Common Lawn Weeds Identification Reference
Overview
Weed identification is half the battle. Different weeds need different chemistry - broadleaf herbicides don't kill grasses, grass-selective herbicides leave broadleafs. Wrong product = no result + customer dissatisfaction. This reference is the in-truck identification card for the 12 most common residential lawn weeds in U.S. cool-season + warm-season turf.
Reference Table
Broadleaf weeds (controlled with 2,4-D / dicamba / mecoprop blends):
| Weed | Identification | Best treatment time |
|---|---|---|
| Dandelion | Yellow flower, hollow stem, lobed leaves | Fall (root storage time) |
| White clover | Three-leaflet, white round flower, mat-forming | Fall preferred |
| Plantain (broadleaf or buckhorn) | Oval flat leaves with prominent veins | Fall or spring growth |
| Wild violet | Heart-shaped leaves, purple flower | Multiple fall applications |
| Chickweed (common or mouse-ear) | Small white star flowers, succulent | Early fall or spring |
| Spurge | Mat-forming, milky sap when broken | Summer (only growing season) |
| Henbit | Square stem, scalloped leaves, purple flower | Fall pre-emergent best |
| Ground ivy (creeping Charlie) | Round scalloped leaves, mint family, purple flower | Fall - hardest weed; multiple applications |
Grassy weeds (need grass-selective herbicides or pre-emergent):
| Weed | Identification | Best treatment time |
|---|---|---|
| Crabgrass | Wide flat blades, spreads horizontally summer | Pre-emergent at 50 - 55 °F soil temp |
| Goosegrass | Whitish stem base, rosette pattern | Late pre-emergent (warmer than crabgrass) |
| Nimblewill | Fine-textured perennial grass, dormant brown in fall | Spot-spray with glyphosate; reseed |
| Bermuda grass (in cool-season turf) | Stoloniferous, gray-green | Spot-spray with glyphosate or Fusilade; reseed |
Notes
- Pre-emergent timing is critical. Crabgrass pre-emergent applied AFTER germination is wasted product. Soil-temp monitoring (50 - 55 °F sustained) is the right trigger.
- Spot-spray vs broadcast: spot-spraying broadleaves cheaper + less customer-disruption than broadcasting. Broadcast only when broadleaves cover > 20 % of the lawn.
- Grass-selective herbicides (Fusilade, Acclaim, Drive) are species-specific. Read the label - Drive controls crabgrass + sandbur but not bermuda; Fusilade controls bermuda but not crabgrass.
- Glyphosate (Roundup) is non-selective; kills any plant. Use only for stoloniferous grass weeds in cool-season turf, then reseed.
- Customer education: weeds are a symptom of a thin lawn. A thick lawn outcompetes weeds. The long-term answer is overseed + fertilize + correct watering, not chemicals alone.
Safety
Herbicide drift onto customer's ornamentals causes visible damage within 7 days and is unrecoverable. ALWAYS use a spray shield, work in low-wind conditions, and document any nearby sensitive plants (vegetable gardens, prized perennials). The "I sprayed her lawn and now her tomatoes died" call is the most expensive call in lawn care.
Identification quick-tells
When you don't recognize the weed:
- Pull and examine the root system. Taproot = mostly broadleafs. Fibrous root = grass weeds. Rhizomes / stolons = perennial spreaders (bermuda, nimblewill, ground ivy).
- Crush a leaf + smell. Mint family (ground ivy, henbit) smells minty. Onion / garlic family smells obvious.
- Look at flowers. Composite (dandelion, hawkweed) vs solitary (clover) vs spike (plantain) narrows it down.
- Use an app. PictureThis, PlantNet, and similar apps identify > 90 % of weeds reliably from a photo.
References
- Extension-service weed-ID guides specific to your region
- Herbicide manufacturer label directions
- Manuall internal: Spring Lawn Startup Service, Lawn Brown Patches - Diagnostic Tree, Yellowing Grass - Diagnostic Tree