Can pine needles be used as mulch around nine bark shrubs to reduce weeds?
Question:
I have several nine bark shrubs planted beneath large pine trees. I usually rake up the pine needles around them in the fall, leaving compacted dirt. The dirt produces weeds throughout the summer. I was wondering if it would be okay to leave the pine needles as mulch around them, thus inhibiting weed growth. Would this cause any negative effect on the nine bark shrubs?
Answer:
Ninebark (PHYSOCARPUS opulifolius) is a very hardy native shrub and generally doesn’t need much TLC. The compacted exposed soil is really the question here. Leaving the pine needles and other leaves in that area is actually a recommended strategy. The October issue of the Maine Home Garden News actually talks about “leaving the leaves” in non-lawn areas of the garden. (click on the underlined blue text to go to the resource).
The other thing to consider, in the long term, is how shady that spot will become. Ninebark likes full sun but obviously survives in less-than-ideal conditions. Survival is one thing, thriving is another and a stressed tree is more susceptible to disease and pressure pressure. Consider “limbing up” those pines periodically to provide better air circulation and more light on those native foundational species.