If you’re a vegetable gardener, you have probably been in your garden planting or tending to the young plants that have already found a home there. I have talked to a few gardeners who don’t understand why the tomato plants they put in three years ago produced beautifully, while the ones they are planting now, in the exact same spot, just don’t seem to have the same oomph.

The problem lies in the soil, or more accurately, what is lacking in the soil. Growing the same plant in the same location year after year depletes the soil of the nutrients the plant requires to produce at its full potential. Plants belonging to the same family also share the same pest and disease problems.

Crop rotation not only moves plants out of soil that may have built up soil-borne diseases that affect their growth and productivity, but it also puts a kink in the meal plan of insects that have overwintered in the soil.

Think of crop rotation like a three-year vacation rotation. The Brassicas visited plot one this year, so next year they will vacation in plot number two, and the year after, plot number three. Although rotating crops yearly can help maintain good soil health, a three-year plan, or more, is ideal. Here are the families and their members:

• Alliaceae (onion family) – Onion, garlic, leek, shallot and chive;

• Apiaceae (carrot family) – Carrot, parsnip, parsley, celery, dill, fennel, lovage and parsnip;

• Asteraceae (sunflower family) – Lettuce, endive, salsify, Jerusalem artichoke and tarragon;

• Brassicaceae (mustard family) – Cabbage, broccoli, cauliflower, Brussels sprouts, kohlrabi, turnip, Chinese cabbage, kale, collards, mustard greens, radish and rutabaga;

• Chenopodiaceae (goosefoot family) – Beet, Swiss chard and spinach;

• Convolvulaceae (bindweed family) – Sweet potato;

• Cucurbitaceae (gourd family) – Cucumber, muskmelon, watermelon, summer squash, winter squash, pumpkin, gourd and honeydew melon;

• Fabaceae (pea family) – English pea, snap bean, lima bean, soybean, cowpea and field pea;

• Malvaceae (mallow family) – Okra and cotton;

• Poaceae (grass family) – Sweet corn, popcorn and ornamental corn; and

• Solanaceae (nightshade family) – Tomato, pepper, eggplant, Irish potato and husk tomato.

Depending on the size and number of garden beds you have, some planning will be necessary. When dealing with a large number of beds and vegetable varieties, keeping track of who lived where and when could be difficult. A garden journal with this information will help keep you on track.

If only planting one season, and once within that season, it is as simple as naming the beds and what was planted there. If planting multiple times within the season, or for year-round planted beds, extra details, such as dates and locations within the beds, are crucial to successful crop rotation.

Single-bed vegetable gardens cannot effectively be rotated, however, some of the nutrients can be replaced by planting light feeders after heavy feeders or with the use of cover crops. A soil test will tell you which nutrients are lacking, the pH levels and how to amend the soil.

Crop rotation will not provide plants will all the nutrients they require. Heavy feeders, such as tomatoes, broccoli, eggplant, beets, lettuce, and other leafy crops, benefit from the addition of good aged compost at planting as well as regular fertilization throughout the growing season to replace nutrients in the soil.

Herbs make wonderful companion plants and further the effort to thwart menacing pests from reaping the benefits of your plantings before you do. Rosemary discourages beetles from beans, chives and garlic deter aphids, and thyme keeps away cabbage worms. Most pests steer clear of oregano. Marigolds, many of which are edible, fend off hornworms and many other insects all while adding a little color to the veggie garden.

Keep those veggies moving!

Until next week, happy gardening.

— Irland, a member of the Limestone County Master Gardeners, can be reached at kippirland@hotmail.com. Visit http://mg.aces.edu/limestone for more information on the Limestone County Master Gardeners.