The Power of Weeds

Francha Barker, Master Gardener 

Let's get the definition of weeds out of the way first because to dwell on it sets the tone for undesired negativity. Commonly and simply, a weed is a plant growing where it is not wanted. Weeds have special qualities giving them such power. Understanding those qualities, we can harness their power.

Weeds don't just happen at random. Different conditions favor different plants. These particular plants, weeds if you will, might tell us something that we didn't know about our yards and gardens.

Weeds start showing up when a site has been disturbed from, mostly, human activity like gardening, construction, or fire. Wind and rain erode the ground. The ground gets walked on and compacted. Gravity moves soil down inclines. After a disturbance, bare land starts bleeding topsoil and nutrients, setting off a decline in soil health. In exposed soil, moisture doesn't retain or maybe enter. With less water, microorganisms struggle to survive. And on and on, the affected species survivals of plants, insects, and animals.

Nature has called weeds to rescue the soil. They jumpstart soil healing. Quick to establish, weeds rescue soil from the stresses of temperature extremes, bareness, poor moisture retention, water loss, microorganism depletion, and inadequate aeration. Weeds metaphorically stop the soil bleeding and resuscitate breathing. Bleeding must be stopped, and weeds are nature's primary defense system.

There are three basic life cycle weed strategies to have weeds in the ground ready to jumpstart soil healing: annual, biannual, and perennial. Annual weeds live only one growing season. They may produce huge numbers of seeds that may germinate the following season and grow into a new weed. Biennial weeds grow for two seasons after seed germination. The first season the plant forms a good root system and stores up food. The second season it produces seeds. Perennial weeds can live for many years. In addition to producing seeds, many perennial weed species can produce through an underground system of stems (rhizomes) that can grow up horizontally and send up new plants along the way.

Some weed species come to the rescue and hold the soil in place. For example, Taraxacum officinale (dandelion) is a perennial which grows from a large, thick taproot, deeply anchoring the plant and catching and holding water.

Some weed species come to the rescue and cover the ground, like a band aid to cover the bare soil and stop the bleeding of erosion. For example, Stellaria media L.(chickweed) is an annual which creates lush, green mats protecting the soil while it heals.

Some weed species come to the rescue and resuscitate soil breathing from hard, dry, compactness. For example, Rumex crispus L. (curly dock) is a perennial also with a large, thick taproot naturally aerating the soil. (And curly dock has the potential to produce 29,500 seeds per plant!)

It follows that which weeds are seen to show up can tell us the condition of the soil. Now we can truly harness the power of the weeds as soil health indicator plants. The aforementioned examples are indicators of conditions which might be a problem for our desired plant but make the weeds right at home. With that knowledge, we can change the conditions or choose a plant that is more suited to the conditions. University of California Agriculture and Natural Resources Master Gardeners are here to help.

Here's some more food for thought about the power of weeds:

Do you mulch with weeds?

Do you eat weeds?

Do you intentionally grow weeds to attract beneficial insects?