After a tree is cut down, most of the attention goes to the stump and the debris above ground. But the root system, which can extend far beyond the canopy and deep into the soil, is still down there. Understanding what happens to those roots, how long they take to break down, and whether they cause any problems helps you make better decisions about what to do after a tree is removed.
Do Tree Roots Die When a Tree Is Cut Down?
In most cases, yes. Once a tree is cut down and the connection to the canopy is severed, the roots lose their source of energy. Without photosynthesis producing sugars to feed the root system, the roots will gradually die and begin to decompose.
However, there are important exceptions. Many tree species, particularly those that reproduce aggressively, can send up new sprouts from the root system after the main trunk is removed. Species common in Northern Virginia that are known for this behavior include:
- Tree of heaven (Ailanthus altissima), an invasive species that is extremely aggressive at resprouting
- Black locust, which readily sends up root suckers after removal
- Sweetgum, which can produce sprouts from the root collar
- Elm species
- Certain oak and maple species
If the stump is ground down, the sprouting is usually eliminated because grinding destroys the energy reserves in the root collar. If the stump is left in place and simply allowed to decompose, you are more likely to see persistent sprouting, particularly from aggressive species.
How Long Do Tree Roots Take to Decompose?
Root decomposition timelines vary considerably based on tree species, root size, soil conditions, and moisture levels. As a general guide:
- Fine roots (less than a few millimeters in diameter) decompose within weeks to months
- Medium roots decompose over one to three years
- Large structural roots from mature trees can take five to ten years or more to fully break down
Hardwood species like oak and hickory decompose more slowly than softwoods. Roots in moist, biologically active soil decompose faster than those in compacted or dry soil.
Can Remaining Roots Cause Problems?
For most residential situations, roots left in the ground after a tree is removed do not cause significant problems. They simply decompose over time. However, there are some scenarios where remaining roots are worth thinking about.
Sinking or Settling in the Soil
As large roots decompose, the soil above them can settle or sink slightly. This is usually a minor cosmetic issue in open lawn areas, but it can cause uneven surfaces in garden beds or along the edges of structures. If you notice settling in an area where a large tree was recently removed, filling and leveling the area after the roots have had time to break down is straightforward.
Foundation and Hardscape Concerns
Roots that grew close to a foundation, retaining wall, driveway, or sidewalk do not continue growing after the tree is removed, since they no longer have an energy source. However, as those roots decompose, they can leave voids in the soil that may cause settling near structures. In most cases, this is not a serious structural concern, but it is worth monitoring in the years following a removal.
Plumbing and Drain Lines
Tree roots are well known for finding and infiltrating cracked or imperfectly sealed drain lines and sewer pipes. If a tree with invasive roots was located near your home’s drain lines, the roots that have already entered those pipes do not disappear simply because the tree was removed. They will continue to cause blockage issues until they are mechanically removed or treated. If you have had drainage problems associated with tree roots, removing the tree above ground does not solve the problem below.
Fungal Disease Spread
Some tree diseases, including certain root rot pathogens, can persist in root systems and potentially spread to nearby trees through root contact. If a tree was removed because of a serious root disease, consult a certified arborist about whether any precautions are warranted before planting a new tree in the same location.
Does Stump Grinding Remove the Roots?
Stump grinding removes the stump and the surface root flare down to a few inches below grade. It does not remove the entire root system, which can extend many feet from the stump in all directions and to significant depths. What grinding does is destroy the stump’s ability to sprout and remove the visible above-ground portion cleanly.
The remaining roots below ground will decompose on their own timeline. For most purposes, such as planting grass, laying sod, or general landscaping, ground stumps and the roots below them are not a significant issue.
What If You Want to Replant a Tree in the Same Spot?
You can replant after a tree is removed, but there are a few things to consider.
Wait before replanting: Planting a new tree immediately after removing an old one, particularly if the old tree was diseased, can expose the new tree to pathogens still present in the soil. For trees removed due to disease, waiting a season and consulting an arborist about appropriate species choices is wise.
Account for decomposing roots: Decomposing roots affect soil composition and nutrient availability. As roots break down, they consume nitrogen during the decomposition process, which can affect the establishment of a new planting. Amending the soil before replanting and selecting an appropriate location slightly away from the main root mass of the old tree can help.
Species compatibility: Some trees produce allelopathic compounds, which are natural chemicals that inhibit the growth of other plants in the area. Black walnut is the best-known example in Northern Virginia. Replanting in a location where a black walnut stood may require soil amendment or a longer waiting period before the new planting succeeds.
Frequently Asked Questions
Roots that are no longer connected to a living tree stop growing. They will decompose, which can cause minor soil settling, but they do not continue to exert pressure on structures the way live roots can. If live root pressure was already an issue before removal, the removal stops further damage from that tree.
Stump grinding is the most reliable method. Chemical stump treatments applied to a freshly cut stump can also prevent sprouting by killing the remaining root system. Cutting off new sprouts repeatedly as they emerge will eventually exhaust the root system’s energy reserves, but this can take several growing seasons for aggressive species.
Decomposing roots can attract termites and other wood-boring insects. If the old root system is close to your home or other structures, monitoring for pest activity during the decomposition period is a good idea.
Get Professional Tree Removal in Northern Virginia
ADM Tree Services, LLC serves homeowners and businesses across Northern Virginia. Call (703) 771-8080 or fill out our online contact form to request a free estimate for a tree removal.
