When your sink doesn’t drain, there’s probably a clog. When there’s a fist-sized hole in your teenager’s room’s drywall, there isn’t much mystery surrounding the cause. However, when your lawn starts dying, there could be any number of factors influencing its current state: too much or too little sunlight, too much or too little water, lack of nutrients, pests and fungus, etc. 

Ultimately, if your lawn is suffering in a serious way, you should hire lawn care professionals to diagnose your problem. However, if you are educated about your lawn — what each problem looks like, how to solve it and how to prevent it in the future — you might be able to avoid this expense. To that end, here’s a guide to everything that could possibly go wrong with your lawn.

Sunlight

Like any plant, grass performs photosynthesis to create energy to grow and thrive, which means your lawn needs sunlight to survive. As you might expect, too little sunlight causes grass to starve because it lacks the energy source it relies on — but too much sunlight can also cause harm. 

When the lawn receives too much sunlight, it becomes overheated by the infrared rays and shuts down its photosynthetic process, no longer creating energy.

Your grass can receive a sunburn just like you can, meaning its cellular DNA can be damaged and require repair before normal growth can continue.

The stress of being overheated and sunburned also causes grass to become more susceptible to pests and diseases, and even normal maintenance, like mowing, can amplify the stress, causing grass to go further into shock or die.

Sunlight and shade damage are relatively easy to identify because they will occur in the sunniest or shadiest parts of your yard, respectively. It’s not uncommon to see a bare patch of dirt around the base of a tree or near a covered patio, where the shade is darkest.

Likewise, if you notice your lawn turning yellow and dying in the center, where it receives no shade, it’s safe to say your grass is burning from too much sunlight.

Exactly how much sunlight your lawn requires will depend on the variety of turfgrass in your yard. Typically, warm-season grasses, like Bermuda, zoysia and St. Augustine, can tolerate more sunlight whereas cool-season grasses, like bluegrass, ryegrass or fescue, prefer less. You can gain control over the sunlight shining on your lawn using broad shade trees. With judicious trimming, you can allow enough light to shine on your lawn but prevent scorching — and you can create healthy airflow through your trees, too.

Water

Like sunlight, water is a fundamental requirement for lawn health, and also like sunlight, providing water seems like an intuitive process to most homeowners. Unfortunately, most homeowners get watering very, very wrong and end up damaging their lawn over time. Too little water will leave your lawn parched and unable to perform the processes that keep it alive and thriving, while too much water will drown your lawn, preventing it from accessing other nutrients it needs. 

However, the problem isn’t usually how much water you give your lawn; it’s how you administer the water that matters.

This is because the amount of water your lawn receives is largely dependent on other factors, like air and soil temperature, sunlight, soil composition and more. If you live in a warm region and sprinkle a small amount of water on your lawn every day, it’s likely that much of that moisture evaporates before it can reach your lawn’s roots.

In contrast, if you live in a cooler, wetter place, the soil around your lawn might already be saturated with water, and watering more could create a swamp-like environment that encourages the proliferation of disease and rot.

Usually, this damage occurs in small patches where your sprinklers miss or where water pools. You should work to ensure that your lawn is watered evenly by monitoring where the water falls when it leaves your sprinklers and where it runs across your soil.

Your lawn needs roughly 1.5 inches of water per week — perhaps slightly more or less depending on factors unique to your yard.

This water is best administered in one or two long, slow waterings per week, which allows the moisture to sink deep into the soil, where roots can access it and where the sunlight and heat can’t cause it to evaporate. You can perform the tuna can test or use rain gauges to better understand how much water is reaching your lawn and where.

Fertilizer

Sunlight and water are two major components of a healthy lawn, but if you are skipping the annual application of fertilizer, you are depriving your lawn of critical nutrients.

In recent decades, turfgrass has become a monoculture, meaning you likely only have one variety of groundcover as opposed to several, which is how lawns began.

While this creates a classic, even-looking lawn, it also means your grass is stripping your soil of a few key nutrients, specifically nitrogen, phosphorus and potassium (or “potash”).

Each of these components is critical for lawn health in a different way: 

• Nitrogen is an essential part of chlorophyll, which is used in photosynthesis. Thus, nitrogen is associated with the growth of leaves. Lawns that are struggling to grow dense and green often struggle from insufficient nitrogen.
• Phosphorus helps the plant absorb other macro- and micronutrients. If your lawn looks sparse, grows exceedingly slowly or seems to have a purplish cast, it could need phosphorus.
• Potash has a number of roles within plant biochemistry: regulating CO2 uptake and water usage, synthesizing starches for the creation of energy, activating growth enzymes and more. Again, stunted growth can be a sign of potassium deficiency, but you should also look for yellowed edges on blades of grass as well as rapid damage from drought and heat.

Important and expansive lawns, like those on golf courses, are fertilized as frequently as every week or month, but experts say that residential lawns likely only need fertilizing once or twice per year, in spring or fall.

In fact, you should avoid over-fertilizing your lawn because excess nitrogen and potash can have the opposite effect, burning your lawn and causing unsightly damage.  Because there are so many different kinds of grass fertilizers — and so many tools to administer fertilizer — you might want to outsource this lawn chore to professionals.

Pests and Disease

Finally, even the healthiest lawns can succumb to pests and disease, which feed on your grass or compete with it for vital nutrients.

Unfortunately, it’s impossible to explain every potential pest and illness that can affect your lawn; there are potentially hundreds, and they are highly dependent on region and climate. Instead, we’ll focus on the most common of each category:

Pests

• Chinch bugs are about the size of a pencil tip and have an hourglass design on their backs. They suck the sap out of blades of grass, leaving your lawn looking wilted.
• Sod webworms are light-beige moths that, in their larval stage, chow down on the stems of your grass near the soil. The damage isn’t obvious until the lawn goes dormant, but you can identify webworms by seeing the adults flying around your best lawnmower or by the dense webs near the crown.
• Cutworms are essentially caterpillars — fat, green, one-inch-long larvae — that slice the stems of new seedlings. If you see one or two cutworms in your lawn, you don’t need to panic, but a larger number of them can be a plague that devastates not only your lawn but your entire landscape.
• Billbugs are weevils that lay their eggs in dormant lawns during winter. The larvae then feast on new growth in spring, killing the grass. Identifying this pest can be difficult due to their teensy size and the damage, which is often conflated with other issues.
• White grubs are the larvae of scarab beetles, which feed on grass roots, making it impossible for your lawn to get water. If your grass rolls back like a carpet — or if you see white grubs in the soil — you have an infestation.

No matter what kind of pest is devastating your lawn, you need professional help. Annual administration of pesticide is key for keeping pest populations at bay, but you should also work toward keeping your lawn as healthy as possible, so if pests move in, they won’t kill your grass outright.

Disease

It’s worth noting that most lawn diseases aren’t viruses or bacteria. Instead, lawn diseases tend to be fungi, which flourish in moist soil and feed off already unhealthy grass.

Unfortunately, once a lawn disease takes hold, it tends to be rather difficult to eradicate.

A smarter practice is applying fungicide as a preventative measure once or twice per year if you live in a region where lawn disease is rampant.

• Brown patch grows when temperatures start warming to 65 and 70 degrees Fahrenheit in early summer. It is a common disease that manifests as small brownish-yellow blotches of dead grass.
• Large patch festers in the spring or autumn under moist conditions, growing swiftly from baseball-sized spots to dead patches larger than your car. The dead areas tend to be dark brown and might have regions of healthy grass floating in the middle.
• Pythium blight is technically a mold that grows in small, near-perfect gray or white circles. Pythium requires exceedingly damp conditions, including high humidity in the air.
• Pink snow mold grows where it is cool and moist for an extended period. As its name suggests, this disease appears pink for a brief period before turning white or light gray and eventually bleached tan once the grass dies.
• Summer patch is the sneakiest disease on this list because is does damage in late spring but can’t be detected until late summer. Asymmetrical circles or rings of tan or brownish turf are the main symptoms.

You might need a lawn professional to tell you what’s wrong with your lawn right now — but if you work hard to keep your lawn healthy, you might never need to diagnose lawn problems again. The key is knowing how to balance nutrients like sunlight, water and fertilizer and being diligent with pesticide and fungicide. The more you know about what your lawn needs, the less confused you will be if something does go wrong.