Cypress knees can be removed by cutting or grinding them down to ground level, but they frequently regrow because they are living woody projections of the tree’s root system, not separate growths you can simply pull out. Removing them is straightforward labor; keeping them gone is the harder problem. Understanding why baldcypress trees produce knees in the first place makes the difference between a one-time fix and an annual chore.
Why Baldcypress Trees Produce Knees
Cypress knees are vertical extensions that grow upward from the lateral roots of baldcypress (Taxodium distichum) and, less commonly, pondcypress. They are not roots growing in the wrong direction. They are woody, cone-shaped or dome-shaped protrusions that can range from a few inches to several feet tall, and they are made of the same wood and bark as the rest of the tree. Their outer bark is distinctively porous, composed largely of fibers and thin-walled cells that flake off easily, leaving only a few layers clinging to the inner bark beneath.
For over a century, botanists debated whether knees actually serve a purpose. The leading theory was that they function as pneumatophores, structures that channel oxygen down to roots sitting in waterlogged, oxygen-poor soil. Research has confirmed this: when roots are submerged, the oxygen concentration inside the root is substantially higher when the knee remains above the waterline than when both the knee and root are underwater.1International Journal of Plant Sciences. Root Aeration Function of Baldcypress Knees (Taxodium distichum) In other words, knees act like snorkels. That porous outer bark is part of the system, allowing gas exchange between the atmosphere and the knee’s internal tissues.2Flora. Bald Cypress knees, Taxodium distichum (Cupressaceae): An anatomical study, with functional implications
This matters for anyone trying to remove knees because it means they are not decorative or accidental. They are a functional part of the tree’s survival toolkit. In a yard where the soil stays relatively dry, the tree may not need its knees as desperately as it would in a swamp, but the tree does not know that. It produces knees based on root conditions and seasonal flooding cues, not based on whether you find them convenient.
What Triggers Knee Growth
A 14-year field study tracked individual cypress knees and found that meaningful growth happens only during a specific window: the months of June through September, and only when floodwater levels rise above the ground surface during that period. No flooding during summer, no significant knee growth. The study documented years like 2012 and 2023, when dry summers produced essentially no knee expansion, and unusual winter flooding in 2016 and 2024 that also failed to trigger growth because the tree was dormant.3PubMed Central. Cypress (Taxodium) Knee Seasonal Growth Is Stimulated by Flood Water Levels and Constrained by the Tree Dormant Season: A 14-Year Study
Higher water levels and longer periods of flooding during summer correlated with both taller knee growth and a greater proportion of knees actively growing that season. The study also noted that about 90 percent of knee tips were already above the average high-water mark at the start of the monitoring period, suggesting that once a knee clears the typical waterline, it slows down. The advantage of growing during floods appears to go beyond just gaining height: submerging the thin-barked growing tip in water may boost gas exchange that fuels starch storage and nutrient transport inside the knee.3PubMed Central. Cypress (Taxodium) Knee Seasonal Growth Is Stimulated by Flood Water Levels and Constrained by the Tree Dormant Season: A 14-Year Study
For homeowners, the practical takeaway is that knees grow most aggressively in landscapes where soil stays saturated or floods during the warm months. A baldcypress planted in a well-drained suburban lawn will still produce knees, but they tend to be smaller and slower-growing than those on a tree near a pond, creek, or low-lying area that collects rainwater.
Cutting and Grinding Knees at Ground Level
The most common removal method is cutting each knee flush with the surrounding soil. You can use a handsaw, reciprocating saw, or chainsaw depending on the size of the knee and how many you are dealing with. For large knees or dense clusters, some people use a stump grinder to take them below grade. A few things to keep in mind:
- Cut flush, not deep: You want the cut at or just below the soil surface. Digging down and cutting into the root itself increases the risk of opening a wound that invites fungal infection into the root system.
- Timing matters less than you’d think: Because knees grow mainly during summer flooding, cutting in late fall or winter is slightly preferable since the tree is dormant and sap flow is minimal. But knees can be cut any time of year without killing the tree.
- Sharper tools, cleaner cuts: A ragged tear heals more slowly and is more vulnerable to pathogens than a clean saw cut. Dull chainsaw chains tend to rip the soft, fibrous bark rather than slicing through it.
- Watch for hidden knees: In lawns where soil or mulch has accumulated, small knees may be buried just below the surface. Probing with a metal rod or carefully raking back soil near the root zone can reveal them before your mower finds them the hard way.
Cutting knees will not kill a baldcypress. The knee is an outgrowth of a lateral root, and severing it at ground level is comparable to a superficial wound on a major root. The tree will compartmentalize the wound over time. Removing dozens of large knees at once from a single tree is more stressful than trimming a few, so if you are dealing with a major cluster, spreading the work over two or three seasons is gentler on the tree.
Will They Grow Back
Usually, yes. Cut knees frequently regenerate from the same spot, especially if the conditions that triggered their growth in the first place have not changed. The root beneath the knee is still alive and still capable of producing upward growth. Some homeowners report cutting the same knees every two to three years; others find that certain knees never return after a clean cut. There is no reliable way to predict which outcome you will get.
Regrowth tends to be slower and smaller than the original knee, at least for the first few years. A knee that took a decade to reach 12 inches probably will not bounce back to that height in two seasons. But given enough time and the right moisture conditions, it can get there. This is the central frustration of cypress knee management: the tree is doing exactly what its biology tells it to do, and cutting the symptom does not change the underlying signal.
Managing Soil Moisture to Slow Regrowth
Since knee growth is driven by warm-season flooding, anything you can do to keep the soil around the root zone drier during summer will slow knee production. This is not always practical, and it will never eliminate knees entirely on an established tree, but it can reduce how aggressively they return after cutting.
If the tree sits in a low spot that collects standing water after rain, improving drainage is the single most effective long-term strategy. French drains, regrading, or redirecting downspouts away from the root zone can lower the water table enough to reduce the flooding signal that triggers growth. On properties near ponds or creeks, this may not be feasible, and that is worth acknowledging honestly: if your baldcypress has constant access to standing water during summer, knees are part of the deal.
Raising the grade around the tree by adding soil is a common impulse, but it creates its own problems. Burying the root flare under fill dirt can suffocate the bark, promote root rot, and actually worsen the conditions that encourage knee formation by trapping moisture against the trunk. If you add soil, keep it thin (no more than a couple of inches), use a well-draining mix, and never mound it against the trunk.
Herbicides and Chemical Approaches
You will find advice online suggesting that painting a freshly cut knee stump with a glyphosate-based herbicide or a triclopyr product will prevent regrowth. This is risky and generally not recommended by arborists. The knee is part of the tree’s root system. Any systemic herbicide absorbed through the cut surface can travel through the vascular network into the roots and potentially into the trunk. The tree may not die outright, especially a large, healthy specimen, but you are introducing a toxin directly into its circulatory system. The result can be localized dieback, branch death on one side of the canopy, or general decline that shows up months later.
Some arborists do use targeted growth-regulator chemicals (not herbicides) applied to the soil or trunk to slow overall root vigor, which can indirectly reduce knee production. These products are professional-grade and require careful dosing relative to the tree’s size. They are not a DIY solution. If you are considering chemical intervention, hiring a certified arborist who has experience with baldcypress is the only responsible path.
Mechanical Barriers Below Ground
Another approach involves installing a physical root barrier in the soil to prevent roots from sending knees up into a specific area. This is the same concept used to keep tree roots from cracking foundations or lifting sidewalks. High-density polyethylene barriers buried vertically to a depth of 18 to 24 inches can redirect root growth and block knee emergence in a targeted zone, such as a strip of lawn between the tree and a patio.
Root barriers work best when installed before knees appear in the protected area. Retrofitting them into an area already dense with knees and roots requires trenching through the root zone, which is disruptive and can damage roots you do not want to cut. The barrier also does not prevent knees from appearing everywhere else outside the protected zone. It is a localized solution, useful for keeping a walkway or play area clear rather than eliminating knees across the entire yard.
One caution: cutting off a large section of root access on one side of a tree can affect its stability. Baldcypress trees are famously wind-resistant, partly because of their broad, spreading root systems. Severing roots during barrier installation on one side without compensating root mass on the other side could make the tree more vulnerable to leaning or toppling in storms, particularly in saturated soils.
When Knees Damage Structures and Hardscaping
Cypress knees are remarkably persistent. They can push through thin layers of asphalt, lift pavers, crack shallow concrete slabs, and emerge through landscape fabric. The force involved is not dramatic on any given day, but a knee that grows a fraction of an inch per season can generate serious cumulative pressure over years. Mower damage is the most common complaint, since knees lurking just at or below turf height catch blades and scalp the lawn.
If knees are actively damaging hardscaping, the realistic options are to remove the knees and install a root barrier to prevent recurrence in that specific zone, to reroute the hardscaping around the tree’s root zone, or to accept that the tree and the pavement are incompatible in that location. Repeatedly cutting knees that keep cracking a sidewalk is a losing battle if the root underneath remains vigorous and the drainage conditions keep fueling growth.
Some homeowners face the more difficult question of whether to remove the tree entirely. Baldcypress is a beautiful, long-lived species that provides excellent shade and impressive storm resistance. Removing a mature specimen is a significant loss, both aesthetically and ecologically. But in cases where the tree was planted in a small yard, close to a foundation, or over a septic system, the knees can become a genuine structural liability that trimming alone cannot manage. An arborist can assess whether the root system’s spread and knee production are likely to stay manageable or escalate over the coming decades.
Knees in Natural and Protected Areas
If your baldcypress grows along a wetland, creek, or other waterway, local regulations may restrict what you can do. Many U.S. states protect riparian buffer zones, and some municipalities specifically regulate tree work within wetland setbacks. Baldcypress is a native species in much of the southeastern United States and plays an important ecological role in floodplain forests, including stabilizing banks, filtering runoff, and providing habitat. In some jurisdictions, removing cypress knees near a waterway without a permit can result in fines.
Even where no regulations apply, think twice before aggressively removing knees from a tree in a wet or flood-prone setting. Those knees are actively supplying oxygen to roots that sit in anaerobic muck.1International Journal of Plant Sciences. Root Aeration Function of Baldcypress Knees (Taxodium distichum) Removing all of them could compromise the tree’s ability to survive prolonged flooding. In a well-drained suburban lawn, the stakes are lower because the roots have better access to oxygen through the soil anyway. But in a legitimately wet environment, the knees are doing real work.
Creative Alternatives to Removal
Not everyone who searches for how to get rid of cypress knees has decided they must go. Some people just want the knees to stop being a problem, which is a different goal. A few approaches that sidestep removal entirely:
- Convert the area to a mulch bed: Instead of fighting knees in a mowed lawn, define the root zone as a landscaped bed with several inches of mulch. Knees poking through mulch are not a mowing hazard, and the bed can look intentional with shade-tolerant plantings around the perimeter.
- Install a raised path or boardwalk: In areas where knees cross a foot-traffic route, a simple raised walkway bridges over the knee zone without requiring any cutting. This is common in parks and gardens that feature mature baldcypress.
- Embrace them as a feature: Cypress knees have a distinctive sculptural quality. Some landscape designers incorporate them into garden design rather than fighting them, using ground cover like ferns or moss around the bases. It is an aesthetic choice, but it turns a maintenance headache into a conversation piece.
These options work best when the knees are not actively threatening structures. If they are lifting your driveway, a mulch bed around the base of the tree does not solve the problem. But for knees scattered across a lawn where the main complaint is tripping hazards and mower damage, rethinking the landscape around the tree’s biology is often more sustainable than an annual saw session.
Choosing a Baldcypress Wisely in the First Place
If you do not yet have a baldcypress but are considering planting one, site selection is the best prevention. Trees planted in consistently well-drained soil with no seasonal flooding produce fewer and smaller knees than those planted near water features or in low-lying yards. Knees may still appear, but they tend to be scattered and manageable rather than a dense field.
Planting at least 15 to 20 feet from sidewalks, driveways, foundations, and septic systems gives the root system room to spread without generating conflicts. Baldcypress roots can extend well beyond the canopy, so even generous spacing may not prevent every knee from showing up where you would rather it did not. But it stacks the odds in your favor. There are also cultivated varieties bred for denser canopy form and more compact growth, though no cultivar has been reliably shown to be “kneeless.” The tendency to produce knees appears deeply embedded in the species’ genetics, shaped by millions of years of adaptation to floodplain life. Managing them, rather than eliminating them forever, is the realistic expectation for anyone living with a baldcypress.