A weed is often something of value

  • Most plants have value of we open our minds. Visiting Medellin, Colombia, we often saw fountain grass used as a landscape plant. In drier regions of Hawaii, it covers vast area of raw lava land where it is a pioneer species, Unfortunately, it can be a hazard where careless activities can cause fires like last week's burn in the Waikoloa area. (Voltaire Moise/Courtesy Photo)

A weed may be defined as any plant growing in the wrong place. Perhaps an even better definition for a weed is a plant for which we haven’t found value.

Just like there is no such thing as a bad child only bad behavior, there is no such thing as a bad plant. It is just that we haven’t yet figured out its use. Perhaps a better word to describe what we call weeds would be a less negative term like calling it a pioneer species trying to heal the wounds created by man or natural events like lava flows and hurricanes.


A banyan tree in the park is great, but when one sprouts up on your roof, it’s a pioneer species. What we call weeds in lawns are usually the result of poor management. Lawns injured by insects, fungus, or nematodes will readily become infested with pioneer species. Improper mowing, watering, and fertilization will lead to a lawn chock full of species we didn’t want. So, don’t blame what we call weeds for a poor lawn. They are often just a symptom of improper maintenance practices. Besides, dandelion leaves make a great addition to salads or cooked as greens.

When it comes to turf, high quality, weed free cuttings or seed, properly established, is important. Soil that is not infested with perennial tough guys like wainaku grass is also a basis for preventing a lawn with undesirable outcomes. After that, proper management practices that result in a dense, vigorous turf will aid in preventing guests. Once they get established in lawns, it is difficult to get control. If you ultimately decide you must use an herbicide, then here are some things to consider.

Product availability is changing so fast with the pesticide concerns that it is difficult to make general recommendations. Check with your local garden shop or call the UH-CTAHR Master Gardener Helpline in Kona or Hilo for specific problems.

Just like the three “R’s” of learning, we find some very important “R’s” related to the application of herbicides. These “R’s” are to the right material, at the right time, in the right amount, applied in the right way. Understanding all the instructions of an herbicide label to be sure it will control your specific problem without injuring your plants is as vital as using the right amounts. Safety margins may be smaller than you think. To apply pesticides in the right way, you must choose equipment that will give proper coverage. Spray jars that attach to your garden hose are good where you need to apply nutritional sprays, fungicides or insecticides to the lawn. However, with herbicides, it’s a better idea to use a small 2-3 gallon tank sprayer. A tank sprayer is vital since hose attachments are not accurate enough.

If you end up having to remove unwanted species by hand, smile. Let’s take a positive approach to them. Did you know that many of those seemingly pesky fellows are actually edible or medicinal?

Plants we often consider as weeds are usually types that appear wherever we have disturbed the soil. They grow rapidly and often compete with more desirable species. They mature large quantities of seed, and they are often difficult to control. Weeds are often described as undesired plants, plants growing out of place, or plants that are considered a nuisance. Both the characteristics and the definitions of weed emphasize that they are plants closely related to man. They come and go as man disturbs the soil. Just as man has traveled and dominated the land, so have these species benefited from his activities.

Because of their origin so close to the activities of man, many plants we call weeds have been discovered to be edible or medicinal, and indeed may be used as beneficial herbs throughout the world.

So when you go out to pull what we call weeds, it’s easier if you know they could be for dinner or to help heal a cut or settle an upset stomach.

For example, one of our most common weeds is the Spanish needle (Bidens pilosa). The young shoots may be boiled and used as a vegetable dish, used cooked in salads or stews. The leaves may also be dried and cooked later. Many grasses are edible, especially the rapidly growing sprout or shoot of larger growing types. Bamboo is an example.

The common purslane or portulaca has leaves and tender shoots that can be eaten raw. They are often used in salads or cooked as a spinach dish.

The familiar cattails of swampy areas are a source of several kinds of food. The starchy tubers are edible as young flower spikes. Young leaves are also eaten.


There are more than a hundred edible plants referred to as weeds. If you are interested in these and other useful plants, check at the local library or do a computer search for “Edible Leaves of the Tropics” by Franklin Martin and Ruth M. Ruberte—Mayaguez Institute of Tropical Agriculture, P.O. Box 70, Mayaguez, Puerto Rico, 00708.

And don’t forget, when we refer to plants as weeds, we have automatically labeled them as being worthless. Better we call them a kinder more neutral term like “pioneer species!” That way we can contemplate the concept that everything and perhaps everyone no matter who has value.