Cedar trees grow naturally in many parts of the country and have specific soil needs to grow. These towering evergreens make impressive additions to your yard and landscape. In some cases, little else grows beneath the towering canopies as the falling leaves can affect the pH of soil under cedar trees. Learning about the different soil requirements for the different cedar trees can help you decide what to plant beneath the trees.
Types of Cedar Trees
There are several varieties of cedar trees. Some prefer acidic soils and some prefer alkaline soils. The Cedrus atlantica, "atlas cedar," is an evergreen that grows at a slow to average rate in acidic, well-draining soils.
The Cedrus libani, "cedar of Lebanon," is a cold, hardy evergreen tree that produces needles in dry, alkaline soil. The Cedrus deodara, "deodar cedar," is a needled evergreen that grows well in acidic or alkaline soils that drain well. The Juniperus virginiana, "Eastern red cedar," is a needled evergreen that can thrive in an alkaline or acidic soil.
The Thuja occidentalis, "Northern white cedar," is an evergreen that needs moist alkaline soils to flourish. The Thuja plicata, "Western red cedar," evergreen enjoys a lightly acidic to alkaline soil to grow.
What Is Soil pH?
The pH of soil measures the level of hydrogen in the soil. When hydrogen leaves the soil, the soil becomes acidic; conversely, when more hydrogen enters the soil, it becomes alkaline, or basic.
A scale from 0 to 14 determines the pH, with a pH of 7 at the neutral median point; anything below is acidic and above the median is alkaline. The average pH for cedar trees ranges from 6.0 to 7.5.
Eastern red cedars, for example, often grow in alkaline soils, but will also establish in acidic soils as well. There, they tend to neutralize and aerate the soil. The needles provide the soil with more calcium, making it more favorable to earthworms.
Plants Compatible With Cedars
Plants with similar soil and nutrient requirements can thrive beneath cedar trees. While many plants will not grow in the acidic soil beneath cedar trees, plants such as blueberries and rhododendrons tend to thrive there.
Hostas have the same soil requirements as some cedar trees, that being slightly acidic to slightly alkaline, with a soil pH of 6.5 to 7.5. Make sure you water your hostas regularly to get them established.
To grow grass beneath cedar trees, sprinkle lime to raise the pH or sulfur to lower the pH beneath cedar trees. Plant shade tolerant grass seed, because the area is likely not to get much sun.
Cedar Soil Considerations
The foliage of the Eastern red cedar contains amounts of calcium that can neutralize the pH of the soil beneath the trees, which may help the growth of some plants beneath the tree.
If you want to plant beneath your cedar tree, you can adjust the pH level in soils by adding compost, lime or sulfur. Have the pH in the soil tested before you take steps to amend the level.
After attending the University of Missouri St. Louis, Stephanie Rempe worked as a documentation manager in the finance industry 10 years before turning to her first love, writing, which she's been doing professionally since 2008. She currently divides her time between Missouri and her fiance's hometown in Oregon. In addition to her freelance writing, Rempe is working on a romance novel and short stories.