Quick answer: Weeds fill gaps. The lasting fix is a dense lawn and covered beds, supported by a pre-emergent in early spring for crabgrass and targeted post-emergent treatments, with fall being the best season for broadleaf weeds.
Why do weeds keep coming back?
Weed seeds are always present in soil. They take hold where turf is thin or soil is bare. The usual causes are mowing too short, compacted soil, shallow daily watering, shade and bare mulch-free beds. Treating weeds without fixing those conditions means treating the same spots every year.
What is integrated weed management?
Integrated pest management, or IPM, means using every tool in the right order: prevention first, then cultural practices, then targeted treatment only where it is needed. For lawns and landscapes that looks like:
- Mow high. Keep cool season grasses around 3 inches or taller. Taller grass shades the soil and crowds out crabgrass.
- Water deeply, not daily. Deep, infrequent watering grows deeper roots.
- Overseed in early fall. It is the best window on Long Island to thicken thin turf.
- Mulch beds. A 2 to 3 inch layer blocks light from weed seeds.
- Test the soil. Correcting pH and fertility helps turf outcompete weeds.
When should pre-emergent go down?
Pre-emergent herbicides stop seeds such as crabgrass from establishing, so they must be applied before germination. On Long Island that means early spring, as soil temperatures approach the mid 50s. The traditional cue is forsythia in bloom. Applied too late, a pre-emergent does little.
When do post-emergent treatments work best?
Post-emergent products treat weeds that are already growing. Broadleaf weeds such as dandelion, clover and plantain are most vulnerable in fall, when they are moving energy down to their roots, with spring as the second best window. Spot treating visible weeds uses less product than blanket applications.
What about ornamental beds and hardscapes?
Beds need a different approach than turf, because many lawn products can injure shrubs and perennials. Mulch, careful spot treatment and bed-specific pre-emergents do most of the work. Pavers, driveways and fence lines are treated separately, with attention to runoff so product stays where it is applied.
Related: Green industry best management practices | Weed control services
This article is general information. Pesticides must always be applied according to the product label and New York regulations.