Ask a Master Gardener: Can shredded paper be used in mulch?
Like other types of mulch, paper is effective in controlling weeds at depths of 3-4 inches.
Q: I work in an office that produces a lot of shredded paper. Is it safe to use it as a mulch or in a compost pile?
A: First, a word of caution: Be sure that your employer permits removal of the company’s shredded documents. If the answer is yes, shredded paper can be used for mulching and composting, but like other materials used for these purposes, quality and quantity need to be considered.
Today, most inks used for printing are vegetable-based and therefore safe for mulching and composting. To be safe, check the label on the box containing the printer cartridges. Colored and glossy paper tend to contain heavy metals and should not be used.
Like other types of mulch, paper is effective in controlling weeds at depths of 3-4 inches. Paper breaks down over time contributing to the porosity of the soil, retains moisture, and helps maintain consistent soil temperatures in extreme hot or cold conditions. Paper may be covered with straw to keep it in place in dry, windy conditions.
Keep in mind that certain types of paper become slippery when wet and should not be used in areas that get any foot traffic. Because of its insulating properties, spring mulching is most effective when soil temperatures have reached 40-50 degrees depending upon the type of plants, to permit warming and germination.
When using shredded paper in compost bins or piles, balance is the key. Too much paper will adversely affect carbon to nitrogen ratios (ideally 25:1), slowing down the composting process. Using high nitrogen materials such as grass clippings, leaves, or manure will produce a more balanced compost. Remember to use well-chopped materials and frequently turn your compost.
Don’t forget to test your soil to ensure optimal soil conditions for your gardens and flower beds.
More information about mulching, composting and soil nutrients may be found at the following links. Happy growing in the spring!
Written by U of M Extension Master Gardeners in St. Louis County. Send questions to firstname.lastname@example.org .