Build Soil with Green Compost

Whether you’re growing fresh herbs, a large self-sustaining garden, or cutting flowers to make flowers, good, healthy soil is the foundation of productivity. Although we can sometimes buy seeds and organic material and add it to our beds, this is time consuming and expensive. Green manure helps us produce nutrients and organic matter in the environment.

What is Green Compost?

Despite the name, there is no actual manure or animal waste in green manure. Instead, green manure includes fast-growing plants. Often farmers will choose a mix of annual green manure crops.

It is not uncommon to see the phrases cover crop and green manure used interchangeably. Any crop that is grown to cover the soil, rather than being harvested, is called a cover crop. Green manure is a type of cover crop that is added to the soil while the plant is still green and usually beginning to flower.

Some cover crops are left in the field to fully grow. Although these have many benefits, they do not add much nitrogen to the soil. Green manures, especially nitrogen-fixing legumes, add nitrogen to the soil that can be used by future crops.

Hairy vetch adds approx 110 kilograms per hectare of nitrogen when it is grown and it is combined as green manure.

The benefits of green manure are not limited to nitrogen. Here are some good reasons to grow them:

Why Should I Plant Green Manure?

• Suppresses persistent weeds.

• It improves soil microbial activity and provides habitat for beneficial insects.

• It conserves soil and water by protecting soil and reducing erosion.

• It adds organic matter and improves soil structure.

• Help blast hard pans and bring minerals to the surface.

• It improves soil aeration and water retention, allowing plants to grow strong roots.

• It can help break disease cycles in the soil.

How and When Do I Plant Green Compost in My Garden?

In some areas, you can grow green manure year-round. Sometimes farmers plant green manure in the fall and winter so that the beds can rest and protect the soil while not in use. Sometimes, gardeners will sow green manure as part of their summer rotation or to give the bed a quick boost before planting a fall crop.

Most green manures will need 8 weeks to grow (maybe longer over winter) and 6 weeks to decompose before the bed is ready for replanting.

Growing green manure crops is easy! Generally, your green manure crop should come with a specific set of sowing instructions, but there are basic guidelines that will work for most.

You need to start with bare ground. Then you can spread your crop. Work the seeds into the soil lightly, to keep them moist and help protect them from birds.

If you plant in the fall and winter, there may be enough rain for your seeds to grow and flourish. In the summer months, you will probably need to stop watering or pull the sprinkler.

In the deep summer of the southeast, sprouting any crop can be a big challenge. Starting cool-season green manures in late summer and early fall can be very difficult.

Placing cardboard over the bed before planting can help hold moisture and shade the soil until you are ready to plant. You can also use shade cloth over your green manure if you have germination problems.

Our Favorite Green Manure Plants

The amount of green manure you choose for your garden will depend on your soil and needs. You will also need to choose a plant that is suitable for the season. You can think of green manure crops as either warm season or cool season.

Any nitrogen-fixing crop is marked *.

Warm Season Green Manure Plants

These plants are ideal for spring or summer planting to help build soil in bare beds throughout the season.

Buckwheat and Sunn Hemp are fast growing options.

Cold Season Green Manure Plants

This green manure is suitable for planting in autumn or winter. They can help add fertility and protect the soil in winter.

Daikon radishes are a great choice for breaking up compacted soil. In general, we recommend that white clover in your planting beds be kept as a cover crop for at least a year, as part of a larger rotation. And it’s a good choice of methods.

How to Add Green Manure Plants to the Soil

After 8 weeks or so, your green manure crop should be well established and almost ready or beginning to flower. At this stage, your green manure should be full of nutrients that you can return to the soil.

Don’t let your green manure crop ripen and go to seed. The seed can take up to 90% of plant nitrogen.

Nitrogen is used to make protein in seeds. If nitrogen is used to make seeds, it is not available for your next plant.

The most common method of dealing with green manure crops is to rototill the plant in the bed either with a tractor or a small rototiller. Depending on the crop, you will probably need to mow it first, either with a tractor or a mower. In small beds, mow or cut your crop, then dig into the soil with a shovel or garden fork.

Of course, many farmers will practice no-till practices. If you don’t want to till your green manure, you can cut it up and let it break down on the ground. It will double as mulch, and you can transplant directly into it.

If you’re in a hurry to plant, covering your mulch with tarps or plastic can help speed up the decomposition process. It holds moisture in the plant and soil and earthworms and other insects will move around under the tile, helping to break down the green manure.