Good weeds. These two words together create what might seem to be the single biggest oxymoron in the gardening world. Weeds, good? How can that be? They compete with our crops for sunlight, water and nutrients; they invade our perennial beds; they creep into our lawns, our walkways and our groundcovers. Some of them are impossible to control, while others can cause hay fever and rashes or sting our flesh. What on Earth could be good about a weed? Lots. I swear. Let me explain.
By common definition, a weed is simply a plant out of place—something growing where we don’t want it. In our lawns and gardens, we usually consider anything we didn’t purposefully plant to be a weed, and we try to get rid of it.
Weeds, however, can serve a great purpose. Many of them provide habitat for birds and other wildlife, and they hold soil in place, preventing erosion. They cycle nutrients, supply nectar to pollinators, serve as a larval food source for certain species of butterflies, and harbor thousands of different types of beneficial insects known to naturally control lawn and garden pests. Uncultivated, un-mown areas of the landscape tend to host the greatest diversity of plants and beneficial insects. These ‘weedy’ places are valuable ecosystems. Even roadside ditches can provide critical habitat and host hundreds of different plants and animals. Allowing some weeds to grow on your property is a good thing, as it increases biodiversity and available habitat.
So how can you tell the difference between a good weed and a not-so-good one? Knowing which ones should be cultivated and which should be eradicated is not a cut and dry issue. Clearly, if a weed is affecting the health of a cherished plant or your vegetable garden or if it’s causing you to break out in hives, control is necessary. If it’s an invasive weed, one that “takes over the world,” it’s probably not in the ‘good weed’ category. But there are many plants that get placed on the bad weed list and don’t deserve such ranking. I’d like to introduce you to a few of my favorite ‘good weeds.’
1. White Dutch Clover
This sweet little plant was once found in every lawn. Prior to the invention of broad-leaf weed killers, a lawn filled with white Dutch clover was a thing of pride. Farmers cherished its ability to cycle nitrogen, break up clay soils and create delicious honey. Homeowners were thrilled at its ability to allow a lawn to stay green even in times of drought.
Grass and white Dutch clover are perfect partners. The clover produces nitrogen to feed the lawn (especially if you let the clippings lie after mowing), and its sturdy roots penetrate deep into the soil, allowing grass roots to grow deeper and access more water and nutrients, nearly eliminating the need for fertilizer and irrigation. It was only when weed killers came along that clover became a bad guy. With Honey bees suffering as they are, homeowners should go back to using a grass/clover mix. Clover is an ideal forage for Honey bees.
A terrific weed for low-lying, poorly drained sites, common milkweed (pictured above) produces a beautiful pink to light-purple flower followed by a seedpod filled with fluffy white seed umbrellas. The foliage serves as the only larval food source for the Monarch butterfly. In late summer you can find both the caterpillars feeding on the leaves and their utterly miraculous-looking chrysalises hanging beneath. The plant’s name comes from the thick, milky sap found in the stems and leaves. Other milkweeds, including swamp milkweed and butterfly weed, are also lovely additions to the garden.
There are dozens of different species of goldenrod that call North America home. It’s unfortunate that they get blamed for late-season hay fever attacks when in fact it’s impossible to be allergic to them. Their pollen is much too heavy to be borne on the wind. The culprit, instead, is often ragweed, which blooms at the same time. Its green flowers are much less obvious than the brilliant yellow blooms of goldenrod.
Goldenrods provide egg-laying and over-wintering habitat as well as nectar for many beneficial insects, including praying mantises, hoverflies, ladybugs, and lacewings. They can bring much needed late-season color to the landscape and are tolerant of even the poorest of soils.
I’ll start with a disclaimer on this one: I don’t mean Canadian thistles. Canadian thistles are invasive, aggressive and nearly impossible to eradicate. Instead, I mean those thistles that do not spread via underground stems. Field, swamp, pasture and bull thistles are the ones I put in the ‘good weed’ category and here’s why: Their seeds are favorites of several birds, including goldfinches, and their soft, tufted seed parachutes (known as thistle down) are used to line the nests of these beautiful little birds. Thistles can grow quite large, up to 6 feet tall depending on the 2 or 3 inches across and are favorites of nectar-seeking butterflies, bees and hummingbirds.
With succulent leaves, low-growing stems and puny yellow flowers, purslane certainly doesn’t look like anything special. It isn’t particularly attractive in appearance nor is it particularly attractive to any beneficial insect or bird. It is, however, really tasty. A non-native weed introduced from Europe, purslane tastes lemony and tart, and I think it makes a delicious addition to summer salads. It is used in many ethnic cuisines and is a highly nutritious green. Several cultivated species, bred to produce larger leaves and thicker stems, are available for vegetable-garden planting but I think the ones I find popping up in my garden all summer long suit just fine. I guess in this case, if you can’t beat ’em, eat ’em. (Before tasting any wild plant, be sure to have it properly identified by an expert.)