In fifth grade, I spent hours looking at a beautiful picture of a farm that was in my social studies textbook. Fifth grade was when I learned about things like crop rotation, strip cropping and contour plowing. Not being from a farm family, it was all new and interesting to me, but I didn’t think it would ever have a real-life application. Turns out I was wrong, at least regarding the part about crop rotation.
Crop rotation is important in the vegetable garden to help the soil maintain a healthy balance of nutrients and to prevent disease and pest problems. Studies show that yields from crops that aren’t rotated quickly fall as much as 40%!
There’s more to it, however, than just swapping around your tomatoes and beans each year.
Vegetables in the same family take the same nutrients from the soil and are subject to many of the same pests and diseases. Potatoes, tomatoes and eggplant are all in the same family and all are subject to some of the same fungal diseases. Placing a vegetable of another family into that spot the next year deprives the pathogens of the host plant they need to thrive.
Pest control works the same way. Say you have a bad infestation of some insect or another and they lay their eggs in the soil below the plants they are invading to overwinter. When they hatch in spring, it would be best (for the gardener) if they didn’t find a ready-made buffet of the plant they love growing overhead.
Some plants are more effective at extracting nutrients from soil than others. They draw nutrients from deep in the soil and when they die, their residues make the nutrients available to less proficient nutrient extracting plants that follow them in the rotation.
There are nine main plant families found in the vegetable garden that should be rotated. They are:
- Onion family: onion, garlic, leeks, shallots
- Carrot family: carrots, parsley, parsnips
- Sunflower family: sunflower, lettuce
- Cabbage family: cabbage, broccoli, kale, kohlrabi
- Spinach family: spinach, beets, chard
- Cucumber family: cucumbers, melons, squash, pumpkins
- Pea family: peas, beans
- Grass family: corn
- Tomato family: tomatoes, peppers, eggplant, potatoes
Many studies have determined the best way to rotate these families. Here are just a few: Potatoes follow corn, corn follows cabbage, cabbage follows peas, peas follow tomatoes, tomatoes follow beans, beans follow root crops, root crops follow squash, squash follows potatoes.
If you’d like to learn more about the science behind crop rotation, Eliot Coleman has an excellent chapter on it in his book The New Organic Grower.
Don’t get too caught up in this if you are a backyard gardener. Just keep it in the back of your mind and do the best you can. It would be a good idea to make a rough sketch now showing where you plan to place next year’s crops while the layout of this year’s garden is still fresh in your mind.
Leave a Reply