Enthusiastic gardeners can easily become enthusiastic “mulchers,” placing copious amounts of high quality mulch close to and around every plant the gardens. While GardenZeus applauds the effort, we also recommend some caution. Orange trees can be over-mulched or mulched to close to the trunk and major roots.
GardenZeus recommends bare soil only with no plantings and no mulch for a distance of 2 to 4 times the diameter of a citrus tree’s trunk, and at least several inches to a foot or more from major root buttresses and surface roots. This helps to avoid trapping moisture near trunks and major roots, which may encourage pathogens.
Outside of the area near the trunk and major roots, citrus trees benefit from a year-round layer of mulch to retain moisture, inhibit weeds, feed the soil, moderate soil temperature, and protect shallow feeder roots. Young and establishing trees can be mulched with 1-to-2.5-inch layer of medium to coarse mulch such as wood chips, leaves, straw, or pine needles.
Be cautious with adding a thick layer of mulch around an established tree. Mulch may reduce critical oxygen exchange to feeder roots, and cause stress to a tree; in a few rare instances while consulting as an arborist, GardenZeus expert Darren Butler has seen mature trees apparently killed by overly enthusiastic mulching. For established citrus trees that might not have been previously mulched, start with a shallow layer of about 1/2 inch coarse mulch well away from the trunk and main roots, and allow a period of weeks to months for the tree to adjust before progressively adding thicker mulch.
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