Hello Linda,

Thank you for contacting the El Paso County Extension office of the CSU LAwn and Garden Help Desk with you question about pine needles effect on your Kentucky Bluegrass. 

I have attached a link to an article about one of the persistent myths that pine needles create acidic soil. The truth is that the shade provided by pine trees and the consequent shileding of the grass from water provided by rain and snow have a far more detrimental effect than any acidity from the needles. 

I recommend three possible solutions to help alleviate the problem. Prune back the branches hanging over your lawn so that the grass gets more sunlight and more water from rain and snow. Rake up the pine needles regularly to allow your soil and grass to breathe. If this fails to alleviate the problem it may be time to modify your lawn under the pine tree with either bark mulch or a shade loving native ground cover. I have included a link to an article which lists several shade loving ground covers which do well in dry soil. 

https://planttalk.colostate.edu/topics/annuals-perennials/1080-drought-tolerant-groundcovers-shade/

https://elpaso.extension.colostate.edu/wp-content/uploads/sites/44/2019/08/August-10-2019-Pine-Needle-Myths.pdf

I am sure these resources and suggestions will help you make a determination as to how to deal with the pine trees about your lawn.

Happy Gardening,

Gary C.

Colorado Master Gardener

Hi Linda,

There is no acidic effect with pine needles.  It is more a physical effect. If the needles are left to accumulate on your lawn they will damage the grass underneath. Similar to using mulch to suppress weeds.  I hope this has cleared up any misunderstandings about pine needles being acidic and damaging your lawn. 

Thank you very much.

Loretta M. 

Colorado Master Gardener