I am betting that you’re already familiar with the idea of crop rotation. You may have seen large swaths of farm fields covered with corn one year and soybeans the next. That is crop rotation as its most basic level.
Corn is a nitrogen hog and soybeans are a nitrogen fixer. By planting them back-to-back, you help regulate the nitrogen levels in soil, while producing two important food staples.
More sophisticated monoculture rotations include corn, soybeans, wheat, a different nitrogen fixer (other legumes). Some even include using the fields to grow grasses and graze horses or cattle for several years before planting again. This practice of incorporating animal grazing is still fairly common in my region.
Though we often associate crop rotation with industrial farming, the idea of rotating fields is an ancient practice. The early rendition is often referred to as “food, feed, fallow” and has been traced back to ancient Rome.
Essentially, in the first year farmers would grow crops for humans. The second year they would grow grains and graze animals. The third year, they’d let the field rest so the manure age. Then the cycle would start again.
Farmers – and more recently gardeners — have been experimenting with crop rotations to varying degrees since those ancient times. In this three part blog series, I am going to go over some of the main reasons why crop rotation is important and how you can do your crop experimentation at home.
Making your own crop rotation plan based on what you are growing and how you are growing it will get you much better results than following pre-fab rotational plans made by others who may not have the same challenges as you. That’s because we all have different pest pressure, different pathogen risks, and different ways of amending and tending our gardens.
So, let’s dig into the details of how to create your own crop rotation plan at home.
Why Use Crop Rotation?
There are three primary reasons why people use crop rotation. These include pest prevention, pathogen control, and nutrient management. Let’s get started by examining pest control.
Pest Control – Rotate Your Planting Times
One of the most common reasons to rotate crops is for pest control. If you were growing a large field of pesticide-free cabbage in the same location, year after year, I bet you’ll end up with a severe cabbage moth problem.
A single cabbage moth can lay 2500 eggs in a season. Even if you are diligent at picking off eggs, let’s say you miss some and ten female cabbage moths make it to maturity and begin to reproduce. Each of them also lays 2500 eggs and has 10 females (and a few males) make it to reproduction. This goes on for a few seasons.
Even with just a minuscule number of survivors, from 1 moth, you jump to 10 moths, from 10 moths to 100, from 100 moths to 1000 in just four seasons. Instead of picking off 2500 eggs, you now have to pick off 2,500,000 eggs! In a field full of cabbage, finding all those eggs is impossible and so the problem grows.
Luckily, it’s easy to break this cycle. Since cabbage moth larva feed pretty exclusively on brassicas or cole crops, take away their food supply and the cabbage moths will have no place to lay their eggs. Without suitable host plants for their eggs, the moths will fly off and look for a better place to lay. Viola, pest problem solved!
Why Field Crop Rotation Practices Will not Help the Home Gardener
For the home garden, though, crop rotation for pest management has to be a bit more strategic than just changing planting locations from year to year. Here’s why.
Let’s say you have a 20 x 20 foot garden. Even if you plant cabbage at the top of your garden one year, and the bottom of your garden the next, cabbage moths still only have to fly 20-40 feet to lay their eggs on a host plant. My garden is 100 x 60 feet and cabbage moths fly over the entire area and then go visit my flower patches an acre away. Trust me, 20-40 feet of difference in planting location isn’t going discourage cabbage moths.
How to Use Crop Rotation Strategies for Pest Control in a Small Garden
For crop rotation to be effective in a small garden, you need to think beyond rotating rows and instead think about rotating the timing of your planting to break up the reproductive cycles and prevent infestations.
To do this, you need to know the life cycle for the pest you are trying to control.
As an example, the cabbage moth typically has two generations of offspring each year. The first starts in mid-spring and the second in late summer. If you are planting cabbage in both spring and fall, you are literally offering cabbage moths the perfect conditions to increase their numbers from year to year.
Strategy 1: Shift your Planting Season
A good rotation strategy for controlling cabbage moths and still getting an annual cabbage crop would be to plant in spring one year and fall the next year. By doing this, you cut off the larva food supply during two reproductive cycles back-to-back. Cabbage moths either get the clue and move on or they fail to reproduce successfully. Either way, you win!
Strategy 2: Start Early or Late using Larger Transplants
If you must plant cabbage in both spring and fall, then starting earlier or later can help. Mature plants can withstand more insect damage than smaller plants. By transplanting larger plants into prepared soil before the cabbage moths begin laying, you can increase your yeilds by giving plants a head start over moths.
The challenge with this strategy is that cabbage doesn’t always transplant well after it gets bigger. Growth may be stunted plants may suffer shock.
Using paper pots that will quickly decompose in the soil can help limit root damage.
Growing transplants in extremely loose planting medium can also make it easier to relocate plants without causing root damage. Note, loose soil medium often requires more watering and nutrient management than heavier mixes.
Strategy 3: Use Observation and Experience to Create Pest Prevention Rotations That Work
Here’s another example to help you figure out how to use the idea of crop rotation for pest control in your garden.
Our first year here, we planted potatoes in an area that had once been covered with crabgrass. We tilled up the soil, amended with compost, and started planting.
Unfortunately, I barely got any potatoes because we ended up with an infestation of wire worms. Those orange mealy-worm-looking guys love living in the roots of grass. It’s like the wire worm equivalent of a nice little house in the suburbs.
Well, when I swapped their suburban grass roots for potatoes, it was like I took those root eaters to Vegas and told them to have a great time on my tab. They went crazy, decimated my potatoes, and exploded their population in the process. Wire worms gone wild in my potato patch…Yikes!
That experience taught me something though. Don’t plant potatoes after grasses if you have wire worms! Since corn, sorghum, and wheat are grasses, I don’t plant potatoes after those plants for at least two years as a habit now.
Strategy 4: Keep Adapting Your Rotation Plan for New Pests
Good crop rotation for pest management is not just a “set and forget it” kind of activity. It’s something you’ll need to update as new pests make their way into your landscape.
Last year I saw my first blister beetle. Actually, I saw hundreds of them. They were demolishing the leaves of my potato plants. This brand new pest had sailed in and started devouring plants that I’d been growing diligently for over three months.
Well, I wasn’t going to have that! So, I got a bowl of water and started knocking them into it.
My chickens love eating all sorts of beetles. I was about to take those pesky pests to my chickens, when some inkling of intuition told me to identify them first. I covered the bowl and hit the computer.
First site I found started with something like “lethal to livestock”. They call them “blister beetles” because they cause blisters if you squish them by hand. The same substance that causes blisters in humans can kill a chicken with the smallest taste and even take out cattle with large infestations.
More research revealed that pigweed is a host plant for these bugs. I wasn’t growing pigweed, but I was growing Elephant Nose amaranth – pigweed’s city cousin – right next to my potatoes.
I went back to the garden, checked my amaranth plants and discovered even more blister beetles. They were covered with them. Except the blister beetles weren’t eating the amaranth – they were just living there and going across to the neighbors for dinner (e.g. my potatoes). I had found their secret hideout!
Well, down came the amaranth, and out went the blister beetles. I had to pick some more off my potato plants since they apparently hadn’t gotten the memo that I’d destroyed their habitat. However, they didn’t return once I removed the amaranth from my garden.
I had been using amaranth as an exotic edible to sell at the farmers market and as a trap plant for flea beetles since they like it a lot more than my other leafy greens. However, those blister beetles are such bad news that amaranth is now rotated out (of the garden) for good.
Steps For Making Your Own Pest Prevention Crop Rotational Schedule
As you can see, using crop rotation for pest control in a small garden is not just about moving plants to new locations. It is about managing pests by knowing their reproductive cycles, their food and habitat preferences, and using that understanding to plan useful rotations.
I Know it can be a bit tricky to figure it out at first. Try these tips to help plan your strategy.
- Start by identifying your most persistent pests.
- Study up on how the multiply, what they eat, and where they live.
- Use that knowledge to time your planting to interrupt reproductive cycles, limit the pests’ food supplies, and offer less hospitable habitat. Aim to break up at least one reproductive cycle to keep your populations in check. You may need longer interruptions for serious infestations.
- If your strategies effectively reduce pest populations, then incorporate them into your planting calendar and crop rotation plan.
- Repeat as necessary!
Other Examples of Pest Prevention Crop Rotations
Here are a couple other rotations I have figured out based on our pest pressure that might help you create your own rotations.
1. Squash Bugs
Squash bugs only have one reproductive cycle per year. However they are so good at hiding and flying large distances that it has proven impossible to control them with short interruptions.
Instead, we only grow plants in the curcurbit family for two years, then we take a year off.
We still hand-pick and kill squash beetles. We also choose varieties like Seminole Pumpkin and a Virginia strain of Waltham Butternut Sqaush that seem less bothered by these pests than other squashes.
During our off year, I arrange to have others grow us squash and cucumbers in exchange for something we are growing. Or I buy from local farmers I trust.
After our yar break, we still have a few squash beetles that have managed to stick around or found us again. However, their numbers are low and controlling them is easier! This strategy seems to prevent squash borers too.
2. Mexican Bean Beetle
I thought I’d struck gold when I first saw these yellow lady bug looking insects moving in to my garden. Who wouldn’t want thousands of beneficial lady beetles to come eat your aphids and other pests?
Except, these lady beetles were the one kind that is not beneficial to your garden. These were Mexican Bean Beetles. Within days they had consumed by bean leaves and desiccated my vines.
I tried to pick them off. Since I had planted the three sisters (beans, squash, and corn), I couldn’t find them all and their population exploded (as described for cabbage moths above).
Well, then I noticed that they had left a few plants mostly unscathed. Those were the plants running along my fence, planted on their own, mostly for aesthetic purpose, that I’d been watering regularly because they were closer to my water barrel.
The next year I planted a bunch of beans in a plot by themselves. I neglected them – no watering, no weeding. Those sad little plants still managed to grow and even produce, but they were clearly quite stressed.
When the bean beetles emerged, they went straight for my sad little bean patch. I waited until they had laid their eggs and saw a few larva crawling on the plants. Then I yanked those plants and burned them!
After that I planted my real beans in a different location. I treated my new plants like royalty to ensure good health. I still had a few bean beetles show up on my well-cared for real beans. Since I planted those beans on flat trellises rather than as a companion planting, I picked survivors off with ease.
This strategy worked well because bean beetles do most of their laying in June in my area. This still left me plenty of time to plant and grow beans late in the season.
Since I am planting beans later when our temperatures are warmer, I choose varieties that germinate in warmer temperatures and can take the heat. Cowpeas always germinate in high heat, but there are other varieties that work well like scarlet runner beans.
Final Words on Crop Rotation for Pest Control
This might seem like a lot of information to take in. But I have literally just shared my entire crop rotation plan for controlling pests in my garden.
- I use seasonal cabbage rotations to control cabbage moths.
- I rotated amaranth out of the vegetable garden permanently.
- I take a year off after two years of growing curcurbits.
- I grow a trap plant for Mexican Bean beetles and plant my my real bean crop after the mating season for this troublesome pest has passed.
I have a few more pests that visit my garden like Harlequin bugs, aphids, and tomato hornworms. Luckily, their populations are so small, that hand picking is sufficient to keep them in check.
You won’t need to use crop rotation practices for every pest you have, just those that interfere with your production (or that might be dangerous to livestock, like blister beetles). However, there are two other big reasons why good crop rotation is important. And we’ll get to those – pathogen control and nutrition management – in our next two posts.
What kind of insect pests are you dealing with in your garden? Do you use crop rotation to help manage them already? What works? Or has this post sparked some new ideas you might try this year? Please share your challenges, ideas, and successes using the comment area below. I’d love to hear your thoughts!
The post Crop Rotation for the Home Garden, Part 1: Pest Control and Pathogen Prevention appeared first on The Grow Network.