your steer and horse manure for garden results

I this question on one of our YouTube videos on making manure tea, and I thought I’d provide the answer here with some detail, and write a whole post.

Introduction
Fresh manure is a valuable organic resource for gardeners, but it needs to be handled with care. Applying it straight to your beds can burn plants, introduce harmful bacteria, and leave you with a garden full of weeds. The solution? Age your manure properly. In this guide, we’ll walk through how to transform raw manure into safe, nutrient-rich compost your garden will love.

Why You Should Age Manure
Before diving into the how-to, it’s important to understand why aging manure is necessary. Fresh manure may contain pathogens, high levels of nitrogen, and viable weed seeds. Letting it break down over time—through a process known as composting or curing—eliminates these issues and maximizes its garden benefits.

• Kills Pathogens – Proper composting eliminates harmful bacteria like E. coli and Salmonella.
• Reduces Weed Seeds – Heat and time destroy seeds that may sprout in your garden.
• Prevents Burning Plants – Fresh manure is high in nitrogen and can “burn” tender roots and foliage.
• Improves Soil Structure – Aged manure helps soil retain moisture and supports beneficial microbes.

Step-by-Step: How to Age Manure
Now that you know why aging is important, here’s how to do it properly. Whether you’re working with cow, horse, chicken, or other livestock manure, the basic method remains the same.

1. Choose the Right Location
Select a space where your manure pile won’t contaminate water sources or nearby edible crops. A compost bin, enclosed area, or open pile on bare ground all work well. Just make sure it’s well-drained and accessible for turning.

2. Mix With Carbon-Rich Browns
Manure on its own can become compacted and smelly. To keep your compost pile balanced and healthy, mix it with carbon-rich materials like straw, shredded leaves, or sawdust. This not only reduces odor but helps create the ideal conditions for decomposition. Aim for a ratio of about 1 part manure to 2 parts brown materials.

3. Maintain Proper Moisture
A good compost pile should feel like a wrung-out sponge—not soggy, not dry. Add water as needed and consider covering your pile during heavy rains. Maintaining the right moisture level is critical for microbial activity.

4. Turn Regularly
Aeration helps your pile decompose efficiently. Every 1–2 weeks, turn the pile with a garden fork or compost aerator to introduce oxygen. This keeps things hot, active, and reduces odors while speeding up breakdown.

5. Let It Cure
Once the pile has composted actively for about 6–8 weeks, let it rest. Curing for another 3–6 months allows any remaining unstable compounds to mellow out. The finished product should be dark brown, crumbly, and smell earthy.

6. Test Before Use
Not sure if your manure is ready? Do a simple germination test. Plant a few quick-growing seeds (like radish or lettuce) in the compost. If they sprout and thrive, the manure is safe for use in the garden.

When to Apply Aged Manure
Timing matters—especially for food crops. Apply aged manure to vegetable beds at least 90–120 days before harvesting anything that touches the soil. For flower beds, shrubs, and trees, you can use it year-round as a top dressing or soil booster.

Master Gardener Tip
Always think of aging manure like aging fine wine—time and balance make all the difference. Rushing the process risks harming your plants and your soil health.

Conclusion
Aging manure isn’t complicated, but it does take patience and care. By following the right steps, you’ll create a powerful amendment that enriches your soil, reduces waste, and supports a thriving garden. Treat your soil well, and it will reward you tenfold.