Weeding for Value in the Garden

By Brenda Frick, Ph.D., P.Ag.

Weed scientists often define a weed as a plant growing where it isn’t wanted. Gardeners are more likely to consider a weed as anything they didn’t intentionally plant. But if our goal is to grow food of the highest nutritional quality, perhaps it is time to reconsider which plants we weed out. Several of our common weeds are much more nutritious than their pampered garden counterparts.

The following tables, summarized from a United States Department of Agriculture database, indicate that weeds can be an abundant source of minerals and vitamins. Lamb’s-quarter’s is high in protein for a leafy green plant, and is especially high in calcium, vitamins A and C and in some of the B vitamins. Pigweeds (called amaranth in the American study) are high in calcium and iron. These two nutrients can be especially important for women’s health. They are also high in potassium, which is considered important for managing stress. Dandelion is especially nutritious, being high in calcium, iron, B vitamins and vitamin A.

All values are for raw leaf, except broccoli which is for raw florets

All values are for raw leaf, except broccoli which is for raw florets.


The weeds listed here, much like lettuce, are more appealing when they are harvested young, before they begin to flower. Older leaves can be used as cooked vegetables. All can be extended for salad use by harvesting them young and waiting for the tender regrowth. With the annuals, nipping the tops off encourages new branching. Although purslane is relatively mild taste, most of these weeds have a somewhat stronger taste. Introducing them slowly, in salad mixtures, can reduce the surprise.

Of course, some people are quite sensitive to foods. These people should be aware of some cautions. Canada maintains an information system about poisonous plants that lists lamb’s-quarters, pigweed and dock as able to accumulate oxalates, and lamb’s-quarters and pigweeds as able to accumulate nitrates. These accumulations can make the plants toxic if eaten in large quantities. Lamb’s-quarters can also increase sensitivity to the sun, if eaten as a major portion of the diet.

The Canadian information system advises that many of the plants that it lists cause problems only when eaten in “prodigious quantities”. It is probably best, especially for sensitive individuals, to avoid “prodigious quantities” of any new food. A balanced and diverse diet is considered preferable for most people.

Plants are more likely to accumulate oxalates and nitrates where soil fertility levels are high or where herbicides such as 2,4-D have been used. People wild crafting these weeds should avoid areas that have been sprayed with such chemicals. Organically grown weeds may be less prone to these accumulations. People growing their own gardens will probably have little problem finding these weeds, and can manage their gardens to reduce potential toxicity.

The USDA database indicates that iceberg lettuce, one of the most commonly available salad greens, is of limited nutritional value. Mother Nature provides more nutritious alternatives. If we can broaden our perspectives and our palates, we can find vitamins and minerals in abundance and enjoy those weedy gardens. Perhaps we can even find a way to reduce competition in crop fields by marketing a second crop of nutritious salad greens.

Brenda Frick, Ph.D., P.Ag., is the Prairie Coordinator for the Organic Agriculture Centre of Canada (OACC) at the College of Agriculture, University of Saskatchewan. She welcomes your comments at 306-966-4975 or via email at brenda.frick@usask.ca . I thank Wanda Wolf for leading me to the USDA database.

References

U.S. Department of Agriculture, Agricultural Research Service. 2004. USDA National Nutrient Database for Standard Reference, Release 17. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp

Munro, D.B., 2003. Canadian Poisonous Plants Information System, http://www.cbif.gc.ca/pls/pp/poison?p_x=px

For weed recipes, see http://www.edibleweeds.com/
http://www.virtualitalia.com/recipes/edible_weeds.shtml

This article first appeared in The Western Producer, and is published here on the OACC website with permission.

Posted on the OACC website, August 2005