Right now, it seems like vegetable garden season will go on forever. But we know eventually, the cold weather will show up and put an end to our garden. Since we know it’s going to happen, let’s talk about a couple of things that often get overlooked that could help us out next year, crop rotation and cover crops.

If you are like me, you have your favorite garden layout. The tomatoes go here, and the cucumbers go over there, and green beans back there, and then the peppers are right here etc. There’s nothing wrong with having a favorite way to layout your garden, but the reality is that if you plant the same crops in the same spot year after year, you are just asking for trouble with plant disease.

Each year we plant a tomato in that particular spot, is a year where the disease gets a little further entrenched in that location. You do this long enough and eventually you can’t plant tomatoes there ever again. Granted, ever again may be a slight exaggeration, but it will be a while before it is safe to plant there again. To avoid this, we rotate our crops. The general recommendation is to rotate your crops at least every three years, but many gardeners rotate on a yearly basis.

On the surface, plant rotation seems pretty simple. You just plant your crops in a different spot each year. But here’s the rub. Let’s say you have a place where you tend to plant your tomatoes. When you rotate, you move your tomatoes and plant bell peppers there now. Then in a couple of years you rotate again and plant eggplant in that spot. Well guess what? These plants are all in the same family, so your rotation efforts haven’t accomplished what you set out to do.

You see, tomatoes, eggplants, bell peppers, and potatoes are all in Solanacea or Nightshade family. As such they share the same diseases. So. In spite of your best efforts, you have been contributing to a possible buildup of disease in that area.

To rotate crops effectively, you are going to need to spend a little time getting familiar with the plant families and rotate by plant family rather that just a different plant.

Here’s a quick overview of the vegetable plant families.

Solanaceae or Nightshade Family - tomato, eggplant, bell pepper, and potato

Leguminosae or Bean Family - peas, green/string beans, fava beans, cowpeas, peanut

Curcurbit or Gourd Family - cucumber, melons, watermelon, winter squash, zucchini, gourds, luffa

Malvacea or Mallow Family - okra, cotton, hibiscus

Alliaceae or Onion Family - onion, garlic, leek, chive

Poaceae or Grain Family - corn, rice, wheat, lemon grass, sugar cane

Asteraceae or Aster Family - lettuce, artichoke, sunflower

Brassicaceae or Mustard family - broccoli, cabbage, cauliflower, kale, mustard, radish

Chenopodiaceae or Goosefoot Family - beet, chard, spinach

Apiaceae or Parsley Family - carrot, parsley, coriander, fennel, celery

Did you see some surprises in there. It’s usually a surprise for people to find out that tomatoes and potatoes are in the same plant family since the crops we eat from those plants are so different, but they are. So, when planning which crops you are going to rotate and where you are going to place them, be sure to take the plant family into consideration.

I mentioned in a recent article that we had a problem with watermelon mosaic virus in our squash plants at the farm this year. To counter that we’re going to be acquiring seeds that have some disease resistance built in for next year. But we’ll need to also do this for our cucumbers, cantaloupes, and watermelons since they are all in the same family. Ok, enough about plant rotation and plant families.

Next, let’s talk about growing a cover crop this winter to help add both nutrients and organic matter back into your soil. Sometimes cover crops are called “green manures” since they add nutrients back into the soil like manure does.

Some good options for cover crops would include clover, beans, peas, annual ryegrass, oats, winter wheat, winter rye, or buckwheat. To find these seeds you may need to go to a farm supply store or shop online. Here’s how they work.

Once you have cleared all of your vegetable crops out of your garden space, you plant your chosen cover crop. Of course it will likely need to be watered during the winter, but for the most part, you just leave it alone. Then in the spring, you till the crop into the soil so you are ready to plant your spring and summer crops.

Essentially, cover crops such as peas, beans, and clover pull nitrogen from the air and convert it into a form the plants can use, storing this nitrogen in its roots. In the spring when you till these crops into the soil, you are releasing that stored nitrogen into the soil along with some good organic matter. Now, this won’t supply all your plant’s nutrient needs, but it will help. Plus, it will help keep your soil in place over the winter like a good mulch.

If you would like to read more about plant families and cover crops, we have some good information on our website. Just go to www.tulsamastergardeners.org, click on the Lawn and Garden Help tab, and then select Vegetables. You’ll find the info there. See you in the garden!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: Wendy VanDyk Evans, Bugwood.org