Lawn weeds (couch grass, clover, plantain): identifying and controlling them

Weeds are unwanted wild plants that interfere with human activities in fields, vegetable gardens, lawns, and beyond. They spread to new areas thanks to the wind, insects, animals, etc., which carry them. They generally grow quickly, are highly competitive, and can survive even under harsh conditions.

There is a wide variety of weeds, which we can classify according to various criteria. Based on the length of their life cycle, they are annuals, biennials, and perennials. Based on when they germinate, they are either spring-summer or fall-winter types, or they may be able to germinate in any season (in practice, this means you’ll find weeds in the garden all year round). Visually, you can distinguish between grassy and broadleaf weeds. We’ll revisit these concepts in the article, explaining how to identify them, what damage they cause to the lawn, how to prevent them, and—when necessary—how to remove weeds from the garden.

Identifying weeds

Knowing how to identify weeds means understanding their key characteristics—life cycle duration, seasonality, how they spread—and what stage of development they’re in. This is essential for developing an effective control strategy. You can use a plant identification app on your smartphone or consult a traditional guidebook with photos.

Grassy weeds have, as the name suggests, narrow, pointed leaves and produce flower spikes. They belong to the grass family (Poaceae, but also called Gramineae), so they resemble the grass species sown in gardens to form a lawn. Among them are crabgrass, couch grass, and bluegrass. Broadleaf weeds, on the other hand, stand out on the lawn with their large, flat leaves and colorful flowers, such as daisies, portulacas or purslanes, plantains or fleaworts, buttercups, dandelions, and clovers.

Annual weeds are extremely numerous; they live for 7-9 months and reproduce by seed. Biennials propagate in the same way, but live for more than 12 months and are less numerous. Perennials live for several years and propagate both by seed and through buds carried by specific parts of the plant that are buried or close to the ground (rhizomes, stolons, etc.). Going back to the earlier examples, annuals include crabgrass, purslane, and buttercup. Perennials, on the other hand, include daisies, plantain (Plantago lanceolata and Plantago major), dandelion, clover, and couch grass. Bluegrass can be annual (Poa annua) or perennial (Poa trivialis).

What damage do weeds cause in the lawn? A great deal, but their presence is inevitable. Therefore, rather than waging an all-out war against them, to a certain extent it is better to learn to live with them:

• They compete with the grass seedlings for space, light, water, and nutrients.

• They facilitate the spread of insects, pests—such as fungi—and diseases.

• They compromise the uniformity of the lawn: they often grow taller, have a different color, and sometimes form large, dense patches.

How to remove weeds from your garden

Annual weeds are the easiest to control: remove them before they go to seed, so they don’t return in subsequent years. Perennial weeds are the most problematic, and before they produce seeds, they must be removed along with the entire root—or better yet, with all the parts that allow them to multiply.

Simply mowing the lawn prevents weeds from flowering, and thus from producing seeds and spreading. Depending on the circumstances, you can use a riding mower, lawnmower, brushcutter, or robot mower. If the weeds are about to go to seed, it’s best to mow with a machine equipped with a collection system, such as a rear-discharge riding mower or a lawnmower.

With the same goal in mind—to limit the influx of seeds from outside as much as possible—we recommend keeping the areas surrounding your garden clean: ditches, meadows, overgrown areas, etc. Mow before the existing weeds go to seed. In this case, you can use, for example, a brushcutter, a wheeled brushcutter or flail mower, a side-discharge garden tractor, or an all-terrain garden tractor.

A lawn that is properly maintained in terms of mowing, watering, and fertilizing already has everything it needs to keep weeds at bay. At that point, to remove weeds from the lawn, simply pull them out—that is, remove them entirely, roots and all—either by hand or with the help of a small knife or a weed puller. It’s easy if they’ve just sprouted, but it becomes harder to do so with mature plants because they can snap easily. Pulling weeds is very effective for keeping perennial weeds at bay.

The lawn must be monitored, and weeding should be repeated systematically (and patiently) because weeds are everywhere: they’re an integral part of the ecosystem, regardless of the fact that they sometimes conflict with human interests.

Chemical weed control should be a last resort, not the first shortcut to take. In fact, it eliminates the symptoms without addressing the causes: we’ll discuss this further when we talk about weed prevention.

Let’s return to the distinction between grassy and broadleaf weeds. Selective herbicides target broadleaf weeds but not other plants, and they do not harm the grasses in your lawn. Conversely, to eliminate grassy weeds, you need a total—that is, non-selective—herbicide, which, unfortunately, risks damaging the lawn, which is generally composed of grasses.

A non-selective herbicide can be useful for killing weeds in specific areas of the garden when you have no other options. For example, along a paved path, where weeds are sprouting from the cracks. Or you can use it if weeds have taken over specific areas of the lawn, which need to be reseeded after weeding so the soil isn’t left bare. One herbicide you can use freely is pelargonic acid, because it doesn’t require a license. In addition to being effective against many weeds, it doesn’t pollute the environment and isn’t toxic to people or animals.

How to prevent weeds

As we’ve mentioned, a healthy, dense lawn defends itself against weeds, whereas a weak, sparse lawn will fall victim to them. Therefore, a large part of weed control relies on proper lawn maintenance. Preventing weeds involves ensuring that the grass is in a position to outcompete them. In fact, grass can be weakened by:

• Improper mowing

• Inefficient watering

• Unbalanced nutrition

• Fungal diseases

How should you mow the grass to combat weeds? By considering both the cutting height and the frequency of mowing. The grass should be cut high enough to delay the germination of additional weeds. If you keep it a little taller (6-7 cm), it provides shade, preventing weed seeds from germinating and young leaves from developing. Mowing too low has a negative impact on the lawn itself: it deprives it of an important resource for photosynthesis, weakens it by reducing root development, and thins it out, halting its spread.

Frequent mowing has a twofold effect: on the one hand, it stimulates the grass to grow denser, producing new shoots. On the other hand, it weakens broadleaf weeds by removing a certain amount of leaf surface area used for photosynthesis. For this purpose, a robot mower may be the most efficient solution.

Don’t deprive your lawn of nutrients when it needs them most, and at the same time, fertilize in a way that doesn’t benefit the weeds. If you have a lawn of cool-season grasses, fertilize when they grow the most—that is, in the spring and fall. Do not fertilize in summer, when cool-season grasses slow down; otherwise, the fertilizer will only benefit heat-loving weeds. If, on the other hand, your lawn consists of warm-season grasses, fertilize in the spring and summer, and limit fall fertilization to avoid encouraging fall- and winter-growing weeds. Warm-season grasses, in fact, grow vigorously in summer and go dormant in winter. In the fall, therefore, you can apply potassium, which helps strengthen the lawn’s defenses in preparation for winter dormancy.

Promoting grass growth at the expense of weeds is the principle to follow when watering the lawn as well. Apply generous amounts of water, allowing long breaks between waterings. This technique gives the lawn grass—which has more developed roots—an advantage, while stunting young weeds.

Prevent fungal diseases in the lawn, and treat them when prevention isn’t enough. The same management mistakes—in mowing, watering, and fertilizing—that trigger these infections can also make the lawn vulnerable to weeds.

Another factor that facilitates the emergence of both fungal diseases and weeds is compacted soil, a topic we discussed in relation to soil fertility. Some weeds, such as purslane and Poa annua, actually thrive in compacted soil. Compacted soil, on the other hand, is inhospitable to grass seedlings.

Most weeds thrive from spring onward, while their growth slows in the fall and, if they are annuals, they die off. Late summer is therefore an ideal time to eliminate as many weeds as possible and give the grass time to fill in the spaces previously occupied by weeds. Here are the steps we recommend:

• Mow the grass short and dethatch the lawn with the scarifier.

• Pull out the largest weeds and those that have formed clumps.

• Remove the grass clippings, thatch, and the weeds you’ve pulled out.

• If the lawn is thinning, overseed it to thicken it, spreading the seeds among the surviving grass plants.

• In the bare spots, reseed from scratch, choosing—just as you would for spot-seeding—seeds of varieties that germinate and grow quickly.

Speaking of lawns: has yours turned yellow? This could be caused by improper care or a fungal disease. Is it dotted with mounds of dirt? Here’s how to get rid of moles.

We’ll wrap up by recommending an article that provides an overview of how to eliminate weeds in the garden, vegetable patch, and countryside.