Editor’s note: This article has been updated.
Weeds are plants out of place. Each of these species have their own niche in their native ecosystem, but when introduced to disturbed soil around human habitation, can flourish out of control. They boldly claim space and nutrients intended for our chosen ornamentals or edibles. Some were deliberately imported, but spread far beyond the control of their propagators. Other weeds provided essential nutrients and healing remedies to our hunter/gatherer ancestors (modern foragers are rediscovering wild edibles — even the dreaded invasive Japanese Knotweed can make a tasty pie!).
Dangerous chemical weed-killers and costly landscaping services are marketed to concerned homeowners who are confused about how to make their lawn resemble an idyllic manicured golf course. Fortunately there are alternatives. Your weeds are trying to tell you something. Once you learn a little of their language, these misunderstood plants can often provide the information you need to adjust your soil health and cultivation techniques naturally.
When assessing your lawn or garden area, just scan for the dominant weeds and overlook the occasional volunteer. If you don’t know their names, find out. There are several basic problem areas to look for: pH imbalance (too acidic or too alkaline), fertility imbalance (too rich or too poor), soil compaction or crusting, and moisture imbalance (too wet or too dry). Here are several common weeds and a rough translation of their message to you.
Crabgrass
An opportunist, crabgrass often shows up in newly planted lawns where fertility is high and space is available. Both drought and sogginess can give crabgrass an advantage over lawn turf, since the plant thrives in challenging conditions. Water lawns deeply to a depth of 4-6 inches. Avoid frequent, shallow watering.
In addition, make sure you’re not mowing your grass too low: you can often control crabgrass by keeping the surrounding grass higher and shading out any newly deposited seed. Crabgrass is an annual, so preventing seed spreading is key. You can use Corn gluten on established lawns to discourage germination. To prevent crabgrass from growing on new lawns, use a seed spreader and sow to the density recommended by your seed producer. You can also consider lawn alternatives like clover.
Dandelion
Every toddler’s favorite flower, the perennial dandelion is now well known as a nutritious edible spring green and an immune-boosting tonic. A few dandelions can be pretty, but if you find they are taking over your yard, you may have a calcium deficiency or an excess of potassium. Test your soil to find out the real culprit.
Dandelions also thrive in compacted soil, so consider renting an aerator if compaction is a problem. Aerators break up clods of soil, creating air pockets where other, more desirable plants can thrive.
Lastly, dandelions may be evidence that your soil is acidic. Once again, it’s worth testing your soil to know for sure. A comprehensive soil test from a lab can help you identify problems and recommend how much of a particularly amendment to add. To rectify acidic soil, apply dolomite lime according to your lab’s instructions. You can also use wood ash to make your soil more alkaline, but don’t apply more than every two or three years. Dandelions can actually help loosen earth with their long taproot, and bring up calcium from deep down to share with other plants—so they have their benefits! To help control them, however, you can mow your grass long (3+ inches) to shade the leaves, and correct your soil’s imbalances and texture. Over time the mature dandelions will weaken and your vigorous grass will out compete any new seedlings.
Annual bluegrass
This tuft-like grass produces abundant seed even when mowed closely. It grows well in shady spots but needs lots of moisture to thrive. Causes for its presence in your lawn could include low mowing height and over-frequent watering (this also applies to bentgrasses, another seedy tufted invader). Generally an indicator of high fertility, annual bluegrass prevalence is sometimes corrected by aerating, since it grows well in poorly drained ground where conventional grass struggles.
To slow the spread of annual bluegrass, remove new plants immediately when they surface and before they go to seed. Overseed any open areas in your lawn with vigorous seed mixes and water deeply, but infrequently, to encourage plants with deeper root growth. Be sure not to share lawn mowers if annual bluegrass is in your area, since it spreads easily.
Black medic
Often mistakenly referred to as “yellow clover,” black medic belongs to the same genus as alfalfa. It is an annual or short-lived perennial and its presence in your lawn usually means a combination of the following conditions: nitrogen deficiency, dry (or quick-draining) soil, and general poor fertility.
Unchecked, this plant will lay foot-wide flat mats of spreading tendrils across your lawn. Top dressing with compost or an organic fertilizer will help improve your soil’s tilth and should reduce black medic to a harmless visitor. Before you attack it, however, consider that black medic is a favourite plant of honeybees. It also belongs to the legume family and has the important ability to fix nitrogen from the air and bring it into the soil.
Prostrate knotweed
Prostrate knotweed is a member of the buckwheat family that gets its advantage from early germination: it claims space and gobbles up resources before neighboring plants have even awoken. Any bare spots in your lawn or garden will be vulnerable to this low, tendrily plant, which can mimic grass upon first emergence.
Identify it by its thin, wiry stems and tiny leaves and small pink-to-purple flowers. Prostrate knotweed usually thrives in heavily compacted areas where wheel or foot traffic has eliminated habitat for other less tolerant plants. It also prefers acidic soil that’s low in fertility, so adding lime and compost will help eliminate the plant.
Chickweed
A tasty addition to spring , chickweed thrives in fertile, well-watered conditions. Chickweed overgrowth may be a sign that your lawn is poorly drained, over-watered, or your soil is overly dense and compacted. Aeration helps. Always wait between waterings until your lawn shows visible signs of drought stress, and then water deeply.
A tasty addition to spring salads, chickweed is a cool-season annual plant originally native to Europe. Grown for feeding to poultry and humans, chickweed spreads horizontally on leafy stems that usually join at a central root that’s easy to hand pull. It thrives in fertile, often disturbed, well-watered conditions. A chickweed overgrowth may be a sign that your lawn is poorly drained, over-watered, or that your soil is overly dense and compacted.
Aeration helps discourage this plant, as does manual removal, but any treatment for chickweed should take place before the plant has a chance to set seed and start its cycle anew. Always wait between waterings until your lawn shows visible signs of drought stress, and then water deeply. If you are battling a handful of chickweed plants, remember that variety is healthy and chickweed has been known to decrease insect damage to other plants. It’s also high in nitrogen, iron, and an excellent garnish.
Plantain
Although these tough little plants share their common name with the edible, banana-like fruit sold in supermarkets, they are nothing like the plant indigenous to the tropical regions of Southeast Asia. Instead, the weedy plantain digs its taproots where nothing else can grow: driveways, sidewalks, footpaths. With lots of traditional healing uses, it’s handy to have a few plantain leaves growing near to apply to a wasp or nettle sting; children are soothed by the ritual of chewing the leaf to make a poultice.
If the plantains in your lawn are outperforming the grass, soil fertility is low and density or compaction may be high. Try the screwdriver test to see if aeration is needed: if you can’t easily plunge a screwdriver up to the handle into your lawn, it’s too dense. Look into significant compost mulching and aeration, and mow high to shade out plantain. You can add plantain clippings to your compost to increase its nutrient content. High acidity is also likely, but you can know for sure by performing a soil test. Amend acidic soil by adding lime.
Red sorrel
Another member of the buckwheat family, red sorrel (also called sheep sorrel) is an indicator of acidic conditions. It will quickly colonize disturbed areas by seed or extensive horizontal roots, even if the soil is very low in nutrients, since it likes nothing better than a niche waiting to be filled.
Thick colonies of red sorrel are found in depleted sites like abandoned mines, though the plant will also thrive in nutrient-rich soil when there is no competition. It has two germination cycles each year, one in spring and one in early autumn. If you improve your soil’s fertility, regulate over-acidity with lime, and plant something to fill in any gaps, red sorrel should subside.
Violet
If you’re finding yourself gathering sweet little bunches of violets more often than you’d wish, it will probably come as no surprise that your lawn is shady and wet. Drainage can be improved, but shade is often not correctable. With shaded lawns, it’s especially important to avoid mowing too low, since the grass takes longer to recover.
It’s also important to improve the overall health and vigor of your lawn. Make sure you’re using a grass well suited to your site: fine fescues will compete better in this situation than Kentucky bluegrass, and will soon choke out violets when well tended. You can also consider leaving the violets in place as you work towards a healthier lawn.
Dock
This leafy perennial is hard to ignore, with big coarse leaves that sprout up fast and high if you miss a mowing or two. The flower stalk is a towering, prehistoric-looking brown spindle with leaves long known for their healing properties.
Dock grows in acidic, wet conditions, and loves bare, disturbed soil such as the edges of fields, overgrazed pastures, and in gateways. Liming and improving drainage are long-term solutions to reducing dock; meanwhile, cut back often to prevent seed production. Seeds are viable up to 50 years!
Existing plants will die after three to five years, so vigilant mowing is a good alternative to laborious digging of deep root systems. Be persistent about keeping bare patches covered to reduce germination of new plants.
Oxeye daisy
Too many daisies of any variety indicate mild acidity, and Oxeye in particular, is a sign of seasonal sogginess. Like all species that reproduce only by seed, the daisy is dependent on available space for germination. Conditions leading to bare patches or insufficient density of grass provide an opportunity for daisies to multiply. Ensure your lawn or garden has as few bare patches or disturbed areas as possible. Reseed if necessary with regionally appropriate grass seed to provide the necessary density to crowd out seed-borne weeds.
Mulch exposed soil in garden beds. Beware of imported soil from other people’s gardens since this daisy has been known to survive such soil-moving operations. Correct poor fertility with amendments tailored to your soil test and aerate where sogginess rears its head.
White or red clover
Too much clover? Your chlorine, magnesium, and sodium are all likely to be high. Over-enthusiastic clover is also a sign of nitrogen deficiency, because this helpful weed is one of the few plants that can fix its own nitrogen and thereby contribute that essential nutrient to your depleted soil! It also stays green in drought conditions longer than grass and needs no fertilizer.
For these reasons, clover is often deliberately added to organic lawns, especially in areas where nitrogen-depletion is common. It developed the reputation of a weed because chemical herbicides kill clover, leaving unsightly bare patches. But clover is a friend to bees and adds important diversity to your lawn. If you’d rather it didn’t take over, however, increase your lawn’s fertility with compost. This will give your grass a hand and help it outcompete clover companions.
Yarrow
Traditionally used to heal cuts and stop menstrual cycles, yarrow was rumored to accompany Achilles into battle to staunch wounds. If you find too much vigorous yarrow in your yard, potassium and moisture levels are probably low and temperatures high; this hardy, sweet-scented perennial grows in poor, dry soil and loves the heat.
In fact, in drought-ridden California, some people are experimenting with deliberately planting a “yarrow-lawn” as a low-maintenance grass-alternative. (The cultivated plant comes in a variety of showstopping colors.) If your area is experiencing prolonged drought, consider this or other xeriscaping alternatives to opt-out of the worsening stress of maintaining thirsty grass in a water shortage.
Another promising option is drought-tolerant grass such as Eco-Lawn. Although yarrow won’t tolerate wet soil, it will appreciate nutrients and will grow enthusiastically if fertilized. Control by hand pulling or shading while you wait for amendments to improve soil condition.
Earth-friendly lawn care tips
If your favorite (or least favorite) weed is not featured here, check the links below to find out more. Regardless of the specifics of your terrain, all lawns benefit from a few earth-friendly tips:
- Test your soil if you’d like more details about how to work with what you’ve got. A pH of 6.0-7.0 is ideal for lawns.
- While you wait for your grass to strengthen and compete with the weeds, consider hand-digging or topping weeds to avoid seed production, which can lengthen your struggle by years.
- Mow high, mow often: adjust your mower to leave at least 3 inches of grass. You’ll get healthier root systems, less thatch, and shade to weaken low weeds.
- Wait to water until your lawn looks thirsty: the color should dull and footprints should stay compressed for more than a few seconds. When you do water, put a cup in the sprinkler zone and wait for 1” of water to accumulate.
- If your lawn is too dense to sink a screwdriver, talk to your neighbors about renting an aerator together to save money.
- Corn gluten, applied to established lawns in early spring, wards off many weeds by preventing germination, while nourishing grass through moderate nitrogen gain. Avoid corn gluten when reseeding.
- To enhance your mowing experience and lower your lawn’s carbon footprint, switch to a reel mower.
- Once the soil and grass are healthy, try to develop a tolerance for the occasional weed volunteer. Remember, a blooming lawn attracts and supports beneficial insects like butterflies and bees. Without pollinators— widely threatened by pesticides, climate change, and habitat loss — human civilization in its current form would be unable to sustain itself. By avoiding poisonous weedkillers, you’re reducing the damage to pollinators, as well as people and pets.
Since an English engineer named Edward Beard Budding invented the lawn mower in 1830 (mechanizing a process that had previously been accomplished by grazing animals or servants with scythes), the cultivation and maintenance of our household lawns has become a national preoccupation. It’s the view out of our living room windows, a soft place for our children to romp, a carpet for our summer barbecues and a backdrop for our personal ideas of domestic beauty. Though more and more Americans are feeling the pressures of climate change and rethinking the lawn’s primacy, for many of us the lawn remains central to our daily routines. Luckily, in most climates there are sustainable ways to keep and maintain this treasured play-space.
In lawn-care as in life, we strive to strike a balance. The healthier your soil, the more naturally luxurious your lawn will become. Listen to your lawn, approaching each weed in a spirit of curiosity and collaboration. The pay-off: less toxic chemicals, greater understanding of your ecosystem, and less yard work in the long run.
Resources:
Natural Lawn Care: Tips and non-toxic products for a healthy yard
Weed Library: National Gardening Association
Weeds as Soil Indicators: Mother Earth News
National Coalition for a Pesticide-Free Lawn: Read your “Weeds” Guide
