Seeding lawn after application of 30% Vinegar

Asked April 10, 2019, 3:34 PM EDT

I have large patches of grass I believe to be Poa Trivialis and patches of crab grass. I would like to eradicate them using 30% vinegar mixed with orange oil. How soon can I seed those areas with tall fescue? If the vinegar kills these grasses do I need to pull out the dead grass and add compost or just put compost and grass seed over the dead weeds. If you have a better solution, please share it with me. Because of the extensive ground saturation in the fall which delayed aerating the soil, I was not able to seed my lawn until the winter and have not been able to apply a pre-emergent this year. I live in 21212 if that helps. Thanks

Baltimore Maryland lawns and turf weeds

1 Response

Poa trivialis is a perennial grass that is very challenging to control. There are not a lot of options. Glyphosate is considered the best available herbicide to use on it.
https://extension.umd.edu/hgic/topics/roughstalk-bluegrass

If you want to use an alternative to glyphosate, please be aware that products like vinegar/acetic acid and botanical oils are not safer and are not as effective. They will burn down the leafy growth but do not kill the roots of mature perennial plants. High strength acetic acid is very caustic. Refer to this page about alternatives to glyphosate. https://content.ces.ncsu.edu/are-there-alternatives-to-glyphosate-for-weed-control-in-landscapes

Also, here is information on organic lawn care and dealing with weeds. https://extension.umd.edu/hgic/topics/organic-lawn-care

Crabgrass is typically treated with pre-emergent at this time of year to prevent germination of seeds. You can spot-treat crabgrass plants with a post-emergent herbicide. See our website for options and the active ingredients to look for on the product label. https://extension.umd.edu/hgic/topics/crabgrass

You will have to read your herbicide product labels to find out when to apply seed after treatment. Products vary in their concentration and ingredients, so you have to read the labels.

Maintaining dense turf with good practices such as fertilizing (in the fall) based on soil test results, aeration, overseeding, and "mowing high" will help to prevent weeds. Research has shown that mowing higher reduces crabgrass significantly.
https://extension.umd.edu/hgic/topics/mowing-grasscycling-lawns

Here are more tips on managing weeds. https://extension.umd.edu/hgic/topics/lawn-weed-id-and-management

Christa