Hi Cheryl,

Thank you contacting UNH Cooperative Extension with your question about using pine needles to mulch your garden. Below is an excerpt from a question and answer UNH Extension blog.

"Pine needles are often readily available and can be an abundant source of free mulch in the home landscape. They are rumored to acidify the soil, but this has been disproven. Like shredded bark, leaves, and wood chips, pine needles can be great as mulch for weed suppression, water retention, and adding rich organic matter to the soil as they decompose.

There is a common misconception that pine needles acidify the soil and should not be used as mulch. Studies have shown that this is false and they have no measurable effect on soil pH when they break down. Instead of bagging and disposing of needles they can be seen as an abundant source of free mulch if you have them in your landscape. As with other commonly used mulches like shredded tree bark, leaves, and wood chips, pine needles can help with moisture retention, weed suppression and moderation of soil temperature. They do not form a dense mat like other mulches which can improve water penetration. Pine needles break down relatively slowly so there is less need for re-application and they are a great source of organic matter for the soil".

I have also included a link to a fact sheet that discusses using pine needles as mulch.

https://extension.unh.edu/blog/2019/10/do-pine-trees-pine-needles-make-soil-more-acidic