Pine Cones and needles in the soil.

Asked March 25, 2019, 4:24 PM EDT

I have a moderately steep slope in my front yard that was covered in junipers, that we removed. We also had several pine trees in our front yard. This hill is full of pine needles and pine cones I have attempted to get them out, but there are too many. It appears the pine needles are decomposing the further down I go, but not really the pine cones. I am planning on planting various ground covers. Should I get a load of dirt and cover the soil? Or should I just dig down and put in new soil where I am planting? Also I have wood chips from grounded stumps. Should I use this as cover between plants? Will it prevent my ground cover from spreading?

King County Washington mulch pine needles

1 Response

Thanks for your question. You can certainly jumpstart your groundcovers with a load of topsoil, but the needles, at least, are actually helping to nourish the soil and will, in time, keep it 'loamy' and full of nutrients. Here is a part of an answer to a similar question, by one of our state's Extension agents:

"For those of you that leave the needles there on the ground, they will begin to break down naturally and the microbes (decomposers) in the soil will neutralize them. So, you can leave them there (if you’re not in a wildfire prone area). They are a good mulching material that will keep the moisture in, suppress weeds and eventually add nutrients back to the soil. You can also add them to a compost pile; they will slowly break down over time. If you run them through a shredder they will break down faster. A general rule of thumb is not to add more than 10 percent of pine needles to your compost pile. " (https://extension.oregonstate.edu/news/myth-vs-reality-whats-truth-behind-some-common-gardening-prac...)

Similar benefits accrue if you use the wood chips as mulch around your plants. Here is a WSU Extension article that explains how and why: http://cru.cahe.wsu.edu/CEPublications/FS160E/FS160E.pdf

Hope these are helpful. Good luck!