What can be done with Crabgrass - July 2020
While there is nothing per se that can be done to eradicate the current infestation (other than removal by hand- which can be helpful as A single crabgrass plant can produce thousands of seeds)
Crabgrass seeds can remain viable for years and when the opportunity arises they will germinate and grow.
So what are the conditions that favour crabgrass and are there things that can be done to reduce it for the future,
Basically crabgrass seeds need warmth and light to grow. If the lawn soil is cool and dark crabgrass seeds won’t germinate.
2020 has had a few weeks of very dry hot weather- those weakens the lawn and creates conditions that crabgrass seed like.
So make sure to mow high- 3” mowing height minimum
Keep the lawn growing well so that there is a thick stand of grass- lawns can be thinned out from insects, traffic/compaction, uneven soil surfaces, salt or ice damage, heat and/or drought stress.
So watch for insect damage, watch traffic patterns, level or adjust lawn surfaces, repair salt damaged areas, water deeply in drought conditions.
If the lawn has been thinned our, reseed the lawn to increase density. Fall is the best time to seed lawns.