Ideas For Drought-Tolerant Trees In Pennsylvania Landscapes

Introduction

Pennsylvania’s climate ranges from cool, humid in the northwest and high elevations to warmer, more moderate conditions in the southeast. Summers can be hot and occasionally dry, especially in urban settings or on well-drained upland soils. Choosing drought-tolerant trees for the landscape reduces water demand, improves survival during dry spells, and lowers maintenance. This article outlines practical, site-sensitive choices for drought-tolerant trees that perform well in Pennsylvania, plus planting and care strategies to help them thrive.

How to think about drought tolerance in Pennsylvania

Drought tolerance is not an absolute trait; it depends on soil, microclimate, tree age, and care. A tree that survives drought on a well-drained, sunny slope may suffer in compacted clay at the bottom of a yard, and vice versa. Consider these factors when selecting species:

• Soil texture: Sandy soils drain quickly and hold less water; clay holds water but can be compacted and limit roots.
• Exposure: Full sun and southerly exposures increase evapotranspiration and drought stress.
• Rooting space and compaction: Urban lawns with limited rooting volume increase drought vulnerability.
• Establishment phase: Most trees need supplemental water for the first two to three growing seasons.
• Native vs. non-native: Native species are often better for wildlife and local pests, but some non-natives perform well and are advisable in urban conditions.

Recommended drought-tolerant trees for Pennsylvania

Below is a selection of trees well-suited to Pennsylvania landscapes that are known for drought tolerance, adaptation to a range of soils, and landscape value. For each tree I include site notes, mature size, and practical tips.

• Bur oak (Quercus macrocarpa)
• Site notes: Excellent drought tolerance; tolerant of poor, dry soils; performs best in full sun.
• Size: 50-70+ ft tall and wide; broad crown.
• Tip: Slow to establish but long-lived and excellent for wildlife (acorns feed birds and mammals).
• White oak (Quercus alba)
• Site notes: Moderately drought tolerant once established; prefers well-drained soils; native and valuable to wildlife.
• Size: 50-80 ft tall; stately form.
• Tip: Plant in locations where a long-lived specimen is desired; avoid compacted sites without remediation.
• Honeylocust, thornless varieties (Gleditsia triacanthos var. inermis)
• Site notes: Highly tolerant of drought and urban soils; light, filtered shade allows lawn and understory plants beneath.
• Size: 30-70 ft tall depending on cultivar.
• Tip: Choose cultivars selected for thornlessness and disease resistance. Good street or lawn tree.
• Hackberry (Celtis occidentalis)
• Site notes: Very tolerant of drought, compacted soils, and urban stress; adaptable.
• Size: 40-60 ft tall.
• Tip: Provides small fruit eaten by birds; consider placement due to messy fruit if near walks.
• Kentucky coffeetree (Gymnocladus dioicus)
• Site notes: Extremely drought tolerant and tolerant of poor soils; coarse texture so it fits large landscapes.
• Size: 50-70 ft tall.
• Tip: Male cultivars avoid large messy seed pods. Plant where its rugged branching is appropriate.
• Ginkgo (Ginkgo biloba), male cultivars
• Site notes: Excellent tolerance for drought, heat, and urban pollution; very tough in a variety of soils.
• Size: 50-80 ft tall; pyramidal to spreading habit.
• Tip: Use male cultivars to avoid malodorous fruit. A long-lived, low-maintenance urban specimen.
• Eastern redbud (Cercis canadensis)
• Site notes: Moderately drought tolerant once established; bright spring flowers and manageable size.
• Size: 20-30 ft tall.
• Tip: Best in well-drained soils and partial to full sun. Good for smaller yards or as a focal understory tree.
• Serviceberry (Amelanchier spp.)
• Site notes: Several species and cultivars vary in drought tolerance; Amelanchier laevis and Amelanchier arborea adapt well once established.
• Size: 15-25 ft tall for many varieties.
• Tip: Excellent seasonal interest (flowers, fruit, fall color) and wildlife value; tolerate drier soils better than many spring-flowering small trees.
• Eastern red cedar (Juniperus virginiana)
• Site notes: A native evergreen that tolerates dry, poor soils and heat; useful for windbreaks or in rural landscapes.
• Size: 20-40+ ft tall depending on form.
• Tip: Can naturalize; consider planting location and seed dispersal by birds.
• Black locust (Robinia pseudoacacia)
• Site notes: Tolerates drought and poor soils; nitrogen-fixer that can improve poor sites.
• Size: 30-70 ft tall.
• Tip: Vigorous and suckering; some cultivars are less invasive. Beware of brittle wood and potential aggressive spread.

Species to avoid or use cautiously

Not all trees that survive short dry spells are good long-term choices for drought-prone sites. Some common mistakes:

• Avoid planting ash (Fraxinus spp.) because of emerald ash borer losses.
• Avoid trees known to be invasive or highly weedy in the region (for example, tree-of-heaven, Ailanthus altissima) even though they tolerate drought.
• Avoid species that need consistent moisture such as paper birch (Betula papyrifera), river birch (Betula nigra) in truly dry sites.
• Maples like sugar maple (Acer saccharum) and red maple (Acer rubrum) are shade-loving and often suffer in hot, dry exposures.

Planting and establishment best practices

Site assessment and selection

• Evaluate soil texture with a simple jar test or by feel; sandy soils need more organic matter to retain moisture, while compacted clay may need remediation.
• Observe microclimates: south- and west-facing slopes and urban heat islands dry out faster.
• Group plants by water needs (hydrozoning) so drought-tolerant trees are not placed with moisture-loving shrubs.

Planting technique and soil preparation

• Plant trees at the correct depth: root flare should be at or slightly above final grade. Do not bury the trunk.
• Avoid over-amending backfill with potting soil in large amounts; create a transition zone of native soil blended with compost if needed to avoid a “bathtub” effect.
• For compacted sites, consider vertical mulching or mechanical loosening of the top foot of soil to improve rooting.

Mulch, watering, and irrigation

• Mulch 2-4 inches of organic mulch (wood chips or shredded bark) over the root zone, extending to the dripline if possible, but keep mulch pulled back 2-4 inches from the trunk.
• Establishment watering is crucial. As a rule of thumb:
• First growing season: deep soak twice per week during dry weather (apply enough water to wet the root zone 12-18 inches deep).
• Second year: reduce to once weekly deep waterings as needed.
• Third year and beyond: supplemental irrigation only during extended droughts, using deep, infrequent watering.
• Use soaker hoses or slow-drip irrigation for efficient, deep root wetting.

Pruning and protection

• Prune only to remove dead or crossing branches until the tree is established. Avoid heavy pruning immediately after planting.
• Stake only when necessary and remove stakes after one growing season to allow trunk strengthening.
• Protect young trunks from lawn mower damage and rodents; a simple trunk guard can prevent girdling.

Landscape design and diversity

Drought-tolerant landscaping does not mean planting a single species everywhere. Long-term resilience comes from diversity.

• Mix species of different genera to reduce pest and disease risk.
• Combine canopy trees with drought-tolerant understory shrubs and perennials to create layered, water-wise plantings.
• Use swales, rain gardens, and contouring to capture runoff and direct it to tree root zones during storms.
• Consider soil-improving practices like periodic top-dressing with compost to increase moisture retention and soil health.

Monitoring and adaptive care

Trees that are drought tolerant still need observation. Watch for signs of stress: early leaf drop, wilting, scorched leaf margins, thinning canopy, and dieback. Respond by:

• Checking soil moisture a few inches below the surface before watering.
• Increasing deep water applications during prolonged heat waves or drought.
• Improving soil organic matter in future seasons to increase resilience.

Practical takeaways

• Choose trees that match the site: soil type, exposure, and available rooting volume.
• Prioritize natives like oaks, hackberry, and bur oak for ecological benefits, but include hardy non-natives like ginkgo or male Kentucky coffeetree where appropriate.
• Plant correctly: shallow planting, proper mulching, and focused establishment watering are more important than species selection alone.
• Group plants by water needs and avoid mixing moisture-loving species into dry landscapes.
• Maintain species diversity to reduce vulnerability to pests and changing climatic conditions.

Conclusion

Drought-tolerant trees can provide long-term shade, wildlife habitat, and aesthetic value to Pennsylvania landscapes while reducing irrigation needs. By selecting species adapted to local conditions, planting correctly, and providing targeted care through the crucial establishment period, homeowners and landscapers can build resilient, low-water tree canopies that continue to mature and provide benefits for generations.