Once you’ve finished cleaning up your vegetable beds, it’s time to consider planting a cover crop. Cover crops, sometimes called “green manure” crops, are planted to maintain and improve soil structure, soil fertility and to protect the living portion of your soil, including micro-organisms.
In the past, once the gardening season ended, we cleared away crop remnants and left the soil bare through winter. The thought was that the garden needed to rest. What we’ve learned however, is that ground protected through the off season is ground that is much more productive when the season rolls around next spring.
The most effective way to protect your soil is to plant a cover crop. Cover crops perform several functions including increasing soil organic matter, fixing nitrogen, breaking up compacted soils, suppressing weeds, acting as a living mulch, promoting, and protecting valuable soil microbial activity.
Though often referred to as “green manure”, cover crops are the actual plants. They become green manure, once they are turned into the soil. Cover crops fall into two categories: legumes and fast-growing grasses.
Both categories will add organic material to the soil, but legumes bring the added advantage of nitrogen fixing. The term nitrogen fixing refers to the plant’s ability to convert nitrogen from the air into a form useable by plants. When the cover crop is worked into the soil, the nitrogen is released and becomes available for crops that are planted in the area.
Red clover (Trifolium pratense), Crimson clover (Trifolium carinatum) as well as White clover will work to protect the soil and fix nitrogen, as will fava beans and hairy vetch.
Fast growing grasses are planted to add organic material as well as improve soil tilth and structure. They do this by creating biomass.
This includes buckwheat, oats, and winter rye. These grasses develop deep root systems which help aerate and reduce compaction, as well as protect soil microorganisms.
The time to plant a cover crop is as you finish harvesting and clear your crops. Cover crops can be planted in portions, which makes it easy to start putting down seed even as other parts of the garden are still producing. Simply rake up the soil with a bow rake, scatter the seed by hand, then cover lightly.
Cover crop seeds will germinate quickly in the warm soils of late summer, early fall. The key is to keep the seed moist. Cover crops require little maintenance, once germinated. The main thing to watch for is to make sure the crop doesn’t go to seed.
In the spring, the crop needs to be terminated. This can be accomplished by cutting down the crop with a mower or weed trimmer, or by digging it in with a garden fork or hoe.
Cover crops are well suited for all gardens, both in-ground and raised beds. They provide cover and stability for your soil through the winter months and help improve soil structure and fertility for the spring and summer garden.
