Turning Cover Crops into Green Manure

Introduction: Understanding Green Manure and Spring Cover Crops

Knowing what to do with cover crop in spring is key to maintaining healthy, fertile soil. As temperatures rise, your spring cover crops—whether planted last fall or early spring—begin rapid growth. The next step is to turn them into green manure, an organic way to boost soil health and fertility.

Green manure refers to cover crops like winter rye, annual ryegrass, and leguminous species such as hairy vetch that are grown specifically to be cut down and returned to the soil. These cover crops and green manures naturally improve soil structure, retain moisture, suppress weeds, and fix nitrogen—all without synthetic inputs.

To see the process in action, check out our Green Manure How-To Video.

For a broader overview of cover crop benefits, species, and seasonal timing, read our Introduction to Cover Crops – A Growing Guide and browse our full Cover Crops Collection.

Benefits of Green Manure in Spring Gardening

Incorporating green manure into your gardening routine has long-term benefits for soil health and productivity. Whether you garden till or follow a no tilling gardening approach, turning spring cover crops into green manure enhances your soil in the following ways:

• Improves soil fertility by adding organic matter and fixing nitrogen (especially with legumes)
• Prevents erosion by shielding the soil from wind and rain
• Suppresses weeds by blocking light and competing for nutrients
• Increases water retention by improving soil structure
• Encourages beneficial microbes and insects

If you’re exploring how to use cover crops in a no till garden, green manures can be a foundational strategy. For summer applications, check out The Essential Guide to Summer Cover Crops and our blog on Growing Cover Crops in Summer.

You can also shop for specific soil-building varieties in our Green Manure Seeds Collection.

When to Cut Cover Crop

Timing matters. Knowing when to cut cover crop ensures you're getting the most out of its biomass and nutrient value.

• Cut before the crop goes to seed. If it sets seed, you risk weed problems later.
• The ideal time is when about 50% of the crop is flowering—this is peak biomass.
• Wait 3–6 weeks after cutting before planting your next crop. This allows decomposition and prevents temporary nitrogen lock-up.

Need inspiration? Our full Cover Crops Blog is packed with tips and timing guides for different zones and plant types.

Techniques for Turning Cover Crops into Green Manure

1. Tilling Cover Crops

The most straightforward method is to till the cover crop into the soil. This breaks it down rapidly, turning the organic matter into nutrients for your next crop.

• Pros: Fast decomposition, less nitrogen lost to the atmosphere.
• Cons: Disturbs soil structure; doesn’t provide weed suppression or mulch while decomposing.

Use a rototiller or disc harrow for large areas. Read more about this process in our guide on Tilling Cover Crops.

2. Mow and Mulch (No-Till Gardening Method)

In no till gardens, mow or cut the crop and leave the residue on the soil surface as mulch.

• Pros: Conserves moisture, suppresses weeds, supports soil organisms.
• Cons: Slower decomposition, may not kill some cover crops completely.

To get started with no tilling gardening, visit our full No-Till Gardening Guide.

3. Cut and Compost

Cut your cover crop with a hand sickle, weed-eater, or scythe, compost it, and return it to the soil.

• Pros: Produces nutrient-rich compost over time; ideal for raised beds.
• Cons: More labor-intensive and takes longer (several months).

Pair this with our Bark Mulch (2 cu ft) for extra moisture retention and weed control.

4. Rolling or Crimping

Use a roller or your tiller (with tines off) to flatten cover crops.

• Pros: Minimal soil disturbance; useful in no-till systems.
• Cons: May not fully terminate the crop, especially aggressive species.

Tools and Equipment for Cover Crop Management

Whether you’re cutting, mowing, or tilling, using the right tools can make your job easier and more effective.

Recommended Tools

For Large Plots or Fields:

• Flail mowers – Great for chopping large biomass into fine mulch that decomposes quickly.
• Rotary mowers – Effective for managing thick or tall cover crops like rye and vetch.
• Disc harrows and rototillers – Ideal for incorporating biomass in garden till systems.

For Small Gardens or Raised Beds:

• Hand sickles and scythes – Traditional tools that give precise control in small spaces.
• Weed eaters – Fast and accessible option for mowing cover crops in home gardens.
• Compost forks and garden carts – Helpful for managing composted cover crops.

Browse our Tools & Equipment Collection to find exactly what you need for your space and scale.

Safety & Maintenance Tips

Managing equipment responsibly ensures both your safety and the longevity of your tools:

• Wear PPE: Use gloves, goggles, ear protection, and closed-toe shoes when operating powered tools.
• Pre-check your tools: Inspect for loose bolts, dull blades, or frayed belts before each use.
• Clean after use: Remove dirt and plant residue, especially from tiller tines and mower decks.
• Lubricate regularly: Follow manufacturer guidelines for oiling blades and bearings.
• Store tools properly: Keep them in a dry, sheltered place to avoid rust or weather damage.

Following these best practices will keep your tools performing well throughout the seasons.

Conclusion

By turning spring cover crops into green manure, you build rich, resilient soil for the growing season ahead. Whether you’re tilling cover crops into the ground or exploring how to use cover crops in a no till garden, the results are the same: enhanced fertility, improved soil structure, and fewer weeds.

Explore related resources and products:

• Watch: Green Manure Video
• Shop Green Manure Seeds
• Explore Cover Crops & Guides

Your soil—and your future harvests—will thank you.

Grow Organic. Grow Smart.

FAQs: Green Manure and Spring Cover Crops

• What to do with cover crop in spring?
  • You should cut it down before it goes to seed, then either till it into the soil, mulch it in place, or compost it—depending on your gardening system and timing.
• When to cut cover crop?
  • Cut it when about 50% of the crop is flowering to get the most biomass and nutrient value. Avoid letting it set seed.
• Can I use cover crops in a no till garden?
  • Absolutely. Mow or roll the cover crop, leave it as mulch, and let it decompose naturally.
• How long should I wait to plant after turning under a cover crop?
  • Wait about 3 to 6 weeks. This allows the green manure to decompose and prevents nitrogen tie-up.
• What’s the difference between tilling and no-till methods for cover crops?
  • Tilling incorporates the crop quickly for faster decomposition, while no-till methods preserve soil structure and moisture but take longer to break down.

Resource Area:

Cover Crop Fundamentals

Discover how cover crops—including vetch—improve soil structure, suppress weeds, and support soil life:

• Cover Crops – Comprehensive overview of when, why, and how to use cover crops for soil benefits.
• Nematodes in Soil: The Invisible Threat to Your Plants – Understand how beneficial soil life like cover crops can help manage destructive nematodes.

Vetch in Crop Rotation

Explore how including vetch or other legumes can enhance crop health and prevent soil erosion:

• Companion Planting for Thriving Bean Crops – Insights on using vetch and beans together to improve soil fertility and structure.
• Planting Vetch for Soil Structure Enhancement – Shows how rotating with vetch builds better root zones and reduces compaction.