More than 50 species belong to the Juniperus genus, commonly known as juniper. Depending on the species, junipers thrives in all of the United State Department of Agriculture plant hardiness zones of 1 through 13. While junipers provide benefits such as beauty in the landscape, ground-covering shrubs on banks and berries that attract birds and can be used in culinary dishes, many junipers are invasive in various areas. Making mulch with juniper wood lets you revitalize and protect other plants while removing or curbing junipers that compete a little too well with others in the landscape.
Juniper's Biochemical Arsenal
Allelopathy is a natural occurrence in the plant world where some plants emit biochemicals to limit competition by stunting or stopping the growth of competing plants. Testing shows that fresh juniper mulch has a mild allelopathic effect on the germination of many garden seeds, but little to no effect when used around sprouts and established plants, according to the Oklahoma Biological Survey, a state office and research unit of the University of Oklahoma. And juniper mulch may interfere with the chlorophyll production of common turf grasses. Play it safe by not using juniper-based mulch on the lawn or germinating seeds. But do consider using it as a mulch on sprouts and established plants.
Chipping Away One Branch at a Time
Renting a wood chipper and shredder will help you turn branches into mulch, but anything over a few inches in diameter requires large equipment and professionals to operate it. If you choose to use a rented chipper, be sure to keep children and pets out of the work area. The New Jersey Landscape Contractors Association also recommends clearing the pile of mulch coming out of the chute regularly to avoid clogging and the use of a wooden pole, rather than your hands, to push material into the feed chute.
Maybe its Cedar -- Maybe its Juniper
Juniper mulch provides a lovely scent and its reddish brown chips look great when spread along pathways. If you have ever admired "red cedar" mulch, you may have been really admiring a mulch made of the juniper commonly called eastern red cedar (Juniperus virginiana). A layer of mulch made from juniper, a hardwood, will keep the soil cool and moist by slowing down evaporation. It may also help repel insects due to the essential oils within the wood, according to the Lady Bird Johnson Wildflower Center.
Gardeners using any kind of wood mulch, including chips or shreds of juniper, need to consider the threat of nitrogen depletion. As the wood breaks down and decomposes, it pulls nitrogen from the soil. This can lead to nutrient deficiencies in the plants sharing that soil. Supplemental application of a fertilizer rich in nitrogen can offset this problem. The Oregon State University Extension Service recommends adding 3 to 4 pounds of a pure nitrogen fertilizer product per cubic yard of mulch to ensure that while the mulch breaks down it doesn't create a deficiency in the soil. Work the fertilizer into the soil before spreading the mulch. Use gloves, and follow the product labels directions and warnings.
- Oklahoma Biological Survey: Battle of the Space Invaders - A Study of the Allelopathic Properties of Garden Mulches
- Lady Bird Johnson Wildflower Center: Should Shredded Ashe Juniper Be Composted For Mulch?
- New Jersey Landscape Contractors Association: 5 Essential Wood Chipper Safety Tips
- Oregon State University Extension Service: Understanding Nitrogen Fertilizers
- Photo Credit Brand X Pictures/Brand X Pictures/Getty Images