privet root system
Cheyenne privets line our backyard deck. As we replace the old deck, we plan to install a rabbit/rodent barrier between the privets and the deck. That will entail digging a small trench (18" to 24" deep) next to the privets. How much space from the trunk of each privet should we place the trench such that the root system is not hurt? This same question was addressed to my home County Extension in Jefferson County, but I received no reply. Would you be willing to help me, please?
Arapahoe County Colorado
Sorry you did not get a quicker response to your original question.
In general, you want to try to protect as much of your shrubs roots as possible. Most shrubs can lose up to 25% of their roots and easily survive. The tricky thing is, how far out are your privets roots extending beyond their trunk? You may need to do some exploratory shallow digging to determine this. The roots will no doubt extend beyond the drip zone. Once you have determined that, you can make your plan.
Here are a couple of links which may be helpful in reducing the negative impact your project will have on your plants.
Protecting trees and shrubs from construction damage https://cals.arizona.edu/yavapai/anr/hort/byg/archive/constructiondamage2016.html
protecting trees from construction damage (I know your privets are shrubs, but the information contained here may be helpful.) http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/protecting-trees-from-construction-damage/
this was not helpful. I asked the CSU Extension how far from the trunk privet roots normally extend. Instead of stating that the Extension has no information, you told me to do the research myself by exposing the root system. You also told me the plant could be damaged if we cut too closely. That piece of information merely restates the reason I stated for making the inquiry in the first place.
Wouldn't it be more effective and efficient to locate someone who knows what a privet's root system looks like? Does this plant send down deep roots or does it spread? Does the height of the shrub make a big difference in where the roots are located? Would most of the root system be found one foot from the trunk? Two feet? Three feet?
I have referred your question to another individual. I hope they will be of more help.
Tree and shrub roots will extend 3-5 times the height of the plant in question. All of the absorbing roots are in the top 6-12 inches of soil. The variability in length and width of the root system depends on your soil type and how the plant is watered. That being said, If you cut your trench at the drip line I foresee no major damage to the privets. Any closer and damage may occur. The good news is privets have a very fibrous root system and will regrow severed roots quickly next spring IF you provide sufficient water to the trench weekly for the next year.