Crop rotation involves sequentially planting different crop types in the same area across growing seasons. This practice is essential after growing potatoes because they are heavy feeders that rapidly deplete soil nutrients, especially nitrogen. Potatoes also leave the soil vulnerable to specific soil-borne diseases and pests, such as potato scab and the Colorado potato beetle. A thoughtful rotation plan aims to replenish the soil’s fertility and break the life cycle of these pathogens and insects.
Avoiding the Solanaceae Family
Potatoes belong to the nightshade family (Solanaceae), and planting any related crop immediately afterward is highly discouraged. Common garden vegetables in this family include tomatoes, peppers, eggplant, and tomatillos. These plants are susceptible to the same diseases and pests that affect potatoes, allowing issues like late blight and Verticillium wilt to build up in the soil.
Planting a non-host crop immediately following potatoes is the most effective way to interrupt the disease cycle. Pathogens like potato scab can remain in the soil and infect the roots of any subsequent Solanaceae crop. Rotating away from this family helps starve out these specific pests and diseases, which cannot survive without a host.
Prioritizing Nitrogen-Fixing Legumes
The most beneficial crops to plant after potatoes are nitrogen-fixing legumes, which directly address the soil depletion caused by the previous heavy feeders. Legumes like peas, beans, and clovers have a symbiotic relationship with rhizobia bacteria, which live in root nodules. These bacteria convert nitrogen gas from the air into a usable form for the plant, a process known as nitrogen fixation.
While legumes use some fixed nitrogen for growth, a substantial amount is deposited into the soil. When the plant dies or is cut back, the root nodules decompose, releasing stored nitrogen compounds for the next crop. Fast-growing legumes such as bush beans or field peas are excellent choices, as they can be planted quickly after an early potato harvest.
Other Suitable Crop Families
Beyond legumes, a successful crop rotation incorporates other plant families that diversify nutrient usage and root structures. Brassicas, including crops like cabbage, broccoli, kale, and radishes, are good options to follow potatoes. These plants draw different nutrients from the soil compared to potatoes, helping to prevent the depletion of specific micronutrients. Some brassicas, particularly mustard varieties, also produce biofumigant compounds that can naturally suppress certain soil-borne diseases.
Leafy greens such as lettuce and spinach are also suitable because they are considered light feeders with relatively shallow roots. Unlike potatoes, which require substantial potassium, these greens focus on leaf production and have lower overall nutrient demands. Planting these crops helps to rest the soil, and their different root systems promote soil structure improvement. Root crops like carrots and beets can also follow potatoes, as harvesting the tubers leaves the soil loose and friable, which is beneficial for straight growth.
Using Cover Crops for Soil Health
If the potato harvest occurs late in the season, planting a non-harvestable cover crop is an effective strategy to give the soil an extended rest. Cover crops are grown primarily to improve soil health and structure, rather than for consumption. Options like winter rye, oats, or buckwheat are often used as “catch crops” to prevent the leaching of unused nutrients, particularly nitrates, from the soil during the off-season.
These crops establish dense root systems that hold the soil in place, significantly reducing the risk of wind and water erosion. When the cover crop is later tilled into the soil or allowed to decompose, it adds substantial organic matter, enhancing the soil’s tilth and water retention capacity. Winter rye is noted for its ability to grow vigorously in the low temperatures of late fall, providing year-round soil protection.