Updated: March 12, 2025
By Sarah Hirsh , Haley Sater , and Dwayne Joseph
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FS-2024-0743  |  March 2025

Cover Crop Planning

By Sarah Hirsh, Ph.D., Haley Sater, Ph.D., and Dwayne Joseph, Ph.D.

A graphic featuring interconnecting circles representing three primary considerations for cover crop planning: the purpose of cover crops (in blue), the appropriate cover crop window (in red), and farmer expectations (in yellow).
Figure 1. Three primary considerations for cover crop planning (Image credit Sarah Hirsh).

Cover cropping is a conservation practice intended to “cover” the land when it is not being used for the primary purpose of growing “cash crops.” See FS-2023-0692, Introduction to Growing Cover Crops in the Mid-Atlantic. Cover crops can provide various benefits, such as preventing soil erosion, scavenging nutrients, building soil organic matter, or controlling pests such as weeds. Since cover crops are not a primary source of farm income, farmers may spend less time planning and managing them when compared to their cash crops. Cover crops may be perceived as a one-size-fits-all bridge between the cash crops, with the same cover crop used regardless of other system factors. However, all cover crops are not equal. Different cover crops can be used for different purposes. Evaluating the entire system (cash and cover crops) is a critical step in choosing the most beneficial cover crop. Cover crop planning can greatly increase the benefits that cover crops provide, making the overall farming system more productive, sustainable, and profitable.

Planning can help farmers get the most agronomic and economic value from their cover crops. It is important to recognize that all cover cropping involves a certain level of financial investment and risk. Unlike some other conservation practices that actually require less financial input, e.g., no-till, cover cropping involves financial investment in seed, planting and termination. However, there is no guarantee of a payback. Putting extra effort into planning cover crop systems increases the likelihood of getting a return on investment and yields greater benefits for both the field and the farmer.

Cover crop planning involves thinking logically and in-depth about how cover crops can fit in the overall cropping system, including how cash and cover crops fit together. Some key questions include: 

  • How will the cover crop fit into the cash crop rotation?
  • Could the cash crop rotation be modified to facilitate a more effective a cover crop?
  • How is the cover crop likely to affect the cash crop in positive or negative ways? 

While not harvested for cash, cover crops can greatly contribute to the ecological functions of the land and the profitability of subsequent cash crops. However, appropriate cover crop selection and management are required to realize these potential benefits of cover cropping. In cover cropping, being innovative and exploring new practices can be beneficial, but careful planning for experimentation with new practices or species helps ensure calculated risk-taking.

While innovation and exploration can be rewarding, farmers can reduce risks by planning that includes three basic considerations: 1) cover crop purpose, 2) cover crop window, and 3) farmer expectations (Figure 1). Farmers can design cover crops while considering these three aspects concurrently. After the farmer has identified their purpose, window, and investigated what expectations might be realistic for the cover crop, they can choose the best cover crop species and management practices.

Buckwheat cover crop smothering weeds.
Figure 2. Buckwheat might be grown as a summer cover crop that quickly smothers weeds and encourages pollinators on a vegetable operation (Photo credit Thelonius Cook).

The purpose or reason for using the cover crop should be clearly identified for each particular field. What specific outcomes are trying to be achieved or improved by planting the cover crop? 

Some potential cover crop purposes include:

  • Preventing soil erosion
  • Scavenging nutrients
  • Building organic matter
  • Alleviating compaction
  • Encouraging beneficial insects or pollinators
  • Adding nitrogen to the system
  • Controlling pests such as weeds 

No single cover crop will meet all of these purposes. As a rule of thumb, it is best to focus on one or two purposes. Different cover crop species and management practices should be employed depending on the purpose(s) of the cover crop (Figure 2).

Cover crops typically fit in a “window” of time between cash crop growth periods. In some cases, a cover crop growth period can overlap with the cash crop growth period. For example, a cover crop can be interseeded into a standing cash crop, or a cash crop could be planted into a standing cover crop (sometimes referred to as “planting green”).

A bar graph displaying the spring biomass accumulation of rye cover crops based on different termination dates. Each bar represents the biomass measured at specific termination times, illustrating the variations in growth and accumulation.
Figure 3. Rye cover crop spring biomass accumulation for various termination dates (Stefun and Weil, unpublished).

Both the length and timing of the cover crop growing window are critical factors in determining how well and how much the cover crop will grow. The cover crop needs enough time to establish and accumulate biomass, but it also needs favorable growing conditions. If the majority of the cover crop window is during the winter season with cold weather and short days, the weeks of growth time in the fall (after planting) and spring (prior to termination) can have a disproportionately large impact on how effectively that cover crop functions. For example, extending the cover crop season two weeks later can greatly increase the amount of spring cover crop biomass, and in turn greatly increase the benefits provided by that biomass such as contributing organic matter and serving as a mulch (Figure 3; Stefun and Weil, unpublished). Extending the cover crop season by planting earlier can greatly increase other benefits of the cover crop such as decreasing winter nitrate leaching (Sedghi & Weil, 2022). While extending the cover crop growing season is important, certain cover crops can compete for resources or have other negative implications for following cash crops. For example, a mature cereal rye cover crop will immobilize (tie up) nitrogen, which could impede early season growth of a following corn crop.

An excellent first step in planning is to diagram the existing cash crop rotation, using a grid similar to the one in Figure 4. This will show the gaps or windows of time between cash crops where cover crops can fit. The most basic approach is to then insert cover crops into those open windows. The selected cover crop species should be suitable to the planting and termination timing of the window. For example, in Maryland, if the cover crop window starts November 1 and ends April 15, a forage radish would not be an appropriate cover crop for scavenging nutrients, as forage radish has weak cold tolerance, and little growth and scavenging potential when planted after October 1. Cereal rye would be a more appropriate cover crop, since it has strong cold tolerance and would have an opportunity to grow in the spring.

A diagram showing the existing rotation of various crops and the diagram is showing existing gaps and sticking points to determine rotations.
Figure 4. Example of how to visually plan cash and cover crop rotations (resource developed by Chris Lawrence, VA NRCS).

The problem often arises that cover crops cannot meet the desired purpose within the available window. This is a “sticking point,” or an issue within the crop rotation that blocks the insertion of an appropriate cover crop (Lawrence, personal communication). Cash crop rotations can be adjusted or changed in order to eliminate “sticking points” or expand cover crop windows. On first thought, it may seem unrealistic to change the cash crop rotation in order to fit a better cover crop. After all, the cash crop is the bread and butter of the farming enterprise. However, cover crops do require financial inputs and can result in short- and long-term financial gains. Therefore, some modifications to the cash crop rotation can actually pay off. Modifications to the cash crop will be site-by-site specific, but below is one example:

This field follows a corn-soybean rotation on the Eastern Shore of Maryland. The field has sandy soils, low organic matter, and tends to need high nitrogen inputs. The corn is typically planted on April 15 and harvested October 1. Soybean is typically planted on May 10 and harvested November 1. The farmer would like to plant a cover crop mix including a legume ahead of corn. However, only grass species cover crops are recommended to be planted after the late harvest of soybean. In order to plant an earlier mixed cover crop, the farmer changed his crop rotation to corn-corn-soybean-soybean from the traditional corn-soybean-corn-soybean. The first year of corn was planted April 1, and harvested September 20, at which time a crimson clover/forage radish/ triticale cover crop was planted. Late September is an ideal planting window for that cover crop. The cover crop was able to grow robustly, and serve its function of fixing nitrogen and accumulating biomass. The cover crop was terminated April 15, at which time the second year of corn was planted. The corn benefited from the nitrogen inputs from the cover crop. The corn was harvested October 1, at which point a cereal rye cover crop was planted. The cereal rye cover crop preceded soybean, and therefore nitrogen immobilization was not a concern, nor was there a need for the cover crop to fix nitrogen. The cereal rye did serve as a desirable mulch layer beneath the soybean and helped to reduce weed pressure.

heat + vetch cover crop aerially seeded into standing soybean.
Figure 5. Wheat + vetch cover crop aerially seeded into standing soybean. The cover crop was seeded in September allowing it to begin growing prior to the November soybean harvest (Photo credit Sarah Hirsh).

As with cash crops, cover crop stand and performance will be better when seeds are planted directly into the soil. However, sometimes modifying cash crop rotations to fit more functional cover crops (as discussed in Example 1) is not a viable option. Depending on the primary purposes for the cover crop, aerially seeding cover crops into a cash crop may or may not be a viable alternative (Figure 5). For example, aerial seeded cover crops are much more likely to have an uneven stand. If cover crops are being used to prevent soil erosion, an uneven stand will not be too detrimental. On the other hand, if the purpose of a cover crop is to fix atmospheric nitrogen, and therefore allow the farmer to reduce nitrogen inputs to the following cash crop, an uneven stand will be very problematic; the farmer would not be able to reduce nitrogen inputs since the nitrogen additions from the cover crop were so uneven.

While it is important to be innovative and try new practices, farmers should be informed and realistic about their expectations for cover crop biomass accumulation, height, and plant characteristics. For example, a vetch cover crop has a robust, vining growth habit, whereas clovers will be shorter and not vining. Within the same growing season, wheat will be shorter than triticale, which will be shorter than cereal rye.

It is also important for farmers to have realistic expectations for themselves and their operation. During the planning process, they should evaluate whether they have the resources, capacity, and equipment to implement the cover crop system. For example, does the farmer have the equipment to manage a late-terminated vetch crop (Figure 6)?

n planter with “shark teeth” was able to cut through waist-high stand of hairy vetch (Photo credits Haley Sater (vetch) and Sarah Hirsh (equipment)). Alt text: Corn planter with “shark teeth” was able to cut through waist-high stand of hairy vetch.
Figure 6. Corn planter with “shark teeth” was able to cut through waist-high stand of hairy vetch (Photo credits Haley Sater (vetch) and Sarah Hirsh (equipment)).

Expediency and precision need to be balanced when implementing cover crops. With cover crop planning that addresses the three basic considerations, farmers will likely implement various cover crops across a single farm, according to differences in conditions such as crop rotations, soils, or field history. However, farmers may decide to compromise this precision according to their resources, management capacity, and equipment.

Planting a cash crop into a standing cover crop (“planting green”) can be an excellent way to extend the cover crop growth window, and therefore increase the cover crop benefits. However, cover crops can significantly increase biomass during spring growth (see Figure 3). The farmer needs to be aware of the cover crop growth potential, and have the ability and equipment to plant their cash crop into it. Having realistic expectations of the cover crop growth will allow the farmer to choose appropriate species based on available equipment and resources.

Farmers should choose the cover crop species, seeding rates, and planting and termination methods based on the cover crop purpose, window, and on realistic capacity of the farm and farmer. When thinking about these factors first, the list of appropriate species greatly narrows. For example, the farmer may have a purpose of fixing nitrogen with a legume, but furthermore, wants a small seeded legume that can be broadcast seeded, and a legume that has a non-vining and shorter stature growth habit if terminated later in the spring. These criteria shorten the list of potential species; however, crimson and balansa clovers would both fit these criteria (Figure 7). Consult the resources below for specific species characteristics and growth tolerances.

Crimson clover (left) and balansa clover (right)
 Figure 7. Crimson clover (left) and balansa clover (right) (Photo credit Sarah Hirsh).

During the cover crop planning process, consider the following recommendations:

  • When diagramming the crop rotation, note the functional groups of the cash crops (e.g., grass, legume, brassica). When possible, rotate functional groups between the cash and cover crops. For example, if growing brassica cash crops, consider a grass and/or legume cover crop. If growing corn as a cash crop, a cover crop that includes other functional groups would be worthwhile.
  • Even if a cover crop seems to be a good fit based on your research or input from peers, try “new to you” practices on a smaller area first.
  • Try “new to you” practices for multiple years, especially if variables such as weather appeared to have hindered or helped the cover crop.
  • Consider narrow fits. Maybe a particular cover crop is not a good fit on most of the farm, but there is one field (even if it is small acreage or marginal land) where that cover crop would be beneficial.

In summary, farmers should implement cover crops to meet a particular purpose. The cover crop growth window will greatly influence how well cover crops achieve their purpose. Farmers should be realistic about what to expect for particular cover crop species and growth periods. Cover crops can enhance the sustainability and profitability of the entire farming system when intentionally planned and managed.

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