Monday, July 14, 2014

Weed Management Next to Sidewalks and Driveways

Weed management next to sidewalks is difficult for several reasons outlined below. These “hot spots” for weed invasion become quite evident during summer as weeds encroach and turf quality declines. The below section outlines some of the causes for hot spots and how to best manage weeds in these areas.
  1. Soils are shallow in these spots. During construction of sidewalks, patios, streets, and driveways extra gravel, concrete, and an occasional 2 by 4 get left in areas adjacent to concrete and asphalt and as a result often only 2-3 inches of soil is present in the 6-12 inches adjacent to pavement. This makes a poor growing environment for turf and a good one for many summer annual weeds.
  2. Soils are warm in these areas. Shallow soils warm more quickly and soils adjacent to asphalt and concrete are subjection to additional radiant heating. Warmer soils are ideal for the germination of summer annual weeds.
  3. Soils are compacted next to sidewalks and drives. Compaction from vehicle and foot traffic compacts soils next to paved areas and when soils are compacted, turf quality is reduced and weeds are increased.
  4. Turf is stressed in these areas. Because of shallow, compacted soils unable to hold moisture and allow for deep rooting and because of increased soil temperatures, cool-season turfgrasses struggle to grow well immediately adjacent to sidewalks, patios, streets, and driveways.
  5. Edging of sidewalks increases risk for weed invasion. While edging your drive and sidewalk makes your lawn and property look sharp, it also exposes some soil on the edges and provides a nice environment for germinating weeds (some of which need sunlight to germinate – and you just removed the turf that was shading the sidewalk edge). Edging your sidewalks in the fall when most weeds aren’t germinating will help reduce weed problems in these areas.
  6. Weeds grow well in these areas for the above four reasons. Yellow nutsedge, prostrate knotweed, prostrate spurge, purslane, crabgrass, goosegrass and more are common weeds in these areas.
Manage weeds in these areas by spot treating with the appropriate herbicides based on the weed population. Additionally, edging sidewalks in the fall (September-November) or in late winter (March) when most weeds aren’t germinating will help reduce weed problems in these areas. Lastly, careful attention during construction and traffic management following establishment will help prevent future problems in these hot spots.

Large crabgrass growing next to a sidewalk

Purslane and yellow nutsedge next to a sidewalk

Prostrate spurge next to a sidewalk

Newly edged sidewalks with exposed soil.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

Aaron Patton, Turf and Weed Science


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