Stringing the words “wonderful” and “weeds” together in the same sentence will get you strange looks in agricultural circles. And frankly, we spend too much time and money around here trying to get rid of them. Still, weeds play a vital role in the health of the farm, springing up to cover bare soil, pulling nutrients up from far below ground.
The wonder of weeds is really that they set the stage for something else to come along and replace them; most of them only thrive where the soil has been disturbed, and different soils will spawn different kinds of weeds. In the greenhouses, where the soils have been intensively augmented with compost, the weeds are predominantly pigweed and lambsquarters, typical indicators of high fertility. Adjacent fields still sport plenty of buttonweed (that’s the one you see alongside all of the corn fields where the herbicides have just missed), but we are seeing more and more pigweed and lambsquarters as we loosen and enrich those soils. Looking at the differences in root structures can provide some insight into the unique suitability of each weed to its situation: buttonweed just goes straight down, looking for minerals that are absent in the topsoil; pigweed also has a substantial taproot, but puts more effort into sending roots throughout the top layer of soil, using what’s there.
We generally try to deal a deathblow to weeds before they get up to size, but we don’t panic if a few get ahead of us, as long as they do not negatively impact the crop. We figure that the weeds are just doing their job, and we can make good use of them by mowing and tilling them into the soil.
My favorite weeds are the perennials, like quackgrass and thistles. Although they are hard to control, I am continually amazed at their ability to survive and thrive through the worst we can throw at them. Both spread by sending roots under ground to a new location. Thistles go deep, typically ten to twelve inches, before spreading laterally. The roots are often spindly and weak; where they stop growing laterally and head for the surface, the shoots snap easily off from the main root where the plant stores its energy. (The trick to pulling thistles with your bare hands is to know that the thorns don’t grow in darkness—just move a little soil aside and grasp the roots.) Quackgrass spreads more shallowly, but I have seen the roots grow right through carrots and potatoes if left unchecked. On one occasion, I pulled up a single rhizome that was over six feet long! Now there’s a weed that knows how to move.

