How to Grow Cedars in Acidic Soil
There are many types of cedar trees that grow well in a variety of soil conditions in U.S. Department of Agriculture plant hardiness zones 3 through 10, depending on the species. Most cedars prefer an acidic soil, with some growing best in alkaline soil. White cedar (Thuja occidentalis) grows in a pH range from 5.5 to 7.2. Red cedar (Juniperus virginiana) needs a more neutral pH between 6.8 and 7.2. Blue Cedar (Juniperus virginiana "Manhattan Blue") grows in either highly alkaline or highly acidic soil. If the pH of the soil is right for the cedar that you want to grow, nothing needs to be done. Otherwise, adjust the soil pH to a level that will work for your tree.
Test the soil pH with a test kit according to the manufacturer instructions to determine the pH of the planting site. If the pH test results fall within the acceptable range for your tree, nothing needs to be done to the soil. If the pH is too low or too high, you can add amendments to adjust the levels.
Spread lime over the planting area to raise a pH that is too acidic. The amount of lime needed will depend on the current pH and the level you need to attain. Follow the instructions on the package for rates. Spread the lime over the planting area and till or dig it into the soil. Water it in to spread the amendment deeper into the soil. Depending on the type of lime you use, the change in pH can take up to a year.
Spread sulfur or iron sulfate over the planting area to lower the pH if the soil is too alkaline. Sulfur is a slow-acting soil acidifier, while iron sulfate works in a few weeks. Spread the amendment over the planting area according to the manufacturer's instructed rates. Dig or till the amendment into at least the top 6 inches of soil, and water it in.
- Soil pH test kit
- Amend soil before planting. Do not add amendments to the planting hole, they can burn the tree roots.
- Amendments can be spread around existing trees and watered into the soil at lower rates if the tree is showing signs of stress from improper pH levels. Brown or yellowed foliage can indicate pH stress.
- University of Minnesota Department of Horticultural Science: Modifying Soil pH
- North Dakota State University Cooperative Extension: American Arborvitae
- Floridata: Juniperus Virginiana
- Northeastern Area State and Private Forestry: Northern White-Cedar
- The University of Texas at Austin Lady Bird Johnson Wildflower Center: Juniperus Virginiana
- Cal Poly Urban Forest Ecosystems Institute: Manhattan Blue Cedar
- Comstock/Comstock/Getty Images