Q. Should I leave the pine needles around the basin of the trees, or should I rake them out and pick them up? I feel that cleaning them from under the trees helps the water penetrate into the soil quicker and not sit on top of the needles.  My part-time gardener says I should keep them around the trees so that they act as a mulch.  Which is correct? In the desert, pine needles mixed with other ingredients for compost, add nutrients to the soil.  A. Your gardener is correct but in a reverse sense you are too! If you can stand leaving the pine needles in place, (they do not make the soil more acidic, and if they did, what’s wrong with that?) they will decompose (provided the soil is kept moist) more slowly than fine woodchips. But they will decompose. These decomposing pine needles add to the soil nutrition and soil organic content. If there is enough of them (2-3 inches deep) they conserve soil moisture, add organics to the soil as they rot, keep the soil cooler and help prevent annual weeds. Pine needles make a good compost even if they don’t rot as easily as some other ingredients and, in desert soil where a lack of acidity is a problem, can maybe help to pH lower! A common problem reported has been that they create acidity when they rot. In the desert, who cares? Our soil needs it.             Rake the pine needles so they are 2 -3 inches deep under at least half of the canopy of the pine tree. If the trees are not yet ten years old (or bark has not started to develop on the trunk) then keep them away from the trunk 6 to 12 inches (keep that soil uncovered and dry).