Crop Rotation Planning: A Natural Way to Reduce Pests and Disease
What if you could grow plants in a way that naturally boosts their pest and disease resistance? Sounds pretty amazing, right?
Plants are better able to protect themselves when they are grown in healthy soil. Unfortunately, many conventional farming and gardening practices do not promote healthy soil – or more accurately, they don’t promote healthy soil ecosystems that are essential for growing healthy plants.
Pests and disease are nature’s way of culling weak or sickly plants. Therefore, pests and disease should be thought of as a symptom of a problem rather than the actual problem.
Our job as gardeners and farmers is to provide healthy soils that are rich in organic matter and that support a diverse soil ecosystem.
To do this we need to recognize that healthy plants are part of a vibrant underground bartering system that rely on their allies in the soil, including beneficial bacteria and fungi, to exchange key nutrients. These symbiotic partnerships are severed when we use fast-acting fertilizers to feed the plant instead of the soil. These fertilizers provide an overabundance of a limited number of nutrients (typically N-P-K) that shuts down a plant’s need to barter – thus denying them access to other vital nutrients not provided by the fertilizer. These high octane fertilizers also create a feeding frenzy that consumes organic matter, further depleting the soil and degrading the soil ecosystem.
In summary, healthy plants require healthy soils teeming with diverse soil life that in turn help reduce pest and disease problems.
Great! Now how do we promote healthy soils?
Building organic rich soil is essential for supporting healthy soil ecosystems. Yet it is not something that happens overnight. Natural fertilizers such as leaves, plant residues, and manure break down slowly, gradually releasing their nutrients in a way that soil organisms can capture and efficiently use without creating negative downstream effects that are typical with chemical-based fertilizers.
The basics for regenerating healthy soils are:
1) Adopt no-till techniques -- tilling reduces organic matter as well as disrupts and/or kills soil organisms, especially the important mycorrhizal fungi
2) Keep soils covered with mulch, crops, and/or cover crops -- bare soils are susceptible to wind and water erosion, increased evapotranspiration losses, and large temperature swings that negatively impact soil organisms
3) Rotate crops -- the greater the diversity of crops the better to support a more diverse soil ecosystem
Utilizing all three practices will improve soil health as well as reduce problems with pests and diseases. For now, we will focus on crop rotation while also touching on the issue of intercropping (a form of cover cropping while your main crop is still growing).
Crop Rotation 101
Crop rotation is one of the oldest agricultural practices and is easy to implement. Rotating crops allows us to continuously grow food, fiber, or forage on the same plot of land by systematically rotating set groups of plants in different areas each year. For smaller plots of land such as gardens, the crops may be annual vegetables, herbs, and/or flowers. For larger operations it may include rotating cultivated crops, grain crops, and grass or sod crops.
It does take some upfront work to develop a crop rotation plan that is suited to a specific piece of land, production needs, climate, etc. The tricky part is usually deciding what to group together and what should proceed or follow what. There are many ways to go about this, which offers plenty of flexibility but can be overwhelming when first creating your plan.
But first, why bother with crop rotation?
Maintaining and rebuilding healthy soils is important for the health and longevity of our society since our own existence is dependent on the often overlooked but essential functions provided (for free) by soil organisms. These functions include sustaining life, regulating how water moves over and through a watershed, filtering and detoxifying pollutants, cycling nutrients, etc. Healthy and intact soils are far more resilient and will be even more important as we work to mitigate and adapt to climate change.
Thus, when crop rotation is combined with other regenerative practices, it allows us to sustainably grow crops in the same area while also improving soil health, optimizing nutrients in the soil (ensuring more nutrient-dense foods), and reducing pest and weed pressure.
No one practice is going to completely eliminate pest issues, but a diverse multi-year crop rotation will go a long way to promoting optimal growing conditions that in turn will make your plants more resilient with minimal human intervention.
Developing a three or ideally four year crop rotation is the minimum amount of time recommended to reduce soil-borne pests and diseases to harmless levels before the same crops should be grown in a particular location again.
Part of the beauty of developing a crop rotation plan is that all of the thinking is done up front, usually during the slower winter months. That means that during the busy planting or transplanting season, you simply need to follow the plan (while still observing and making tweaks as necessary)!
Since rotating crops is one of the oldest agricultural practices, there is no shortage of information available to help get you started. I found Jean-Martin Fortier’s book The Market Gardener and Eliot Coleman’s book The New Organic Grower to be especially helpful for our small-scale, regenerative farm.
Below our two example crop rotations that we have used or developed and plan to use this coming growing season.
Example 1: Four-Bed Crop Rotation Plan
I began using a simple four-year/four-bed crop rotation plan over a decade ago in our urban backyard garden (Zone 4b). My initial goals were to grow enough food to feed myself and my husband during the growing season while preserving surplus food for the winter months.
This four-bed crop rotation plan divided plants into four primary groups:
Leaf crops > Fruit crops > Root crops > Legume crops
This plan ensured that each crop would have four years before it was grown in the same location, thus reducing the ability for pests preferring specific plant families to build up in sufficient numbers in any one bed.
Rotating crops between equally sized beds is ideal but as I found out, it is possible to rotate groups in multiple beds of various sizes as long as you are willing to adjust what you grow from each group as you cycle them through the various beds.
For example, we had six different hugelkultur raised beds that varied significantly by size, shape, and microclimate – from the skinny long beds along our fence (and partially under a mature crap apple tree) to more conventional and significantly larger rectangular beds located in nearly full sun.
I did my best to divide these into four equal(ish) sized beds that I dutifully rotated crops through. It was challenging to grow certain crops in certain beds, such as sun and heat loving tomatoes in our shady fence beds (those years I often grew tomatoes in containers that I could keep in the sun or move into our greenhouse). I made it work by adjusting what I grew from year to year to match the specific growing conditions of each bed and plant group.
Example 2: Eight-Bed Crop Rotation Plan
Heading into the 2021 growing season (Zone 5b) – our first year operating a market garden – I decided to revisit our crop rotation plan to better reflect our larger garden area as well as our changing production goals.
Unlike our urban hobby garden, our current garden is not a jumble of beds built over several years as we gradually converted our backyard into an edible landscape. We instead built a keyhole-style hugelkultur garden that could easily be split into eight beds and thus an eight-year crop rotation.
Unfortunately, I planted our perennial asparagus bed in 2020, before I decided to revise and expand our crop rotation. At the time I didn’t worry that our asparagus bed ended up a little larger than planned and simply planted more seedlings to one side. In my interest in setting up beds of equal size, the off-center asparagus bed means that our eight-bed configuration is not as uniform as I had hoped when I originally designed the keyhole garden.
Unfortunately in our first year implementing this new plan we will need to break the four-year rule. Before deciding on the plan listed below, I mapped out different rotations and unfortunately with where certain crops were grown in 2020 and where I planted garlic for 2021, I had to compromise and keep our potato crop (roots #2) in the same bed two years in a row. Granted I won’t be growing potatoes in the same exact location within that bed, but this back-to-back planting will benefit the potato beetles that will appreciate having their food source grown in the same general area. As a result, I will also be growing fewer potatoes this year which leaves extra room in that bed that I will use to grow peas.
After several iterations, here is our updated eight-year crop rotation plan:
Bed 1: Roots #1 (carrots, beets, parsnip, turnip, radish)
Bed 2: Greens (sorrel, arugula, Asian greens, kale, swiss chard, lettuce, spinach) + compost
Bed 3: Roots #2 (potato, rutabaga, kohlrabi) + peas (2021 season only)
Bed 4: Squash (cucumber, zucchini, summer and winter squash) + compost
Bed 5: Brassicaceae (cabbage, broccoli, cauliflower, brussel sprouts)
Bed 6: Liliaceae (garlic, onion, leek, shallot) + compost
Bed 7: Solanaceae (pepper, eggplant, tomato)
Bed 8: Legumes (peas, beans) + brassicas (broccoli and chard or kale) + compost
Asparagus Bed (permanent bed)
I have no doubts that in the coming years I will continue to tweak this plan, especially as we learn more with intercropping various companion plants and cover crops.
Other Considerations: Companion Planning and Intercropping
There are plenty other considerations that can be factored in when developing a crop rotation plan. However, it is better to get started with something and refine it as you get more experience than to get stuck at the planning phase.
Here are a few of the considerations we evaluated as we updated our crop rotation plan as well as how we are currently factoring some of these into our eight-year crop rotation for Zone 5b:
Alternating crops needing compost
Companion (and combative) plants
Bed 1: Roots #1 -- intercrop dwarf white clover (early July); row cover; broadfork
Bed 2: Greens + compost -- intercrop oats (end of August/early September); spring row cover
Bed 3: Roots #2 -- intercrop dwarf white clover (early July)
Bed 4: Squash + compost -- intercrop sweet clover (early July); tarp in spring; hoop tunnel
Bed 5: Brassicaceae -- intercrop herbs (cilantro, rosemary, nasturtiums, borage, and chamomile) + sweet clover (early July)
Bed 6: Liliaceae + compost -- intercrop buckwheat (after scapes)
Bed 7: Solanaceae -- intercrop lettuce + basil; broadfork
Bed 8: Legumes + brassicas + compost; tarp in spring; hoop tunnel -- intercrop clover (brassicas) and vetch (beans)
Asparagus Bed: intercrop parsley and basil
As shown above, when I was updating our new crop rotation I physically drew it out for the 2021 season to better understand how I could incorporate these other considerations. While a little time consuming, it helped to visually see things like the spacing between different plants, the location of crops that needed compost or early season row covers, the planting dates and areas that we could add succession planting, etc.
It took three revisions but I have an updated plan I feel good about! Going through these additional steps was useful in other ways as well. I created a planting calendar that provides and month-by-month guide to when I need to start seeds indoors, transplant or direct plant seeds outdoors, add compost or other soil amendments, etc. Starting with healthy seedlings is another important factor in reducing pest and disease pressures on our crops. So having a plan for when things need to happen can only help ease my workload as well as minimize problems right out of the seed packet.
Happy garden planning!