Mulch plays an essential role in helping you maintain a neat and tidy landscape by inhibiting the growth of disorderly weeds in your yard, flower beds and gardens. According to Charlotte Wilcox, author of "Recycling," crushed, recycled rubber in the form of mats or loose pieces works well as a mulching material because it helps maintain adequate moisture levels in soil. Rather than purchasing a pricey rubber mulch ring for your trees or shrubs, invest your money in a less-expensive rubber mulch mat, which you can use to create a custom-sized rubber mulch ring.
Place the end of a tape measure against the base of your tree or shrub trunk, and extend the tape measure straight out from the trunk as far as you want your rubber mulch ring to go. For a freshly planted tree or shrub, allow the tape measure to extend out at least as far as your tree's drip line (the imaginary circle around your tree that matches the circumference of the tree's outermost leaves) to provide the maximum opportunity for your tree to establish its root system.
Write down the measurement and double it. Add the width of the trunk itself to your measurements to determine the minimum width and length you'll need for your rubber mulch mat. For example, if you want your rubber mulch ring to extend 24 inches out from your tree's trunk and the trunk of the tree measures 2 inches wide, purchase a rubber mulch mat that measures at least 50 inches by 50 inches.
Purchase your rubber mulch mat from a garden or lawn supply center, selecting a color that works well with your current landscaping design. Measure the circumference of the tree trunk, including any exposed roots in your measurements to avoid covering them with the rubber. Lay the rubber mulch mat flat on the ground, and use a permanent marker to make a circle in the center that matches the circumference of the tree trunk.
Cut a straight line from one corner of the mulch mat to the center circle with a pair of utility shears. Slice out the marked circle with the utility shears, cutting slowly to ensure that your hands don't slip. Open the rubber mulch mat and wrap it around the base of your tree, fitting it into place on the ground by bringing the cut edges together. Trim the corners from the rubber mulch mat to create a circular rubber mulch ring.