Friday, July 18, 2008

Is There Such a Thing as a Good Weed?

We all curse weeds in the garden, but what is a weed and can it ever be a good thing? I define a weed as anything that's growing where I don't want it. The offspring of one season's prized tomatoes can be next spring's weeds! However, when we talk weeds, most of us mean common invaders like bindweed (Convolvulus arvensis), chickweed (Stellaria media), and other plants we fight every garden season.

What good could come of a common weed? Some weeds with taproots like dandelion (Taraxacum officinale) break up compacted soil. The deep rhizomes of horsetail (Equisetum telmateia) help bring nutrients up from deep in the soil. A winter cover crop is nice, but even weeds are better than bare soil. They help prevent erosion and trap nutrients that would otherwise leach from the soil.

Most over-wintering weeds begin blooming sooner than other plants, providing an early food source for foraging insects like honey bees (Apis mellifera). Any leafy plants left growing in the garden provide a home for beneficial insects like ladybugs (Coccinella sp.) and spider-like daddy longlegs (Leiobunum sp.) On the other hand, I invariably find cutworms (larvae of most moths in the Noctuidae family) hiding among the weeds in my plot. Larger weeds like the Himalayan blackberry (Rubus procerus) provide cover and food for birds and other small animals.

When chatting about weeds, the question "What's the name of this weed?" always arises. Here are a few descriptions of the most common weeds in my garden. (Click on the linked scientific name to see photos to help you recognize these common weeds).

  • Bindweed (Convolvulus arvensis): That white morning glory's real identity!

  • Chickweed (Stellaria media): Light green mass of tiny leaves that slowly invades your plot over the winter and leaps to life in the spring.

  • Henbit (Lamium purpureum): Square stems look suspiciously like its invasive cousin, mint.

  • Poison hemlock (Conium maculatum): The feathery leaves of this biennial are deceivingly beautiful, but treat this dangerous plant with care. Wear gloves and a long sleeve shirt when pulling it. Bag it and throw it away with your household green waste.

  • Quackgrass (Elytrigia repens): This pesky grass grows from aggressive rhizomes. Each joint in the root can sprout a whole new infestation! Dig this weed and let it dry thoroughly or hot compost it before digging it back into your soil.

  • Shepherdspurse (Capsella bursa-pastoris): This starts out looking a bit like a small dandelion, but I think the small flat seeds look like hot pepper at the pizza restaurant.

  • Shotweed (Cardamine hirsute): These seeds shoot all over the place the moment you touch it.

With the exception of poison hemlock and quackgrass, you should simply pull your weeds before they go to seed and bury them 8 inches or deeper in your garden. That's too deep to re-sprout, and they will contribute to the organic content of your soil.

Copyright © 2006 Brian Ballard. All rights reserved.

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