Tropical Gardening: A weed is often something of value

  • Courtesy of NORMAN BEZONA Most plants have value if 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 areas of raw lava land where it is a pioneer species. Unfortunately, it can be a hazard, when careless activities cause fires such as last week’s burn in the Waikokoa area.

A weed can be defined as any plant growing in the wrong place. Perhaps an even better definition, though, is 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 such as a pioneer species, trying to heal the wounds created by man or natural events such as 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 often are 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 such as Wainaku grass also is 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, though, 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 UHCTAHR 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 “rights” — 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 might 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- to 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 many of those seemingly pesky fellows are actually edible or medicinal?

Plants we often consider as weeds are usually types that appear wherever we disturbed the soil. They grow rapidly and often compete with more desirable species. They mature large quantities of seed, and they often are difficult to control.

Weeds often are described as undesired plants, plants growing out of place or plants considered to be nuisances. 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 traveled and dominated the land, these species benefited from his activities.

Because of their origin so close to the activities of man, many plants we call weeds were discovered to be edible or medicinal, and indeed can 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 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 can be boiled and used as a vegetable dish or used cooked in salads or stews. The leaves also can be dried and cooked later.

Many grasses are edible, especially the rapidly growing sprouts or shoots of larger growing types. Bamboo is an example.

The common Purslane, or Portulaca, has leaves and tender shoots that can be eaten raw. They often are 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 also can be eaten.

There are more than 100 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 automatically labeled them as being worthless. Better we call them a kinder more neutral term such as pioneer species.

That way, we can contemplate the concept that everything and perhaps everyone, no matter who, has value.

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