Seasonal Crop Rotation

Rotating crops increases yield and improves soil health

This year, did you think to yourself that you’d had a bumper crop of a certain vegetable last year, but this year, not so much? It might have nothing to do with the greenness of your thumb. It might have much more to do with needing to rotate your crops. 

If you always grow the same crops in the same beds year after year, you might be noticing an increasing in pests and diseases, and a decrease in crop yield. It might be time to take a moment, think about rotating your crops, and then think about all the bounty your garden will give you in gratitude. Vegetable gardening is an ever-changing process—you must shift constantly from season to season, making adjustments with your garden according to temperatures and rainfall. 

As you’re rushing to get your seeds or seedlings planted each spring, you might not be thinking about where those crops were planted last year and perhaps even years before that. It could make all the difference. For example, if you move the tomatoes to where you had planted the zucchini and squash, it could confuse and confound the hornworms that like to dine on your tomatoes. 

Here are some tips for a successful crop rotation as you plan next spring’s garden. 

What does crop rotation mean?

It simply means you do not plant the same crops in the same location year after year. When you change the vegetables that grow in a certain spot, you avoid having certain pests and diseases that continually build up in the soil. Those pests and diseases live on the roots of the plant, so when you move them, those unwanted things have no place to live. It’s ideal to rotate a vegetable (or vegetable family) so it grows in a different spot every third or fourth year. 

And it’s not just about pests. Each plant requires different nutrients from the soil. A change allows the soil to breathe a bit and replenish. 

That means, if you had pests or diseases on your tomato plants this year, you’ll probably have them again, but even more so, next year. Move the tomatoes elsewhere and plant some carrots, broccoli, squash or lettuce where the tomatoes were. Keep to that for a few years, and then you can move the tomatoes back. 

Crop rotation is best when it stays “all in the family.”

You might not think tomatoes, peppers, eggplant, onions, and potatoes have anything in common, but they’re all nightshades. You would want to keep them together when you move them to a different location in your garden. 

There are many vegetable “families,” but most have only one or two members that we’d grow in our own home garden. And there are exceptions to crop rotations; perennial vegetables and herbs shouldn’t be moved yearly, mint spreads too quickly, and asparagus likes to settle in one spot for several years. 

Here are some other “family” groupings:

• Alliums: Onions, shallots, leeks, garlic
• Legumes: Green beans, almost all kinds of peas, peanuts, soybeans. They add nitrogen back into the soil.
• Brassicas: Broccoli, cauliflower, cabbage, brussels sprouts, kale, turnip greens, radishes, collards. They grow quickly, and they place a lot of demand on the nutrients in the soil. They also share pest issues, and they need nitrogen-rich soil, so it’s a good idea to plant them after the legumes, because they add exactly that nutrient back into the soil. 
• Umbellifers: Carrots, parsnips, fennel, parsley, dill. They don’t need much nitrogen, but they do need potassium in the soil for optimal growth. 
• Cucurbits: These are also known as “fruiting” crops. They include most varieties of squash, melons, and gourds. They place a heavy demand on the nutrients in the soil, so ensure it’s enriched and well fertilized. 
• Nightshades—as mentioned above. 

Diseases and insects

Vegetables in a certain family can all be susceptible to the same pests and diseases, so planting a variety of crops from many families is an effective way to mitigate that problem. Some pests and diseases prefer certain plants, and the longer those plants stay in the same place, the likelier it is they’ll take hold and destroy your crop. 

Soil-borne diseases and fungi can build up after years of growing the same plants in the same beds. Although rotating the crop might not solve all your problems, it can help. Carrots, cucumbers, melons, lettuce, potatoes, squash, and tomatoes are susceptible to soil-borne pests and diseases, with cukes, melons and squash getting many of the same ones. Keep that in mind as you create your rotation plan. 

Don’t forget that many weeds also harbor diseases that can impact your crops, so ensuring they’re as weed-free as possible will help reduce competition for nutrients and light, as well as benefit the overall health of the bed.  

As for those nasty bugs, moving the plants around can make it harder for them to survive the winter and that helps the next grouping of plants’ chances of being healthy and more productive. 

Rotating by family

There’s a formula you can follow to help you with your rotation. The focus is on your legumes first, because those are the nitrogen producers for the soil. 

• Brassicas should take the place of the legumes. Those leafy crops need nitrogen, and the legumes are known as “nitrogen fixers.”
• Cucurbits should take the place of the leafy brassicas. Their nitrogen needs are less, and too much can prevent them from producing much. 
• Umbellifers should take the place of the cucurbits. They need even less nitrogen than the brassicas. 
• Legumes follow the umbellifers. This is to start the cycle all over again. Legumes also benefit from coming after the root crops, because they like the looser soil and the root vegetables will have done that. 

Pro tips, in simple terms

• Brassicas are just really nitrogen hungry. 
• Onions like firmer soil that is left behind by the brassicas. 
• Legumes like that deep, well-dug soil that is left behind from vegetables like potatoes. 
• Corn, tomatoes and cabbage are “heavy feeders” so follow them with legumes to replenish the soil. 
• Umbellifers are lighter feeders and can follow any group if needed. 
• Feed your soil yearly with rich, organic matter and fertilizers formulated specifically for vegetables. 

A good rotation plan will improve the health of your vegetable garden for the long haul, so formulate a workable rotation plan, and maintain a garden diary to keep track of the process. It could make a real difference in the health and productivity of your garden.