Every autumn I rake up a mountain of needles. For years they went to the green waste bin, because "pine needles make the soil too acidic". Last November I decided to test that and used them as mulch on two vegetable beds instead.
The setup
Two beds, same soil, same compost. One got about 5 cm of fresh needles, the other was left bare over winter. I measured pH with a cheap kit in November and again in May, three samples per bed.
The numbers
- Mulched bed: 6.4 in November, 6.3 in May.
- Bare bed: 6.5 in November, 6.4 in May.
In other words: no real difference. Fresh needles are acidic, but by the time they break down they are close to neutral, and a thin layer on top barely touches the soil below. This matches what most extension services say, so I am not surprised, just glad to see it in my own garden.
What I did notice
- The mulched bed stayed noticeably moister in April.
- Fewer weeds, although a few pine seedlings appeared.
- Needles do not blow away the way straw does — they knit together.
- Slugs seem to dislike crawling over them. Not scientific, but the lettuce agrees.
Conclusion for now: the needles stay in the garden. I will keep the bin for the cones.