Purple Grass?! What’s Going On? How to Get Your Green Lawn Back

If you’re staring at a purple lawn and wondering if your grass is auditioning for a Prince tribute band, don’t panic. Purple grass isn’t permanent. The most common causes are cold stress (photoinhibition), nutrient deficiencies (phosphorus being the big one), fungal disease, water stress, mower/herbicide/traffic damage, and rarely, insect damage. Once you identify the cause, you can fix it — and with the right care, your grass will bounce back to green.

Why Is My Grass Turning Purple?

A healthy lawn should be green, lush, and the kind of turf you can’t resist walking barefoot on. But sometimes, instead of that rich green, you notice a purple tint sneaking across your yard.

So, why is your grass turning purple?

First, purple grass is a symptom, not a disease itself. It’s pretty common, especially in spring and fall, and while it looks alarming, it’s usually your lawn’s way of calling for help.

Here’s the breakdown of the most likely causes of purple grass, ranked from most common to least:

1. Cold Stress / Photoinhibition

2. Nutrient deficiency

3. Fungal diseases

4. Water stress

5. Mechanical and chemical stress

6. Insect damage.

Understanding which one is at play is the first step to fixing your purple lawn and getting your green back.

Cold Stress and Photoinhibition

This is the most likely culprit.

When soil temperatures drop below ~50°F (10°C), your grass struggles to take up phosphorus. Combine that with bright spring or fall sunlight, and you get photoinhibition — grass can’t use all that light energy, so it produces anthocyanins (purple/red pigments) as sunscreen.

Where you’ll notice it:

• Early spring after the snow melts

• Fall, during sudden cold snaps

• Shaded areas suddenly exposed to sun

• Newly seeded lawns or immature sod (shallower roots = more stress).

Good news:

This purple is usually cosmetic and temporary. Grass will green back up once temperatures stabilize.

What you can do:

• Be patient. Give it 1–3 weeks.

• Avoid heavy mowing or foot traffic when the grass is purple (it’s already stressed).

• Once daytime temps reach ~70°F and nights ~45°F, apply a light nitrogen feed to encourage green-up.
  For vulnerable new seed, you can even use shade cloths to soften light exposure during cold spells.

👉 If your lawn turned purple almost overnight after cold weather, this is almost certainly the reason.

Nutrient Deficiency and Phosphorus Problems

The second most common cause.

Grass needs phosphorus for strong roots and energy transfer. Without it, blades can take on a purplish tint. Cold soils can also mimic deficiency by locking up available phosphorus.

Signs of phosphorus deficiency:

• Purplish leaves (often starting at the tips)

• Thin, weak, or stunted growth

• Most noticeable in young grass or new sod.

Other nutrient links:

• Nitrogen deficiency can amplify purple tones by weakening chlorophyll.
  

• Potassium deficiency can leave grass stressed and more prone to discoloration.

Solutions:

1. Test your soil with a soil test kit.

2. If phosphorus is low, apply a fertilizer containing a balanced N-P-K formula (e.g., 14-7-14), such as Lebanon Complete 14-7-14 Fertilizer. It gives fast green-up (5-7 days) and deeper root development (due to the 7% phosphorus) and is suitable for both cool- and warm-season lawns.

 

lebanon-country-club-complete-fertilizer-14-7-14-sgn-80

 

3. Avoid overcorrecting — too much phosphorus can harm the environment.
   

4. Spoon-feed nutrients throughout the season for steadier growth. We highly recommend the Golf Course Lawn Carbon Kit. This is a soil amendment/biostimulant kit (liquid) that includes products like “Release ZERO / 901C,” “Nutri-Kelp,” and “ByoSpxtrum.” It helps with nutrient uptake, soil biology, and stress resilience. It is especially good if phosphorus is present but uptake is low (for example, when soil is cold).

 

golf-course-lawn-carbon-kit

 

How to use them together / timing:

• If the soil test shows low phosphorus, apply the Lebanon 14-7-14 granular fertilizer at the recommended rate (e.g., per label / according to area). Water it in.
  

• Use the Carbon Kit during active growth periods to enhance root uptake and soil microbe activity, which helps the fertilizer work better.
  

• For cool-season grasses, do this in spring/fall; for warm-season grasses, early summer is good.

👉 If your purple grass persists beyond cold snaps or shows up in new turf, nutrient deficiency is a prime suspect.

The Fungal Culprits Behind Purple Grass

The third most likely cause is the one you need to act on quickly. If you’ve spotted a purple lawn and thought, “Well, that’s new,” fungi might be the guilty party. Not all lawn fungi appear as brown patches — some can give blades a purplish tint.

Red Thread Disease (Laetisaria fuciformis)

 

Appearance: Pink or purple threads at blade tips. Grass looks like it has tiny red hairs.

Conditions: Cool, wet weather + nitrogen deficiency.

Fix: Feed your lawn a little nitrogen boost and apply fungicide if needed.

 

Leaf Spot and Melting Out Disease (Drechslera and Bipolaris spp.)

 

Appearance: Purple-black spots that spread into blotches. Blades weaken and collapse.

Conditions: Humid spring/fall + stressed lawns.

Fix: Avoid mowing too short, improve airflow, and apply a systemic fungicide.

 

Snow Mold — Gray and Pink (Microdochium Patch)

 

Appearance: After snow melts, the grass has grayish or purple patches, sometimes with fuzzy mold.

Conditions: Cool, damp weather (32–60°F). Or extended snow cover on unfrozen ground.

Fix: Rake matted areas, aerate in fall, and apply preventive fungicides with propiconazole if winters are harsh.

 

Rust Diseases

 

Appearance: Purple cast before orange spores show up.

Conditions: Low nitrogen + late summer stress.

Fix: Balanced fertilization, regular mowing, and fungicides if severe.

 

How to spot fungus:

• Purple appears in patches or streaks, not evenly across the lawn.

• You may see fuzzy growth, spotting, or dead centers.

When a fungal disease causes purple grass, you’ll want strong fungicides. These are good fits:

• Pillar SC Intrinsic® Brand Liquid Fungicide — Brown Patch and Dollar Spot Control — A fast-acting liquid combo fungicide that controls many diseases, including leaf spots, fusarium, red thread, etc. It is great for quick knockdowns.

 

pillar-sc-fungicide-liquid-brown-patch-and-dollar-spot-control

 

• Headway G Granular Fungicide — Granular fungicide (azoxystrobin + propiconazole) is good for preventative or curative uses over larger areas.

 

headway-g-fungicide-granular

 

• Caravan® G Insecticide and Fungicide — A dual-action product that helps with both fungal issues and some insect pest pressures. Useful if you suspect insects might be compounding the stress.

 

caravan-g-insecticide-and-fungicide

 

How to choose and timing:

• If disease spots are already present and spreading → use Pillar SC Intrinsic® Brand liquid first for quicker effect.
  

• Use Headway G granular when you want residual protection or treating large areas, especially ahead of conditions favourable to fungus (cool + damp).
  

• Caravan® G helps cover both problems if your lawn has insect pests simultaneously.

Purple Grass Water Stress Symptoms

Fourth in the ranking — but easy to fix once you know.

Grass turns purple when:

• Too dry → drought stress triggers anthocyanins.
  

• Too wet → roots suffocate and nutrients can’t get in.

Signs of drought stress purple:

• Brittle and crisp blades

• Purple in localized dry spots

• Lawn bounces back after deep watering.

Signs of overwatering purple:

• Mushy soil underfoot

• Purple discoloration across low spots

• Grass looks limp, not crisp.

Fix:

• Water deeply but infrequently (about 1 inch per week).

• Probe the soil before watering. If it’s damp 2–3 inches down, hold off.

• Improve drainage in soggy areas.

👉 If your purple patches line up with irrigation zones or puddle spots, water stress is the issue.

Mechanical and Chemical Stress Factors

Fifth in the ranking — less common, but often overlooked.

Mower Injury

• Dull mower blades shred grass, which can show purple bruising.

• Scalping (cutting too short) stresses turf, exaggerating discoloration.

Herbicide Stress

• Some herbicides cause a temporary purple tint if misapplied.

• Overdosing, spraying in extreme temperatures, or drift can all trigger stress.

Traffic Stress

• Heavy foot traffic, pets, or equipment can bruise blades and compact soil, leading to purple discoloration.

Fix:

• Keep mower blades sharp and cut at the right height.

• Always follow herbicide label rates and timing.

• Rotate traffic zones and aerate compacted areas.

👉 If your purple grass looks like mower tracks, pet paths, or spots you sprayed, this is your culprit.

Insect Damage and Purple Turf

Least common, but worth mentioning.

Pests like billbugs, chinch bugs, and grubs usually cause brown patches, but early feeding can stress turf enough to cause purplish discoloration.

Signs:

• Grass thins quickly after turning purple

• Turf pulls up easily (grubs)

• Birds pecking at the lawn (feeding on insects).

Fix:

• Inspect the soil for grubs or pests.

• Apply targeted insect control products like Acelepryn G Granular Insecticide if confirmed.

 

acelepryn-g-insecticide-grub-and-armyworm-control

Purple Grass Troubleshooting Guide

Cause	What It Looks Like	What to Do
Cold Stress / Photoinhibition	Whole lawn or patches turn purple after a cold snap, especially in spring/fall. Often temporary.	Be patient. Avoid stress (traffic/mowing). Once temperatures stabilize, apply light nitrogen for green-up.
Nutrient Deficiency (Phosphorus)	Purplish leaves, especially in young/new turf. Thin, weak growth. Doesn’t correct with warmer temps.	Soil test. Apply phosphorus-rich fertilizer (e.g., 14-7-14). Balance N-P-K for overall health.
Fungal Diseases	Patches or streaks with purple, reddish, or purplish-gray discoloration. May show fuzz/spots.	Apply fungicide early (propiconazole, azoxystrobin). Bag infected clippings. Improve airflow & mowing.
Water Stress	Drought: brittle, dry, purple blades. Overwatering: limp, purple, soggy areas.	Water deeply but less often. Improve drainage. Probe the soil before watering.
Mower Injury	Purple tracks or blade tips after mowing. Scalping or dull blades worsen it.	Sharpen mower blades. Raise the cutting height. Avoid mowing stressed grass.
Herbicide Stress	Purple discoloration in sprayed areas. Usually temporary.	Always follow label rates. Spray in mild weather. Avoid drift.
Traffic Stress	Purple patches in play areas, pet paths, or high-use zones.	Rotate traffic areas. Aerate compacted spots. Overseed thin turf.
Insect Damage	Grass turns purple, then thins or dies. Turf pulls up easily; birds pecking at the soil.	Inspect for pests (grubs, billbugs). Apply targeted insect control if confirmed.

Grass Types Most Susceptible to Turning Purple

Not all grasses handle stress the same way. Some species are more prone to showing purple discoloration when conditions get tough. If your lawn seems to blush purple every spring or during drought, your grass type might be partly responsible.

Cool-Season Grasses

Cool-season turf like Kentucky Bluegrass, Ryegrass, and Fescues are more likely to develop purple discoloration in early spring and fall when temperatures drop. Why?

• Cold soil limits phosphorus uptake.
  

• These grasses often show anthocyanin buildup (purple pigments) during photoinhibition.
  

• Kentucky Bluegrass, in particular, is known to flash purple when stressed.
  
  

 

Related: How to Rid Kentucky Bluegrass of Poa Annua

 

Warm-Season Grasses

Warm-season varieties like St. Augustine and Bermuda can also show purple tints, but usually for different reasons:

• St. Augustine is prone to purple under nutrient deficiencies, especially phosphorus.
  

• Bermuda grass sometimes takes on a reddish-purple cast in winter dormancy or under drought stress.

Newly Seeded or Immature Grass

Regardless of type, immature turf is more sensitive:

• Shallow roots = less access to nutrients.
  

• More vulnerable to cold snaps and mower injury.
  

• More likely to accumulate anthocyanins and show purple stress colors.

Takeaway

If your grass type is naturally prone to purple stress responses, don’t panic. It doesn’t mean your lawn is unhealthy — it just means you’ll need to stay on top of nutrition, watering, and seasonal care to keep it greener for longer.

How to Fix Purple Grass

So, how do you fix purple lawn grass? Here’s a step-by-step approach:

1. Identify the cause. Start with soil testing, visual inspection, and reviewing your watering habits.
   

2. Address the fungus if present. Apply fungicide early before it spreads.
   

3. Correct nutrient deficiencies. Feed your lawn what it’s missing (phosphorus or other nutrients).
   

4. Optimize watering. Deep soak when needed, but avoid waterlogging.
   

5. Aerate if compacted. This helps nutrients and water move into the root zone.
   

6. Overseed bare spots. If purple damage has thinned your lawn, overseeding will help it recover faster.

 

Related: Aeration and Overseeding: Why These Two Practices Go Hand-in-Hand for Optimal Lawn Health

 

How to Prevent Purple Grass in the Future

Prevention beats cure every time. Here’s how to keep your grass green and avoid purple surprises:

• Regular soil testing: Catch nutrient issues before they show up in color changes.
  

• Balanced feeding: Use high-quality fertilizers and spoon-feeding for consistent nutrition.
  

• Proper mowing: Don’t scalp your lawn; keep it at the recommended height for your grass type.
  

• Water smart: Deep and infrequent beats frequent and shallow.
  

• Fungus watch: Apply preventative fungicides during peak risk times.
  

• Aerate annually: Reduce compaction and improve soil health.

 

Related: Lawn Rescue after Heavy Rain and Fungus Attacks.

 

Weeds That Make Lawns Look Purple (But Aren’t Grass Problems)

Sometimes what looks like a “purple lawn” isn’t your grass at all — it’s weeds sneaking in and adding their own splash of color. A few common lawn weeds produce purple flowers or foliage that can make whole patches of turf look purple from a distance.

Henbit (Lamium amplexicaule)

 

A winter annual weed in the mint family. It pops up in early spring with tiny purple flowers on upright stems. When it carpets parts of a lawn, it creates the illusion of purple grass.

 

 

Purple Deadnettle (Lamium purpureum)

 

Close cousin to henbit. It has purplish leaves near the tops of stems and purple flowers. Deadnettle loves cool, damp conditions — often seen blooming alongside henbit.

 

 

Wild Violet (Viola spp.)

 

A tough perennial with heart-shaped leaves and bright purple flowers. It spreads by seed and rhizomes, and is one of the trickiest lawn weeds to eradicate. Grows in shady, moist areas where grass is thin.

 

 

Creeping Charlie / Ground Ivy (Glechoma hederacea)

 

A creeping perennial with scalloped leaves and bluish-purple flowers in spring. Spreads aggressively by stolons, quickly overtaking weak lawns. Large patches can give the impression of a purple haze across your turf when in bloom.

 

To address weeds that mimic or exacerbate the purple-looks issue:

• Celsius and Certainty Herbicide Kit with Surfactant and Dye (Warm-Season Grass)— Good for a broadleaf post-emergent + selective grass weed control, with surfactant (helps coverage) and a dye (for easy visual application).

 

celsius-and-certainty-herbicide-kit-with-surfactant-and-dye

 

• Tenacity and SedgeHammer® Herbicide Kit with Surfactant and Dye (Cool-Season Grass) — Use this if you have cool-season turf and need to knock out sedges / tougher weeds plus general weed control.

 

tenacity-and-sedgehammer-herbicide-kit-with-surfactant-and-dye-cool-season-grass

 

Usage tips:

• Apply herbicides when weeds are actively growing and conditions are mild (avoid extremes of heat or cold), so product uptake is good.
  

• Always apply according to the label for your grass type: cool-season vs warm-season.
  

• Follow up with good lawn practices: Ensure that the grass is healthy and dense so that weeds have less of a chance to dominate.

Related: Lawn Weeds with Purple Flowers

 

FAQs About Purple Lawns

Q: Why is my grass turning purple just in spots?
A: Likely fungus or localized nutrient deficiency. Check for patterns and soil conditions.

Q: Is purple grass permanent?
A: No. You can restore a rich green color with the right diagnosis and care.

Q: Does purple grass mean my lawn is dying?
A: Not usually. Purple is more often a stress signal than a death sentence. Most lawns recover once the underlying issue — cold, nutrients, water, or fungus — is addressed.

Q: Will phosphorus deficiency fix itself?
A: Not usually. Unlike temporary cold stress (which can look similar), a true phosphorus deficiency won’t resolve on its own. If your soil is genuinely low in phosphorus, the grass won’t be able to grow strong roots or green up properly until you supply it. The best approach is to confirm with a soil test, then apply a balanced fertilizer that includes phosphorus, such as Lebanon Country Club Complete 14-7-14. Once corrected, you’ll usually see improvement in 10–14 days.

Q: Can dog urine cause grass to turn purple?
A: Dog urine usually causes yellow/brown spots, not purple. If you’re seeing purple patches, the cause is more likely cold stress, nutrient deficiency, or fungus.

Q: Why is only the tip of my grass blade purple?
A: That’s often mower stress (dull blades shredding instead of cutting cleanly) or mild nutrient stress. A soil test and mower blade sharpening usually solve it.

Q: Why is my grass turning purple after fertilizer?
A: Fertilizer applied in cold weather can’t always be absorbed properly, which may trigger temporary purple discoloration. It should clear as temperatures stabilize. Over-application or imbalance (too much nitrogen without enough phosphorus) can also exaggerate purple hues.

Q: Can too much shade make grass purple?
A: Indirectly. Grass in shade is weaker and slower to grow, showing stress colors like purple more readily. It’s not the shade itself, but the added stress.

Q: Is purple grass harmful to pets or kids?
A: No. The purple color is a pigment response, not a toxin. The only concern is if fungus is present — while most lawn fungi aren’t dangerous, some can cause stomach upset if ingested. It’s always best to treat fungus quickly.

Q: Does purple grass mean I need to overseed?
A: Not always. Overseeding isn’t necessary if purple grass recovers with nutrients, fungicide, or better watering. But if purple areas thin out or die off, overseeding is the quickest way to restore coverage.

Q: Will purple grass come back next year?
A: If the cause is cold stress, yes — it may reappear every spring/fall. But with consistent feeding, aeration, and proper watering, it’s often less noticeable year after year.

Q: Can soil pH cause grass to turn purple?
A: Yes. Very acidic soils (low pH) can lock up phosphorus, making grass show deficiency symptoms even if phosphorus is present. A soil test will confirm if lime is needed.

Q: My neighbor’s lawn is green, but mine is purple — why?
A: It often comes down to grass type, soil fertility, and microclimates. Even next-door lawns can react differently to the same weather.

 

From Purple Blues Back to Green Dreams

A purple lawn might look like a disaster, but most of the time it’s just a stress signal. Whether it’s cold stress, nutrient deficiency, fungus, water stress, mower injury, herbicides, or (rarely) insects, the fixes are straightforward once you know the cause.

With the correct diagnosis, patience, and products, your lawn will return to lush green in no time.

Purple may be royal, but green is king in lawn care.

Ready to kick the purple and bring back that pro-level green? Browse the full range of lawn care products. And if you want step-by-step lawn care tips, subscribe to the Golf Course Lawn YouTube channel. It’s where I share the same strategies to keep my own lawn looking like a fairway.