Ask the master gardeners

Q: What are the advantages of rotating crops in the vegetable garden and how frequently should it be done?

A: Crop rotation refers to the practice of growing dissimilar crops sequentially over time on a given plot of land. Growing the same crop in the same place year after year depletes the soil of nutrients, allows species-specific pathogens and insects to thrive and contributes to erosion.
Historically, failing to rotate crops is responsible for such agricultural disasters as the Irish Potato Famine and The Dust Bowl.

Because different families of plants have different nutrient needs and growth habits, and are targeted by different insects and pathogens, rotating sequentially through a variety of crops is less likely to deplete the soil or allow pests to take hold.

Commonly planted families include mustard (broccoli, cabbage, radish, Brussels sprouts, kale, turnip), squash (cucumber, melon, pumpkin), grain (wheat, oats, corn, rye), legume (bean, pea, clover), onion (onion, garlic, leek), nightshade (eggplant, pepper, potato, tomato) and carrot (carrot, parsley, dill, fennel).

When planning your rotation, try to balance plantings of heavy feeders one year with soil-improving crops the previous year. For instance, a crop of peas or beans could precede a crop of broccoli. Also keep in mind which plants are members of the same family.

For instance, because potatoes and tomatoes are members of the same family, they cannot be planted in succession. Most experts recommend allowing at least two, but preferably three or four years, between plantings of crops from the same family.
Kimberly Lindner, Bronxville, master gardener, Cornell Cooperative Extension of Westchester