Choosing No-Till Cover Crops

By Ashleigh Smith

When it comes to growing cover crops, no-till methods are commonly mentioned. But what are they? And what are the benefits? No-till is a method of farming that has risen in popularity as people are increasingly supporting organic growing practices. It focuses on using biological and cultural options for controlling pest populations and improving soil conditions for long-term use of the land. While you can still grow organically and use tilling practices, no-till methods help preserve important soil structure and reduce problems like soil erosion, weed growth, and nutrient depletion that become apparent when a plot of land is grown on for decades and generations.

When soils are tilled, the structure that was created by living organisms, root growth, and developed pore space is disrupted. This isn’t the worst thing when you are using well-developed soil that is lush with nutrients, of good tilth, and rich in organic matter. All of these things allow the soil to drain well, deliver nutrients as needed, and encourage plants to develop healthy root structures. Even with good soil structure, all gardens can still benefit from no-till practices as they reduce soil erosion and encourage soil development rather than reduction. Gardens or farms lacking in these important soil characteristics that are experiencing soil erosion by wind or water, nutrient depletion, compact clay, or empty sand soils would greatly benefit from no-till practices. Doing so will help restore and revitalize spent soils, reduce soil compaction, improve soil tilth, preserve drainage pathways, support microbial activity, suppress weeds, and disrupt pest life cycles.

Want to Know More About How Cover Crops Work?

Check out our article, “What Are Cover Crops and Green Manures Used For?” Or, read our FREE Cover Crop Grow Guide. Both of these resources teach about the different types of plants used as cover crops and what their benefits are. Below we will be diving more into no-till specific topics.

We also recommend checking out the Foglers growing experience with switching to no-till farming as shared by the University of Maine.

Free Cover Crop Grow Guide

No-Till Cover Crop Advantages and Benefits

• Healthy Soil Microbiome
• Prevent Erosion All Year
• Weed Suppression All Year
• Build Organic Matter
• Preserved Soil Drainage Pathways
• Reduce Compaction
• Replace and Scavenge for Nutrients
• Disrupt Pest Lifecycles
• Supports Other Symbiotic Life Cycles

No-Till Cover Crop Disadvantages

• Requires strategic planning, coordination, consistency, and patience.
• Techniques may vary depending on the size of your growing location.
• May become weedy if not terminated properly.
• Takes multiple seasons to establish ideal no-till planting conditions.

Choosing Cover Crops For No-Till Gardens

Spring (Direct Sow and Harvesting)

For benefits to spring-planted cash crops, grow a late summer/fall cover crop intended to winter-kill. The biomass will break down in time for direct sowing when soils are warm enough in the spring. Just be sure to plant close enough to the expected frost dates for the crop to die before it goes to seed. Otherwise, mow or knock down before seed production starts. The frost should then take care of killing the root systems. Popular fall-planted winter-killing cover crops include Peas, Oats, and Radishes.

No-Till, Forage Friendly Mix

Summer (Transplanting and Harvesting)

Cold hardy annuals are great for planting in the fall as they can survive freezing winter temperatures, encourage soil microbe activity through the winter months, and grow vigorously in the spring. Crops like Winter Rye and Crimson Clover are popular. Mow, tarp, rest, and transplant. Allowing the cover crops to start in the fall develops many benefits to the soil microbial activity that occurs throughout the winter and early spring months due to insulated ground temperatures.

All-Purpose Garden Cover Crop Mix

Fall (Direct Sow and Harvesting)

Plant your cover crops in the early spring, knockdown by early summer, tarp, rake mulch into walking paths, then direct sow fall harvested crops. Popular cover crops include Peas and Oats.

Pea and Oat Mix

Support Pollinators

Cover crops aren’t just good for the soil, they are also a great opportunity to support pollinator populations during spring, summer, or fall. As winter approaches, bees and other pollinators are preparing for freezing temperatures by storing enough food to get through the season. This Pollinator Friendly Cover Crop Mix is a great way to assist them during the fall and spring seasons. This mix includes peas, oats, crimson clover, and hairy vetch. The oats, and possibly the peas (depending on your zone) will winterkill. Crimson clover can survive temperatures as low as 0 F and may come back in the spring. However, the peas, oats, and crimson clover are annuals and will not pose a risk of becoming weedy when grown as a cover crop. Hairy vetch is a perennial and is VERY cold hardy. Expect to terminate this cover crop in the spring, even if planted in the fall.

No-Till Pollinator Friendly Cover Crop Mix (Organic)

Terminating No-Till Cover Crops

To terminate a no-till crop, use one of the three natural ways of killing a plant. Either allow the plant to fulfill its lifecycle (while being cautious of reseeding), winterkilling, or starve them of sunlight by cutting and covering. These techniques can also be combined to reach the desired results within specific time frames, all while supporting the natural symbiotic relationship between plants above the surface and microbes living in the soil.

Winter-Killing

This is the easiest and least labor-intensive option. Many plants, like oats, radish, mustard, lentil, and peas, will not tolerate the freezing temperatures of the winter season in most zones. This allows the winter-killed cover crops to be terminated and break down in time for direct sowing in the early spring months.

Crimping

This is the process of knocking down cover crops with a tool such as a flail mower, roller crimper, power harrow, or T-post stomper. Using something that is capable of scratching up the plant matter as it is flattened is preferred by many growers, as this may reduce the amount of time required for tarping.

Tarps

Covering the knocked-down cover crops prevents access to light, water, and air, while increasing temperatures cause stress leading to eventual death and the initiation of decomposition. Tarps should be weighed down to prevent airflow and cooling.

Average Temperature	Days Covered:
50-55 F	18-25
60-65 F	10-15
70-75 F	5-10
Above 80 F	5 or Less

Solarization

Cover a laid-down cover crop with clear plastic. Reusing a used greenhouse cover is best. Solarization kills a cover crop faster than the tarp method because there is more heat being used and added to the system. Results are usually reached faster than tarping and require only a few days (within 2 weeks). However, it may germinate seeds at greater depths and affect soil microbial activity negatively.

Mowing

When mowing or knocking down a cover crop, it is important to allow adequate time for it to grow and approach the flowering stage. Mowing crops such as grains or grasses early on can cause stronger growth as these plants are often adapted to withstand occasional grazing. Allow them to grow up to the milking stage. This is when the seeds have not yet developed and instead release a milky substance from the flowering structure when pressed with a thumbnail. Do not allow them to mature beyond this stage, or it will become a weed.