How to Kill Purple Deadnettle in Kentucky Bluegrass Without Hurting Your Lawn
Direct Agronomic Answer
To selectively kill Purple Deadnettle in Kentucky Bluegrass without damaging your turf, apply Tenacity (Mesotrione 40%), SpeedZone Lawn Weed Killer (2,4-D 28.57%, Mecoprop-p 5.88%, Dicamba 1.71%, Carfentrazone-ethyl 0.62%) when air temperatures are between 55°F and 85°F.
Fast-acting PPO inhibitors like Carfentrazone knock down Deadnettle within 24 to 48 hours even during chilly spring mornings.
1. Labeled Safe Herbicides That Kill Purple Deadnettle in Kentucky Bluegrass
| Recommended Product | Active Ingredient & Group | Application Temp (°F) | Surfactant & Mixing Protocol | Where to Buy |
|---|---|---|---|---|
| Tenacity EPA Reg. 100-1267 |
Mesotrione 40% Group 27 (HPPD Inhibitor) |
55°F – 85°F Rainfast: 6h |
Always apply with Non-Ionic Surfactant (NIS) at 1 tsp (5 mL) per gallon of water for post-emergent applications. Causes temporary white bleaching on susceptible weeds and turf tips. | Check Price at DoMyOwn View on Amazon |
| SpeedZone Lawn Weed Killer EPA Reg. 2217-833 |
2,4-D 28.57%, Mecoprop-p 5.88%, Dicamba 1.71%, Carfentrazone-ethyl 0.62% Group 4 + Group 14 (Synthetic Auxins + PPO Inhibitor) |
50°F – 85°F Rainfast: 3h |
Do NOT add surfactant. Adding NIS or MSO increases ester volatility and causes severe contact burn on desirable cool-season turf. | Check Price at DoMyOwn View on Amazon |
| TZone SE EPA Reg. 2217-920 |
Triclopyr 7.72%, 2,4-D 29.36%, Dicamba 2.22%, Sulfentrazone 0.66% Group 4 + Group 14 (Pyridine Auxin + Phenoxy + PPO Inhibitor) |
50°F – 80°F Rainfast: 3h |
Do NOT mix with surfactant when temperatures exceed 75°F. In cool spring or fall conditions (55°F–70°F), 0.5 tsp NIS per gallon improves waxy leaf penetration on Wild Violet. | Check Price at DoMyOwn View on Amazon |
3. Optimal Seasonal Timing & Temperature Thresholds
Apply post-emergents in February or March before purple flowers produce seeds.
Fall pre-emergent Prodiamine or Dithiopyr provides excellent preventative control.
4. Diagnostic Checklist: Confirm It Is Purple Deadnettle Before Spraying
- Upper foliage shaded in a distinct purple to bronze-red hue
- Heart-shaped to triangular leaves attached via slender petioles
- Square, hollow stems with pink-purple two-lipped flowers in early spring
Not 100% sure? Use our AI Photo Weed Scanner or review the full Purple Deadnettle Botanical Profile.