Digitaria ischaemum
grassy weedUSDA zones 3–9Active: summerSimilar to large crabgrass but with smoother, shorter blades. More common in northern regions. Same annual lifecycle dying at first frost.
Shorter and smoother than large crabgrass; less hairy stems and leaves; purple-tinged base; grows in star pattern.
Same approach as large crabgrass — maintain 3.5-4 inch height to shade soil.
When: Throughout growing season
Spring pre-emergent at 20 lbs per 1,000 sq ft.
When: Apply before soil reaches 55F (soil ≥ 55°F)
Same pre-emergent controls both crabgrass species.
When: Apply when soil temperature reaches 55F (soil ≥ 55°F)
Active ingredient: Prodiamine — e.g. Barricade
Effective post-emergent on young smooth crabgrass.
When: Apply to young plants with 1-3 tillers
Active ingredient: Quinclorac — e.g. Drive XLR8
Grass safety: always match herbicides to your grass species — products safe on Kentucky bluegrass can kill St. Augustine or centipede. Lawn Guardian checks this automatically against your lawn profile.
Lawn Guardian turns this guidance into a schedule timed to your USDA zone and this week's actual weather — and adapts every time you log what you've done.
Get your free plan