Rotating vegetable families through the garden reduces pest damage

Posted April 01, 2011, at 10:18 p.m.

What do vegetable farmers do in winter, in that time between harvest and the start of a new growing season?  I asked my Horticulture Technology students this question last week, an entry into discussion of vegetable plant families.

“They process the harvest,” offered by a student on last year’s field trip to a local farm where we threshed wheat, milled the berries and made wheat pancakes, all in the same afternoon. Good memory.

“They repair their machinery,” from another student. Good thinking.

“They plan for the next growing season,” came the answer I needed.

What does that mean, planning for the next growing season? This was my segue into the meat of the class, the need for crop rotation. Whether managing 100 acres of cropland or a handful of raised beds, every vegetable grower understands the need to rotate crops so that no vegetable type is growing in the same soil two years in a row.

So then we made a list on the blackboard of vegetables the students like to eat. Each veggie was added to one of six groups: tomatoes grouped with potatoes and peppers, peas with green beans, onions with chives, broccoli with cabbage and kohlrabi, cucumbers with melons and squash, and a really large group of root crops and leafy vegetables.

There were no labels above the groups; that came later. The board filled with the names of veggies, eggplants joining the tomatoes and potatoes, Brussels sprouts squeezed between kohlrabi and cabbage. Carrots grouped with lettuce and corn. What?

Some of the students thought they had a handle on what was happening, then corn ended up on the same list with lettuce. “Corn is related to carrots and lettuce?”

Over the confusing list of root crops and leafy veggies, I wrote the heading, “Other,” then “Nightshades” atop tomatoes and their kin. “Brassicas” tied the broccoli group together. “Cucurbits” labeled melons and such. And “Legumes” grouped peas with beans. Finally, “Alliums” wrapped up the onions and leeks.

I went on to explain that it is not enough to make sure that you avoid planting tomatoes in the same soil two years in a row. You don’t want to plant any member of the nightshade family where tomatoes were growing last year. Why?

Insect pests and plant diseases that plague tomatoes also are problems for the other nightshades (including tomatillos, a favorite in last year’s garden). All cucurbits suffer from the same pests and diseases, and so forth.

Crop rotation minimizes crop damage caused by insects and plant pathogens that overwinter in the soil.  It is a vital management strategy for the organic farmer (or gardener) who chooses not to use pesticides.

Vegetable crop growers also can put their knowledge of plant families to good use by growing members of the same family together, taking advantage of their similar management needs. While root crops and leafy vegetables (the “Others”) are not in themselves a botanical family, they do have similar growing needs, and thus are grouped together in the field or garden.

This is the planning that farmers and gardeners do during winter, mapping out the rotation of crops grouped by plant family. This is what we need to do in our schoolyard garden. It is what every gardener needs to do.

Heirloom Vegetables

Since my late-February column on heirloom vegetable varieties, those nonhybrid, non-genetically modified champions of flavor passed down from one generation of gardeners to the next, I have learned there are two garden centers in the area that grow transplants of heirloom tomato varieties.

Mary Hoskins of Greencare Plantscapes (1779 Hammond St., Hermon; 848-5453) wrote that she does grow out a limited number of several heirloom tomatoes, including Brandywine, Cherokee Purple (her favorite), Amish paste, Silver Fir Tree, Garden Peach, and Stupice. Mary said, “What exactly is the definition of ‘heirloom’ … ? Collecting tomato varieties is kind of like collecting hostas or orchids — you can really get carried away if you’re not careful.”

Also, Karen Ramsey, the grower at Ledgewood Gardens (563 Johnson Mill Road, Orrington; 825-4707) wrote, “For a good number of years our customers have enjoyed heirloom transplants from our greenhouses. We have Garden Peach, Cherokee Purple, Old German, Black Krim, Aunt Ruby’s German Green, Amish paste, Mortgage Lifter, Rose de Berne, Brandywine and Black Prince tomatoes.”

If you’re looking for locally grown heirloom tomato transplants, give these two garden centers a visit this spring. It really feels good to know there are local growers working to keep these old-time favorites around.

They are worth growing, just for their names.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to rmanley@shead.org. Include name, address and telephone number.

 

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