Summertime for cool-season grasses can be a very tricky and troublesome period for many lawn care enthusiasts. Between drought and heat stress, grubs and insects, brown patch disease and everything in between fertilizer and herbicide burn, the most common question(s) this time of year is, what wrong with my lawn? Why is my grass turning yellow? Why is my grass turning brown? My lawn was so green and lush on Memorial Day, but now it’s lost that dominating look.
This post will hopefully clear some things up and help you to start to diagnose different unattractive (non-green) colors in your lawn. Here’s a quick high-level snapshot:
- YELLOW GRASS: lack of Nitrogen and/or Iron, and can also indicate herbicide burn
- BROWN GRASS: Wide range, indicating lack of water, drought stress, dormancy, and signs of insect and grubs
- ORANGE GRASS: indicates fertilizer burn, specifically from excess Nitrogen
- WHITE GRASS: indicates fungus or disease, particularly powdery mildew
- GRAY GRASS: also indicates fungus or disease stress
- GRAYISH HAZY GRASS: indicates a stressed lawn due to mower height. Cutting the lawn too short causes this hazy discoloring
- RED GRASS: indicates red thread or pink patch
- BLACK GRASS: indicates excessive Iron (Fe) or black lawn fungus (Cladosporium)
Note: this list is not exhaustive, and is not designed to exactly identify or specify lawn issues. It is designed as a guide and starting point to help you self-diagnose your grass. To truly determine the root cause, you will also have to inspect individual blades of grasses (for specific fungus), the pattern of the discolored areas (circles like in dollar spot, irregular zig-zags like grub damage), looking at the thatch layer, and soil for water saturation or lack thereof.
You’ll also need to open your lawn care guide and look back at your notes for things like your last fertilizer feeding, any herbicide applications, and so on. Did you forget to apply fungicide prevention or grub control? Did you use a heavy hand when applying a post-emergent crabgrass killer? Was it the right herbicide for your grass type? Taking notes is very important, they can help answer these questions which will help you better diagnose the issues and possibly prevent the need for a full lawn renovation.
Some more details for the more (un)popular grass colors.
Why is my grass turning yellow?
- Lack of Nitrogen (time to feed your lawn)
- Lack of Iron (apply chelated iron)
- Herbicide burn
Yellow patches in the lawn can indicate herbicide burning. Going extra heavy, applying in the middle of a hot and sunny day, or applying the wrong herbicide can all point to the yellow grass. If it was spot-spraying, the yellow will be in isolated patterns; if it were blanket sprayed, it will be more even throughout the grass.
Light green, lime green, or yellowish grass can also tell you that your lawn is hungry. If there are no spots of yellow, but rather an overall hue of lime, yellow grass, you should consider applying a Nitrogen fertilizer that also contains iron. Look back on your lawn care guide and see when your last application was. Missing these two vital nutrients will single-handedly prevent your lawn from getting that dark green color that we all strive for.
Why is my grass turning brown?
- Lack of water, drought/heat stress
- Shallow roots, concrete or rocks under the surface
- Dead lawn debris, excess thatch
- Fungus or lawn disease
- Grub or insect damage
Click on the images in the gallery to see different colored lawns and the exact issues.
A brown-colored lawn can be the cause of many different things. For example, dog urine burns can also be yellowish/orange at first and eventually turn brown. Brown spot and dollar spot disease are also brownish in color. To narrow down the exact issues, you need to do a little bit extra.
First, you can inspect the individual blades of grass to truly identify a fungus/disease. You can see an example in the image gallery above.
You also need to look for a pattern. While these colors at a glance may be similar (even grub damage to a degree), it’s the pattern that’s going to help distinguish one from another.
- Dog pee is isolated rings of burn generally kills the entire grass to the grown and thatch later.
- Dollar spot are small random circles throughout the lawn
- Brown patch is similar patterns to dollar spot but larger circles
- Grubs/insects will be completely irregular patterns of dead grass – sometimes in zig zags.
Why is my grass turning orange?
- Fertilizer burn (Nitrogen)
- Dog urine, pee burn
Why is my grass hazy?
- Dull mower blades (tearing/shredding the grass tips)
- Lawn cut too short, or too much cut off at once
- Dead lawn debris, excess thatch
- Beginning drought/heat stress
Why is my grass turning red/pink?
- Red thread fungus
- Pink patch fungus
Why is my grass turning black?
- Black spores and fungus from a pathogen called Cladosporium (source)
- Applying too much Iron (Fe)
Additional steps to identify cause of a discolored lawn
- An AMS Soil Probe can inspect for water saturation, root depth and health, thatch layer, and soil type and quality
- A soil probe or a screwdriver can check for rocks or other obstructions under the soil that can prohibit root growth and/or become too hot and killing the grass
- A thatch rake can inspect for too much thatch, and excess dead lawn debris. Too much thatch and dead debris can prevent both water and fertilizer from getting into the soil.
- Inspecting individual grass blades can help identify specific fungus types
- Keeping a lawn journal of fertilizer, herbicide, and pesticide applications can help drill into grass discoloration issues
I hope you found this post helpful as a starting point to diagnosing your discolored lawn. If you have any comments or questions, I’d love to read your feedback in the comments below.