Why is This Lawn Patchy?

A lush, green lawn is the pride of many homeowners, but mysterious brown patches can appear, prompting you to seek answers. In the video, This Old House landscapers Roger Cook and Jenn Nawada discuss causes of dead lawn patches with host Kevin O’Connor. This article explores common causes of patchy lawns and offers solutions to restore your grass. 

Understanding Lawn Damage

In the case of this homeowner, accidental misuse of herbicide was to blame. However, that’s far from the only cause of a patchy lawn. Here’s what you need to know about lawn damage.

Common Causes of Patchy Lawns

Does your lawn look brown and patchy? The culprit is likely to be one of these:

• Drought stress: Insufficient water supply leads to dry, brown patches across the area
• Insect infestations: Grubs or other pests feed on grass roots, causing thinning and discoloration
• Fungal diseases: Conditions such as leaf spot or rust can lead to unsightly lawn blemishes
• Pet damage: Urine spots or digging can create dead patches, disrupting the lawn’s uniformity
• Improper mowing techniques: Cutting grass too short or with dull blades can weaken its resilience
• Chemical burns from fertilizers or herbicides: Over-application or incorrect product use may result in scorch marks on the lawn

The Dangers of Non-Selective Herbicides

An herbicide is any chemical used to kill a plant, and not all herbicides are alike. Selective herbicides kill only certain types of plants. The kind sold to homeowners usually targets weeds, such as the broadleaf weed killer seen in the video. However, non-selective herbicides, also called defoliants, simply kill every plant they touch. They’re useful if you need to clear land, but they can devastate a lawn when used improperly.

Proper Weed Control Techniques for Your Lawn

To avoid accidentally damaging your lawn while controlling weeds, use the right products and techniques.

Choosing the Right Herbicide

The homeowner here made a simple mistake, confusing one similarly-shaped bottle to another. Fortunately, this kind of mistake is easily preventable by choosing an appropriate herbicide to avoid harming your grass.

• Read labels carefully: Herbicide labels can be deceivingly similar. Double-check your selection to ensure it’s intended for lawn use.
• Use selective herbicides on lawns: These target specific weeds without affecting turfgrass, making them suitable to spray across your lawn.
• Use non-selective herbicides sparingly: Typically, you’ll only use these for areas like sidewalks or driveways, if at all.

Organic Alternatives

For those who prefer options with lower environmental impact, organic herbicides offer an alternative. However, the synthetic chemicals in traditional herbicides are what allow them to be selective. There are no selective organic herbicides. Common organic herbicides like vinegar, ammoniated soap, essential oils including cinnamon and clove, and citric acid will damage all plants they come into contact with. 

If you use organic herbicides, you must only apply them to plants you want to kill. Do not spray them on your grass or you’ll end up with a patchy lawn like the homeowner in the video. One application of an organic herbicide is unlikely to kill grass as completely as a non-selective synthetic herbicide, but it will damage anything plants it touches.

Note: In the video, Cook does state that clove-based PureDefense Weed Shield will only kill weeds, not grass. However, this product is no longer available for purchase, and clove oil is indeed a non-selective herbicide.

Best Practices for Herbicide Use

You’ll get the most out of herbicides by being mindful of safety and effectiveness during every application. Here are some straightforward guidelines:

• Wear gloves and closed-toe shoes to protect you from exposure during application.
• Wind can carry herbicides onto desirable plants, so choose a calm day for application.
• Follow all manufacturer guidelines regarding the amount to apply and how often to apply it.
• Keep children and pets away from treated areas for the specified safety duration.
• All herbicides, whether synthetic or organic, should be stored in cool, dry places out of children’s and animals’ reach.

Alternatives to Chemical Weed Control

Fortunately, your options aren’t limited to synthetic herbicides and non-selective organic herbicides. You can use these methods to limit weeds instead, though they require more time and effort.

• Hand-pulling: Though labor-intensive, this process effectively targets small areas and isolated weeds
• Flame torch: Long-handled, propane flame torches make quick work of weeds in driveways and sidewalks, but obviously they must be used with extreme caution
• Corn gluten meal: This pre-emergent organic herbicide can kill crabgrass seeds before they germinate, but it must be applied at precisely the right time

Pro tip: Some lawn care websites advise dumping boiling water on weeds. While boiling water will indeed kill many plants, weed or not, transporting and applying boiling water is risky and only effective for small weed patches. Simply pulling the weeds is safer, more effective, and almost certainly faster.

Repairing a Damaged Lawn

If your lawn has suffered damage from improper herbicide use or other factors, there’s hope for recovery. Here are some tips for repairing a lawn and preventing damage in the future.

Steps To Repair Herbicide Damage

If the culprit is herbicide misuse, follow these steps:

1. Allow a few weeks for the herbicide to dissipate from the soil and thoroughly evaluate the affected area.
2. Use an iron rake to remove dead grass and loosen the soil, ensuring a healthy base for new growth.
3. Apply a layer of compost to boost soil quality, then overseed with an appropriate grass seed mix to promote regrowth.
4. Water regularly, maintaining even moisture levels, and minimize foot traffic until the new grass is well-established.

Preventing Future Damage

To keep your lawn looking its best and prevent future issues, consider these tips from landscape designer Jenn Nawada.

• Maintain proper nitrogen levels: Balanced nutrition with compost or a slow-release organic fertilizer helps grass recover quickly from any damage
• Keep mower blades sharp: Dull blades tear grass, increasing vulnerability to disease
• Water wisely: Early morning watering when the lawn is dry reduces the risk of fungal growth
• Aerate annually: Fall aeration breaks up soil compaction, improving overall lawn health
• Choose climate-appropriate, disease-resistant grass varieties: Some grasses resist fungal diseases and other common problems better than others

• Apply mulch: A thick layer of mulch around plants suppresses weed growth and conserves moisture
• Let grass grow: Set your mower blades higher and allow grass to grow a little taller so it can outcompete weeds

Our Conclusion

Maintaining a healthy, weed-free lawn requires attention and proper weed control strategies. By choosing appropriate herbicides, applying them correctly, and taking preventative steps, homeowners can avoid patchy lawns.

Resources:

Expert assistance with this segment was provided by Nawada Landscape Design.

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