Green Manure: Naturally Enrich Your Garden Soil

As autumn arrives, it’s the perfect time to plan for the next growing season — starting with sowing green manure in your vegetable garden. These plants, often overlooked but making a comeback, play a vital role in improving and preparing the soil. Enriching, loosening, protecting: green manure crops are key to a healthy, productive garden.

What is green manure?

Green manure refers to fast-growing plants sown between main crops to naturally regenerate and enrich the soil. Their main function is to cover the soil, preventing it from being bare, suppressing weeds, and adding essential nutrients. Once sown, these plants grow for several months before being cut and either left on the surface to decompose or incorporated into the soil. This process increases organic matter, improves soil structure and aeration, and enhances water retention.

The benefits of green manure in the vegetable garden

✅ Improves soil structure: Green manure plants like phacelia or rye have deep roots that break up compacted soil, making gardening easier and improving water and nutrient penetration.

✅ Nitrogen fixation: Legumes such as vetch, field beans, or clover capture nitrogen from the air and store it in the soil — an essential nutrient for future crops.

✅ Prevents erosion: Covering the soil during winter protects it from erosion caused by wind and rain while preserving soil life.

✅ Suppresses weeds: By occupying space, green manure prevents weeds from taking hold, reducing the need for weeding before the next planting.

✅ Natural defence against nematodes: Green manures like mustard and phacelia help protect the soil from harmful nematodes that damage plant roots.

✅ Adds organic matter: As they break down, green manures enrich the soil with organic matter, boosting fertility and promoting healthy vegetable growth.

How to choose the right green manure for your soil

The choice of green manure depends on your soil’s needs:

🌱 For acidic soils: Buckwheat is a great option, with strong weed suppression.

🌱 To loosen compacted soil: Phacelia and rye have deep roots that break up hard soil.

🌱 For nitrogen fixation: Crimson clover, field beans, and vetch are ideal legumes.

🌱 To control nematodes: Mustard and phacelia act as natural soil cleansers.

You can combine different green manures for even greater benefits. For example, a mix of rye and vetch makes an excellent winter cover, adding nitrogen and organic matter while improving soil structure.

When and how to sow green manure

🍂 Sowing in autumn: The best time is after summer crops are harvested, between July and October. Choose frost-sensitive varieties like mustard or phacelia — they will die off in winter and form a natural mulch. In spring, you can lightly incorporate the remains into the soil.

🌱 Sowing in spring: If part of your garden remains bare until May or June, sow fast-growing green manures like mustard from March. They will quickly cover the soil and can be cut after 6 weeks.

When to cut and incorporate green manure?

Cut green manure before flowering to ensure maximum nutrients are returned to the soil. Frost-sensitive types will die back over winter, but hardy ones should be cut in early spring. With plants like phacelia or rye, you can incorporate them directly into the soil after cutting to boost organic matter.

Conclusion

Green manures are invaluable allies for keeping your soil healthy, fertile, and ready for future crops. They enrich the soil, prevent erosion, fix nitrogen, suppress weeds, and protect against pests — all while working naturally and efficiently. Autumn is the ideal time to sow these green heroes and ensure a successful growing season.