Garden crop rotation has been practiced by gardeners and farmers for centuries and is a vitally important strategy for ensuring crop success.
Unfortunately, while it’s even more critical for small farms and gardens where space is at a premium, rotation systems often aren’t utilized because they’re considered too difficult to follow.
But it doesn’t have to be that way; there is a simple method for rotating crops.
- What Is Garden Crop Rotation
- Why Rotate Garden Crops
- How Crop Rotation Improves Gardens
- What Happens If You Don’t Rotate Crops
- Simple Garden Crop Rotation Plan
- Leaf Group Plants (Need Nitrogen)
- Fruit Group Plants (Need Phosphorus)
- Root Group Plants (Need Potassium)
- Legume Group Plants (Produce Nitrogen)
- Implementing The System
- Space Saving Strategies
- Adding Amendments
- Garden Crop Rotation Results
What Is Garden Crop Rotation
Crop rotation is the practice of dividing the garden into sections and planting a different plant group in each section every year. But, the systems for planning crop rotations can be complex and hard to remember.
For example, in The New Organic Grower, Eliot Coleman describes both eight and ten-year rotations. These are terrific for larger gardens but seem overly complicated for my small garden plot.
So instead, I’ve been using a simple rotation system, and prefer it because it’s easy for me to remember. I’d quit when I tried to use complex systems because I couldn’t easily figure out where things should be planted. At least, not without consulting a book or a long list of rules. And that was a shame because the benefits of rotating crops are so numerous.
Why Rotate Garden Crops
Crop rotation reduces insect pests, diseases, and weeds while also improving soil fertility and the availability of nutrients to plants. It allows gardeners to keep beds in continuous production and minimizes the need for artificial fertilizers and amendments.
Who doesn’t want fewer insects, diseases, and weeds along with lusher gardens and plants? Especially when trying to maximize production in smaller spaces.
How Crop Rotation Improves Gardens
Pests and diseases are minimized because when the insects and diseases that affected the plants grown in a particular plot the previous year wake up in spring; those plants have been replaced with new crops that are not bothered by the same pests or diseases.
For example, when the tomato-loving bugs and diseases wake up in last year’s tomato bed, those tomatoes aren’t there. Instead, perhaps they’ll find onions, and die trying to find their way back to those tasty tomatoes.
In plots that are repeatedly used to grow the same plants, disease organisms and pests build up over time. This results in eventual crop failure. Rotating crops controls the disease organisms and pests.
Rotating affects weeds similarly. The method used to weed a plant usually allows certain weeds to find favorable spots. But, by planting a different type of crop each year, those weeds can’t become established. Also, some crops (like winter squash and sweet potatoes) can “clean” a bed by simply smothering weeds.
This crop rotation method improves plant nutrition by making sure that plants with similar nutritional needs are grouped together; and then rotating them based on the availability of nutrients in the soil. This prevents nutrient depletion and allows you to target soil amendments in a systematic way for maximum benefit.
Soil fertility is also improved because different plants send roots to different depths. Deeper rooted plants open up the soil structure and make more nutrients available for shallow-rooted crops as they are rotated through.
What Happens If You Don’t Rotate Crops
Trials in the US, Canada, and Europe have all shown the same results. When the same plants are planted in the same beds from year to year; the production of everything from potatoes to snap beans to tomatoes declines dramatically. In many cases, yields decline by 50% when crops aren’t rotated, mostly due to soil-borne diseases and pests.
In my own garden, what was once hard, compacted clay has become loose, friable loam. Gnarly root crops are a thing of the past, as are a host of pests and diseases. The lush, thriving plants that now grow do not really resemble the plants that once struggled for life. Production has improved dramatically, all because of a simple rotation system.
Simple Garden Crop Rotation Plan
The system I use is a four-year rotation that puts plants into groups based on their main nutritional needs. The groups are leaf, fruit, root, and legume. The plants in the leaf group need lots of nitrogen, those in the fruit group need phosphorus, the root group relies on potassium, and the legume group puts nitrogen back into the soil.
By grouping everything into four groups, and then rotating them every year, a simple system is created that is easy to remember. Many soil-borne diseases (such as fusarium wilt and verticillium wilt) can persist in the soil for up to three years. So, a rotation of at least four years is helpful in controlling these and many other diseases.
In this system:
- The leaf plants follow the legumes, because legumes fix nitrogen, and the leaf plants need large amounts of nitrogen.
- The fruits follow the leaf plants because too much nitrogen prevents them from setting fruit (and the leaf plants have already used most of the nitrogen) but they need phosphorus.
- The root plants follow the fruits because they need nitrogen even less than the fruits, but need potassium.
- And finally, the legumes follow the roots to put nitrogen back into the soil, and the sequence starts over again.
Because this is a simple sequence, and it makes sense to me, I can remember how it goes each year. There’s a downloadable version of the graphic below here, if you’d like to keep it for your garden file.
Leaf Group Plants (Need Nitrogen)
The leaf group contains all the crops that need lots of nitrogen to grow big, tasty leaves and stems. This includes things like chard, lettuce, salad greens, herbs, spinach, and brassicas (cabbage, broccoli, cauliflower, etc.).
Nitrogen is the most water-soluble of the main nutrients and therefore the hardest to keep in the soil, so it’s important that the leaf group immediately follows the “nitrogen-fixing” legumes in the rotation.
Fruit Group Plants (Need Phosphorus)
The fruits group includes tomatoes, melons, cucumbers, peppers, eggplant, and squash. Fruiting plants are those that develop from flower pollination. They need phosphorus to set blossoms and grow fruit, but shouldn’t get too much nitrogen or they make all foliage.
Technically, corn is also a fruiting plant; however, it’s an exception that I grow with the leaf group because it needs lots of nitrogen. The fruit group tends to take up the most space, so growing corn with the leaf group helps to equalize the space needs of each group.
Root Group Plants (Need Potassium)
Beets, carrots, onions, turnips, radishes, garlic, and sweet potatoes are all root group plants. They need lots of potassium but little nitrogen. At this point in the rotation, there is little nitrogen left but the potassium that roots need remains.
Potatoes are a root crop too, but they are also members of the nightshade family like tomatoes, peppers, and eggplants. If I plant potatoes with the root group, this means that they follow the other nightshades in the rotation. And that means I inevitably find Colorado potato beetles infesting my potatoes. So, potatoes are another exception. I grow them with the legume group instead of the root group. This puts potatoes two years behind the rest of the nightshades and minimizes the potato beetle problem (also see Controlling Potato Beetles).
Legume Group Plants (Produce Nitrogen)
Beans, peas, peanuts, and legume cover crops add nitrogen to the soil by pulling it from the air and storing it in their roots. They are known as “nitrogen-fixing” plants because they have nodules along their roots, with specialized bacteria called “rhizobia”. These rhizobia allow them to absorb nitrogen from the air and then release it into the soil.
The legumes also appreciate open, airy soil for their nitrogen-fixing roots, so they follow the root group to benefit from the improved soil structure typically created by the roots. Also to ensure that there will be lots of nitrogen available for the leaf plants that will follow them in the next rotation.
Because of their “nitrogen-fixing” ability, it’s important to leave legume roots in the soil to decompose (don’t pull them out after they finish producing) so that the nitrogen for the next rotation cycle is available.
Implementing The System
To get started with this rotation system, it’s a good idea to have the entire garden area soil tested in the fall of the prior year. Then amend the soil with any recommended nutrients. By amending in fall, it gives the nutrients time to break down and become available by spring planting time.
Composted manure for nitrogen, bone meal or rock phosphate for phosphorus, greensand for potassium, and lime for adjusting soil PH are good sources for the main nutrient amendments that might be needed.
In spring, divide the garden area into four equally sized sections and plant each with one of the four groups. Ideally, all four sections should be big enough to grow everything for the largest group to be grown (the fruit group for me).
That way there is always enough room as the crops rotate through. Any extra space left open by smaller groups can be planted in cover crops to improve garden fertility. Also, by allocating enough space for the largest group, you’re less likely to sneak something into the wrong plot and spoil the rotation.
Space Saving Strategies
In urban settings, finding four plots large enough to hold all the plants in the largest group can be problematic, so it’s often necessary to get creative and incorporate vertical growing strategies, intercropping, and space-saving varieties.
For example, cucumbers and peas can be grown up vertical structures, corn can be planted directly into lettuce in late spring (intercropping), space-saving varieties of melons and squash can be used, and pole beans can be grown instead of bush varieties.
To further reduce space limitations during the growing season, crops can be succession planted, just make sure that each crop stays in the proper section of the rotation.
Each fall, I retest the plot growing the legume group and add amendments as indicated by the soil test results. This assures that all the nutrients will be available when the rotation starts again with the leaf group. I also add composted manure to all the beds every fall to improve soil structure and fertility.
The next spring, simply rotate the groups, moving the leaf group to where the legumes grew the previous year, the fruit group to where the leaf group grew, the root group to where the fruits were, and finally the legumes to where the roots were.
Garden Crop Rotation Results
That’s all there is to it, each year the crops continue in the same rotation. Garden production and soil fertility improve naturally, while weeds, diseases, and pests decline. There’s no need to memorize complex rotation patterns or follow cumbersome rules.
You’ll begin to notice that previously difficult crops become easy and enjoyable to grow because they’re no longer as bothered by pests or disease, while improved soil structure and nutrients support lush growth. That’s the beauty of crop rotation; it’s truly amazing what implementation of one simple system can achieve.
It actually makes planning the vegetable garden pretty simple. And if you need inspiration on what to plant – here’s a page with lots of links to Free Garden Seed Catalogs!