Monday, July 26, 2010

Weeds Are Always Bad, or Are They?

Everyone hates weeds. We hear and read that the presence of weeds is harmful to the landscape. But, are there any weeds that have benefits to the landscape? Here’s what we’ve learned.

Oddly enough, there have been a few documented benefits to the existence of weeds in the landscape. Some weeds are considered to be native wild flowers. Naturally found in fields, they are admired and even protected for their beauty. In addition, flowers of certain weeds have been found to attract friendly insects that may prey upon undesirable pests. For instance, Queen Anne’s Lace, aside from being pretty, is known for hosting beneficial insect. Other weeds attract bees that aid in pollination.

Other positive attributes of weeds include soil retention and environmental indication. Many weeds protect topsoil from erosion due to wind and rain. Their roots, aside from holding soil, can penetrate often impermeable layers at extreme depths (20 feet sometimes) making drainage better. This action also aids in nutrient availability, since new resources can be reached later through the root decomposition.

We know that weeds can be an indicator of what’s going on around them. The amount of water, nutrients and minerals can often be analyzed through the existing weeds and their growth habits. Other factors can be examined such as pH levels, permeability and fertility of soil. Perennial weed communities (dandelion, blackberry, milkweed) are often the best indicators, as opposed to annual weeds or a single plant. Some weeds have a narrow tolerance for environmental conditions so factors can be easily noted. For instance, dandelions are a sign of alkaline soil, black medic is a sign of low nitrogen soil and clover is also a sign of low nitrogen soil.

Although weeds are usually thought of as a nuisance, their presence in the ecosystem may be beneficial to some extent. They are able to dictate what’s going on around them and often help in erosion, nutrient availability, and attraction of helpful insects. If handled appropriately, this indication process can be used by gardeners to analyze how their soil is behaving.

In our next blog, we’ll talk about best practices for eliminating weeds in the landscape!

Now that's a big weed.

Dandelion image courtesy of Univeristy of Arkansas, Division of Agriculture.
Milkweed images courtesy of Butler University, The Friesner Herbarium.

No comments:

Post a Comment