By Stone Ridge Landscaping LLC — Emmaus, PA | May 2026
The Lehigh Valley — comprising Lehigh and Northampton Counties and the cities of Allentown, Bethlehem, and Easton along with their surrounding townships and boroughs — sits at one of Pennsylvania’s most active intersections of urban forestry pressure, invasive pest spread, and shifting climate. Both counties are inside the statewide spotted lanternfly quarantine, both fall within USDA Hardiness Zone 7a (upgraded from 6b in the November 2023 map revision), and all three cities operate active Shade Tree Commissions that require permits before nearly any work on a street tree. This guide consolidates the local rules, biology, hazards, timing, and resources you need to prune, remove, or replant trees responsibly in the Valley.
1. Tree Species Common to the Lehigh Valley and Their Trimming Quirks
The Lehigh Valley sits in a mixed Appalachian-Piedmont transition zone. Knowing which species you have is the single most important step before deciding when, how, or whether to prune.
Native Canopy Hardwoods
Oaks (white oak, red oak, black oak, pin oak, scarlet oak, swamp white oak)
Oaks are the iconic trees of the Valley’s older neighborhoods — Allentown’s West End, Bethlehem’s North Side, Easton’s College Hill. Critical rule: never prune during the growing season (April through October) because of oak wilt risk. Red-oak-group species (red, black, pin, scarlet — bristle-tipped leaves) are far more vulnerable than white-oak-group species (white, swamp white — rounded lobes). Avoid removing more than 15 to 20% of canopy in mature oaks.
Sugar maple (Acer saccharum)
Best pruned mid-summer (July–early August) or late dormancy. Avoid early-spring pruning when sap flow is heavy — cuts bleed copiously (not harmful to the tree, but alarming). Sugar maples are heat- and salt-sensitive.
Red maple (Acer rubrum)
The most adaptable native maple, very common throughout the Valley. Same bleeding-sap caution; prune in summer or late winter. Develops weak co-dominant leaders — early structural pruning is essential.
Silver maple (Acer saccharinum)
Extremely common in mid-century neighborhoods (Allentown South Side, older Bethlehem). Fast-growing, brittle, prone to storm failure, large surface roots that lift sidewalks. Frequent crown reduction and deadwood pruning is essential. Silver maples are the Valley’s number-one emergency call after windstorms.
Green ash and white ash (Fraxinus spp.)
Treat any untreated ash in the Lehigh Valley as a hazard. Emerald ash borer is confirmed in every Pennsylvania county and most untreated ash are dead, dying, or will be.
Black walnut (Juglans nigra)
Prune only in late summer (August). Like maple, walnuts bleed heavily in spring. The juglone in roots, leaves, and hulls is toxic to many neighboring plants.
Tulip poplar (Liriodendron tulipifera)
Brittle wood, susceptible to summer storm damage. Prune in late winter. Never top — tulip poplars don’t respond well to aggressive heading.
American beech (Fagus grandifolia)
Increasingly threatened by Beech Leaf Disease, now confirmed in all 67 PA counties. Prune only in dormant season; never paint wounds. Avoid root-zone compaction.
American sycamore / London planetree
London planetree is the dominant large street tree in downtown Allentown, Bethlehem, and Easton. Tolerates heavy crown reduction better than almost any other tree. Prune in dormant season.
Landscape and Ornamental Species
Bradford/Callery pear (Pyrus calleryana) — Added to Pennsylvania’s Noxious Weed list in 2024; sale and cultivation prohibited. Structurally weak with brittle branch unions. If you have one, plan for removal — not just pruning.
Norway maple (Acer platanoides) — Invasive in PA. Shallow, dense root systems prevent natives from establishing beneath. Consider removal in favor of native red or sugar maple.
Crabapple (Malus spp.) — Prune in late winter before bud break. Remove water sprouts ruthlessly. Susceptible to apple scab, cedar-apple rust, and fire blight.
Colorado blue spruce / Norway spruce — Prune in late winter, only into living tissue. Valley blue spruces are increasingly afflicted with needlecast and Cytospora canker.
2. Local Pests and Diseases That Drive Trimming Timing
Spotted Lanternfly (Lycorma delicatula)
The Lehigh Valley sits at the epicenter of this invasion. Both Lehigh and Northampton Counties have been inside the Pennsylvania Department of Agriculture quarantine zone for years. What this means for tree work:
- Movement of yard waste, brush, firewood, logs, and outdoor articles is regulated. Businesses moving any of these in or out of the quarantine zone need a PDA-issued SLF permit.
- Inspect everything that leaves your property — vehicles, equipment, mulch, logs — for nymphs, adults, and egg masses (gray, putty-like 1-inch smears on bark).
- Tree-of-heaven is SLF’s preferred host and is itself an invasive. Use the “trap tree” strategy: kill most female tree-of-heaven with herbicide first, then cut. Never simply cut tree-of-heaven down — it resprouts aggressively from roots.
Report SLF to Penn State Extension at 1-888-4BAD-FLY (1-888-422-3359).
Emerald Ash Borer (Agrilus planipennis)
EAB has been confirmed in every Pennsylvania county and has functionally wiped out untreated ash. Signs of infestation: D-shaped exit holes (1/8 inch), S-shaped serpentine galleries under bark, crown dieback from top down, woodpecker “flecking” where bark is chipped away.
- Treatment is only viable while the tree has less than 30% canopy dieback. Systemic emamectin benzoate trunk injection, repeated every 2 to 3 years by a licensed applicator, is the gold standard.
- Untreated dying ash become extraordinarily brittle and dangerous. Many services charge a premium for dead-ash removal because climbing them is unsafe — bucket trucks or cranes are usually required. Remove before the canopy fails.
- Never move ash firewood beyond your own property.
Oak Wilt (Bretziella fagacearum)
Oak wilt is the single most important reason to mark your calendar before pruning oaks. The fungus is spread by sap-feeding beetles that arrive at fresh oak wounds sometimes within 15 to 20 minutes of a cut. Red-oak-group trees can die in weeks once infected.
Pennsylvania pruning window for oaks: prune only December through March. If an oak is wounded outside that window (storm damage, accidental cut): immediately seal the wound with latex paint or commercial tree-wound dressing. This is the only situation in modern arboriculture where wound paint is recommended.
Beech Leaf Disease (Litylenchus crenatae mccannii)
This nematode-caused disease is now confirmed in all 67 Pennsylvania counties. Symptoms: dark banded striping between leaf veins, then leaf curling, thickening, and shriveling. Buds fail to form, canopies thin. There is no cure. Pruning beech in dormant season is fine; sanitize tools between trees as a precaution.
Hemlock Woolly Adelgid
Eastern hemlock — Pennsylvania’s state tree — is severely threatened. White cottony tufts at the base of hemlock needles are the diagnostic sign. Treat established hemlocks systemically (imidacloprid soil drench or trunk injection) every 3 to 5 years.
Anthracnose
Annual issue in cool, wet Lehigh Valley springs, especially on sycamore/London planetree, dogwood, and ash. Causes leaf spotting and twig dieback. Rarely fatal to mature trees. Never treat with cosmetic pruning during the growing season — wait for dormancy and improve air flow through judicious thinning cuts.
3. Pennsylvania State Law and Local Ordinances
City of Allentown — Article 911
- A permit is required for any work on a public-property tree, including the strip between curb and sidewalk
- Only ISA-certified, City-licensed contractors on Allentown’s official annual list may perform paid work on public-property trees
- Permit processing: approximately 10 working days; permits expire 60 days from issue
- Removals require 2-for-1 replacement within 6 months, or fee in lieu
- All work must conform to ANSI A300 standards
City of Bethlehem — Article 910
- Administered by the Bureau of Urban Forestry and City Forester
- Bethlehem is a designated Tree City USA
- No one may do any arboricultural work on a public-property tree without a permit
- Work must be performed by an arborist on the Licensed City Arborists list
- City Hall: 10 East Church Street, Bethlehem, PA 18018, (610) 865-7000
City of Easton — Chapter 554
- A permit is required before any work on any tree in the public right-of-way
- All trees in the right-of-way are the responsibility of the abutting property owner, but the City retains regulatory control
- City Forester: (610) 250-6734
Surrounding Municipalities
South Whitehall Township, Palmer Township, Wilson Borough, and most other Lehigh Valley townships and boroughs have their own Shade Tree Commissions or designated arborist authorities. Always check with your township office before doing right-of-way work.
General Principles
- A tree on your own private property, away from the right-of-way, is generally yours to manage without a municipal permit
- The right-of-way often extends several feet beyond the sidewalk into your lawn — when in doubt, confirm with your city engineer’s office
- Trees overhanging a public sidewalk must be pruned to maintain pedestrian clearance (commonly 8 feet) and roadway clearance (commonly 14 feet)
- HOA covenants in newer developments (Hanover Township, Upper Macungie, Lower Macungie, Forks, Bethlehem Township) may require pre-approval for removal of trees over a certain diameter
4. PPL Electric Utilities Vegetation Management
PPL Electric Utilities serves nearly all of the Lehigh Valley and maintains roughly 33,000 miles of overhead power lines statewide.
- PPL trims pole-to-pole wires. They generally do not trim the service drop running from the pole to your house — that is the homeowner’s responsibility.
- For work near the service drop, PPL will temporarily de-energize and lower the line so you or your contractor can work safely. Call 1-800-342-5775 at least 5 business days before the work.
- For routine pole-to-pole tree issues, call 1-800-342-5775. Have your 10-digit pole number ready if possible.
- Do not attempt to trim trees within 10 feet of a power line yourself. Only qualified line-clearance tree trimmers are legally and practically equipped to do this work.
Right Tree, Right Place: PPL recommends planting trees that will mature over 25 feet tall at least 50 feet from overhead lines. Recommended small-stature trees near lines include dogwood, eastern redbud, American witch-hazel, mountain laurel, black huckleberry, and serviceberry.
5. Seasonal Trimming Calendar for the Lehigh Valley
The Lehigh Valley moved from USDA Hardiness Zone 6b to Zone 7a in the November 2023 USDA Plant Hardiness Map update. Spring bud-break and bloom now arrive 7 to 10 days earlier than 30 years ago — your pruning calendar should shift accordingly. The traditional “late February through mid-March” dormant-pruning window is now best executed in late January through early March for most species.
| Window | Best Uses |
|---|---|
| Late January – early March (dormant) | Most deciduous trees; structural pruning; large reduction cuts; oak pruning safe |
| April | Last safe window for oak pruning — close it by April 1 to be conservative |
| May (after bloom) | Spring-flowering trees: dogwood, redbud, serviceberry, crabapple, magnolia |
| June–early July | Light conifer pruning; Japanese maple thinning |
| Mid-July – August | Summer pruning to slow vigorous growth; walnut and maple safe from sap bleed; tree-of-heaven herbicide treatment |
| September – October | Light cleanup only; avoid major cuts; oak pruning still risky in October |
| November – December | Dormant pruning resumes; elm pruning safe; dead-wooding any species |
Storm Seasons in the Lehigh Valley
- Nor’easters (October–April) — heavy wet snow and freezing rain; leading cause of major tree failure. Wet snow on still-leafed trees in October is especially destructive.
- Summer thunderstorms with microbursts (June–August) — downbursts regularly take down silver maples, Bradford pears, and ash
- Remnants of tropical systems (August–September) — the Valley has been hit hard by Ivan (2004), Lee (2011), Sandy (2012), Ida (2021), and Debby (2024)
- Ice storms (every few winters) — devastating for heavy-crowned, weak-wooded species
6. Hiring a Tree Service in the Lehigh Valley
Credentials That Matter
- ISA Certified Arborist: The single most important credential. Verify at treesaregood.org.
- Pennsylvania business registration, commercial general liability insurance ($1M minimum), and workers’ compensation coverage. Always ask for current certificates of insurance directly from the insurer — not a printed copy from the contractor.
- For pesticide/herbicide work (EAB injections, tree-of-heaven herbicide), the applicator must hold a PA Department of Agriculture pesticide applicator license.
Questions to Ask Before Hiring
- Are you ISA Certified? May I see your certificate?
- Are you on the City of Allentown / Bethlehem / Easton licensed contractor list?
- Will you provide a certificate of insurance directly from your insurer (general liability + workers’ comp)?
- Do you follow ANSI A300 pruning standards?
- Will the work be a thinning or reduction cut, not topping or lion-tailing?
- Will you remove more than 25% of the live canopy? (The answer should usually be no.)
- Who is responsible for cleanup and stump grinding, and is it included?
- Do you have a written contract and what is the cancellation policy?
- Can you provide three local references?
Red Flags — Especially After Storms
- Door-to-door solicitations within 48 hours of a major storm. Legitimate Lehigh Valley services are typically booked solid after storms and do not canvass neighborhoods.
- Demanding full payment up front or cash only
- No local address, only a cell phone, and out-of-state plates on equipment
- Recommends topping the tree — ANSI A300 prohibits topping on most species
- No insurance documentation available or “the office will mail it later”
- High-pressure sales tactics (“we can do it today for cash, today only”)
7. DIY Tree Trimming Guidelines
What Is Reasonable to DIY
- Branches under 2 inches in diameter that you can reach from the ground with hand pruners, loppers, or a pole pruner
- Suckers and water sprouts at the base of the trunk
- Light deadwood and small interfering limbs on young trees you planted yourself
When to Call a Professional
- Anything requiring a chainsaw above shoulder height
- Anything requiring a ladder that places the cutting tool above your waist
- Any work within 10 feet of a power line
- Any tree over 25 feet tall
- Large limbs over 4 inches diameter even on small trees
- Storm-damaged trees with hung-up widow-maker limbs
Tree Biology Rules (Non-Negotiable)
- Always cut just outside the branch collar — the slightly swollen ring where a branch joins the trunk. The collar contains cells that compartmentalize and seal the wound.
- Never make a flush cut (right against the trunk) — it removes the collar and creates a wound the tree cannot seal.
- Never leave a stub — stubs decay back into the trunk.
- Never top a tree — it destroys natural form, invites decay, creates weak water-sprout regrowth, and shortens the tree’s life.
- The 1/3 rule: Never remove more than one-third of a tree’s living canopy in a single growing season. For mature trees, 15 to 20% is a better maximum.
The Three-Cut Method for Larger Limbs
For any limb larger than 1.5 inches, use three cuts to prevent bark tearing:
- Undercut: 6 to 12 inches out from the trunk, cut upward from below about one-third of the way through
- Relief cut: A few inches beyond the first cut, cut downward all the way through — the branch falls; the tear stops at the undercut
- Final cut: Cut the remaining stub just outside the branch collar at the proper angle
8. Storm Preparation and Post-Storm Response
Common Lehigh Valley Storm Damage Patterns
- Silver maples dropping co-dominant leader splits in summer thunderstorms
- Bradford/Callery pears completely splitting in any moderate wind
- Dead ash trees falling at any provocation
- White pines uprooting in saturated soil after multi-day rain events
- Weak V-shaped forks with included bark splitting under ice or snow loading
Preemptive Trimming Before Storm Season
Schedule in late winter (late January through March) for most species:
- Deadwood removal on all mature trees
- End-weight reduction on long horizontal limbs
- Crown thinning to reduce wind sail on dense species
- Removal of any tree where the risk profile exceeds the tree’s value
After a Storm — Protocol
- Stay away from any downed wire. Assume it is live. Call 911 and PPL at 1-800-342-5775.
- Don’t go near hanging widow-maker limbs — they can fall hours or days later.
- Photograph damage immediately before any cleanup.
- Call your insurance company to open a claim if a tree hit a structure.
- Call Stone Ridge Landscaping at (610) 253-5311 for emergency response.
9. Disposal of Tree Debris in the Lehigh Valley
Spotted Lanternfly Quarantine
Do not move logs, brush, mulch, or firewood outside the quarantine zone without inspection. Inspect all materials for egg masses before moving. Businesses moving regulated articles need a PDA SLF compliance permit.
Firewood — Never Move It
EAB and other invasive pests are spread by firewood movement. Buy local, burn local. Don’t bring firewood from one county to another.
Municipal Yard Waste
- City of Allentown: Seasonal yard-waste collection and a year-round compost facility. Branches must be bundled (4-foot maximum lengths, tied) for curbside.
- City of Bethlehem: Seasonal yard-waste pickup with similar bundling restrictions.
- City of Easton: Seasonal yard-waste collection through Public Works.
- Townships: Most contract with haulers for periodic brush collection or direct residents to county composting facilities. Check your township website.
10. Tree Planting Recommendations for the Lehigh Valley
Native Replacements for Dead Ash
The Valley has lost so many ash trees that whole streets need replanting. Avoid monocultures. Strong native large-tree replacements:
- Bur oak (Quercus macrocarpa) — tough, adaptable, white-oak group
- Black gum (Nyssa sylvatica) — brilliant fall color, pest-resistant
- Hackberry (Celtis occidentalis) — extremely urban-tough
- Kentucky coffeetree (Gymnocladus dioicus) — heat-tolerant, no significant pest issues
- Swamp white oak, northern red oak, sugar maple (suburban yards away from salt zones)
Trees to Avoid in the Lehigh Valley
- Callery/Bradford pear — banned in Pennsylvania as of 2024; brittle, invasive
- Norway maple — invasive; not recommended for new planting
- Tree-of-heaven — invasive; preferred SLF host
- Untreated white or green ash — guaranteed loss to EAB
- Silver maple in small urban yards — brittle, root-aggressive, storm-prone
11. Penn State Extension and Local Resources
- Penn State Extension — Lehigh County: 610-391-9840
- Penn State Extension — Northampton County: 610-813-6613
- Spotted Lanternfly hotline: 1-888-4BAD-FLY (1-888-422-3359)
- PPL Electric (tree and line issues): 1-800-342-5775
- ISA “Find a Certified Arborist”: treesaregood.org
- Pennsylvania DCNR — Forests and Trees: dcnr.pa.gov
- PA iMapInvasives: report invasive species statewide
Stone Ridge Landscaping LLC has served Lehigh and Northampton Counties for 25 years. We provide free on-site assessments for tree removal, trimming, hazard evaluation, and lot clearing throughout the Valley.