Terminating Cover Crops

With cool-season vegetable crops going into the ground, many gardeners who ventured into cover cropping last autumn may ask a familiar question: What do I do now? Their crops have fulfilled their purpose –anchoring the topsoil, retaining soil moisture and biome, and fixing nitrogen into the ground. However, with planting season upon us, it’s time to address the thatchy mat of beneficial crops that need removal for new planting.
First and foremost, it's crucial not to delay! While cover crops offer numerous benefits to a vegetable garden, they can go to seed when left unattended, ultimately creating a massive seedbed in the soil that will require mitigation efforts throughout the growing season. The risk of this is exceptionally high with grassy cover crops, such as winter rye, annual rye, wheat, barley, and oats, as these crops develop deep root systems over the winter, allowing them to utilize spring moisture and heat quickly. You can prevent this potential issue and maintain control over your garden by acting promptly.
Then, there is the matter of how the benefits of some cover crops are not fully realized until they are incorporated into the soil. With nitrogen fixers, specifically (including hairy vetch, various clovers, and other legumes), the majority of nitrogen contributed to the soil takes place when the leafy masses of the plants are, by one method or another, returned to the ground. While some nitrogen is released from their roots while growing, a much more notable amount is made available as a whole plant decomposes.
A few different methods are utilized to incorporate cover crops, and the ones to choose will largely depend on the crops present, the effort required, and the methods a gardener is willing to utilize. Crimping is the process of severing a crop at the base and laying it over to create a decomposing thatch/mulch layer for the garden without disturbing the soil. Mowing provides similar benefits but produces more finely chopped mulch with smaller particles, ultimately leading to quicker breakdown. Tarping, then, smothers the plants and utilizes trapped moisture and heat to accelerate degradation.
For the more hands-on approaches, working the soil and tilling remain options for quick turnaround. However, these methods should be utilized sparingly. Every time a soil profile is disturbed, its aggregates are broken down, its beneficial fungal system is pulverized, and the overall microbiome is left less beneficial than it would be otherwise. Over time, excessive tilling leads to eroded and diminished topsoil, polluted waterways, and ultimately less-vigorous crops and harvests.
And don’t forget to consider which crops will take their place! Heavy-feeding crops like broccoli, cauliflower, and cabbage thrive in nitrogen-fixed soil. Crops with shallow roots like lettuce, radish, beets, and various herbs are great candidates for a garden bed with a thick thatch layer that slowly breaks down and feeds the soil. Cover cropping is most successful when we consider its benefits and pair them with crops that can utilize those benefits the most.

by Anthony Reardon, Horticulture Small Farms Agent 2025