Discover Pennsylvania’s Planting Zones – Plus 11 Keys To Keeping Flowers, Shrubs, and Trees Alive

Written by Em Casalena
Updated: October 25, 2023
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Nestled in the heart of the northeastern United States lies Pennsylvania, a state brimming with natural beauty and a diverse range of landscapes. From the rolling hills of the Pocono Mountains to the bustling urban landscapes of Philadelphia and Pittsburgh, Pennsylvania is a place of contrasts and surprises. But what makes this state unique is its planting zones, the secret behind its lush gardens and thriving flora. Let’s dive into these planting zones and see what can grow there!

Understanding Hardiness Zones

Hardiness zone maps, also known as planting zone maps, play a crucial role in helping gardeners and plant enthusiasts select the right plants for their local climate. These maps are essential tools for anyone looking to create a thriving garden or landscape. Even if you live in what you consider a temperate area that can grow almost anything, these maps provide some context to help you choose the right plant species and when to plant them.

What Are Hardiness Zone Maps?

Hardiness zone maps are geographical guides that divide regions into zones based on the average annual minimum temperatures. Each zone represents a range of temperatures within which plants are most likely to thrive. The United States Department of Agriculture (USDA) and various horticultural organizations have developed these maps to aid gardeners and horticulturists in selecting plants suited to their specific climates.

Hardiness zone or planting zone maps can make all the difference for professional farmers and hobby gardeners alike who want to understand what can and cannot grow in their specific geographical area and microclimate.

© – License

Why Are They Important?

Plants have specific temperature requirements for growth and survival. By choosing plants that match your hardiness zone, you increase the chances of their survival and overall health. Plants that can withstand your local minimum temperatures are more likely to flourish in your garden.

Also, hardiness zone maps help you make informed decisions about plant selection. When you choose plants that are well-suited to your zone, you reduce the need for extensive care and maintenance. This efficiency saves you time, money, and effort in the long run.

How to Use Hardiness Zone Maps

Start by determining your hardiness zone. You can find this information on hardiness zone maps provided by the USDA or local gardening organizations. Most maps divide regions into zones ranging from 1 (coldest) to 13 (warmest). Locate your region to determine your specific zone.

Once you know your hardiness zone, choose plants that are recommended for that zone. Plant labels, catalogs, and online resources often include zone information for each plant species. Select plants that fall within your zone’s temperature range to ensure their success.

Next, you should consider your microclimate. Microclimates are localized climate variations within your garden or landscape. Factors like shade, wind patterns, and urban heat can create microclimates that differ from your overall zone. Be aware of these variations and select plants accordingly. For instance, a sunny spot near a building may have a slightly different microclimate than a shaded area.

While planting zones in Pennsylvania offer valuable guidance, they are based on historical temperature data. Climate change and other factors can lead to occasional temperature extremes. Stay vigilant by monitoring weather forecasts and be prepared to protect your plants during unexpected cold snaps.

Gardening is a dynamic process, and not all plants will thrive as expected. Don’t be discouraged by occasional setbacks. Experiment with different plant varieties and adapt your garden over time to find the best combination for your specific location.

Pennsylvania’s Hardiness Zones and Plants That Thrive There

Zone 4b and 5a: Northern Pennsylvania

The northern parts of Pennsylvania, including cities like Erie, fall within the ambit of hardiness zones 4b and 5a. These zones are characterized by cold winters with average minimum temperatures plummeting to -25 degrees F to -15 degrees F in Zone 4b and -20 degrees F to -15 degrees F in Zone 5a.

In Zone 4b, where winters are especially harsh, hardy plants are a must. You’ll find resilient species like the White Spruce thriving in these extreme conditions, with their evergreen foliage providing year-round greenery.

In Zone 5a, slightly less severe winters allow for a broader range of plant life. The Black-Eyed Susan, with its cheerful yellow blooms, is a common sight in gardens during the short growing season.

Erie, Pennsylvania

Northern Pennsylvania, especially in lakeside cities like Erie, is well-known for having very harsh winter weather that only the hardiest of plants can survive.

© Pavone

Zone 6a and 6b: Central Pennsylvania

Central Pennsylvania, encompassing regions near Harrisburg and State College, corresponds to planting zones 6a and 6b. These zones bring milder winters with average minimum temperatures fluctuating between -10 degrees F to -5 degrees F in Zone 6a and -5 degrees F to 0 degrees F in Zone 6b.

The milder winters in these zones open up opportunities for a broader selection of plants. Japanese Maples with their striking, colorful leaves are popular ornamental trees in this region. Meanwhile, Daylilies, renowned for their vibrant blooms, grace gardens during the growing season.

Zone 7a and 7b: Southeastern Pennsylvania

Southeastern Pennsylvania, comprising areas around Philadelphia, features zones 7a and 7b. These zones are marked by even milder winters, with average minimum temperatures spanning from 0 degrees F to 5 degrees F in Zone 7a and 5 degrees F to 10 degrees F in Zone 7b.

In Zone 7a, gardeners can cultivate a variety of plants, including roses, such as the Knock Out and David Austin varieties, which thrive in the favorable climate, producing abundant, colorful blooms. Azaleas, known for their vibrant spring blossoms, are also well-suited to this zone.

Zone 7b, with slightly warmer winters, allows for a broader range of plant choices. Camellias, evergreen shrubs, dazzle with waxy flowers during the winter months. Creeping Phlox, a ground cover plant, blankets gardens with colorful spring flowers, making it ideal for borders and rock gardens.

Zone 6b: Southwestern Pennsylvania

Southwestern Pennsylvania, home to cities like Pittsburgh, primarily corresponds to hardiness zone 6b. This zone shares similarities with Central Pennsylvania in terms of climate, featuring moderate winters with average minimum temperatures ranging from -5 degrees F to 0 degrees F.

This zone is conducive to a diverse range of plants, similar to Central Pennsylvania. Lilacs, known for their fragrant blossoms, are beloved additions to gardens here. Additionally, various Hydrangea species, including the Bigleaf and Panicle hydrangeas, flourish in this temperate climate, offering stunning flowers and foliage.

Zone 5b: North and Northwest Pennsylvania

The northwestern corners of Pennsylvania, around Erie and Bradford, fall into hardiness zone 5b. This region experiences cooler winters with average minimum temperatures fluctuating between -15 degrees F to -10 degrees F.

Plants that thrive in Zone 5b often overlap with those in the colder zones of Northern Pennsylvania. White Spruce is a resilient evergreen tree that can withstand the chill, offering year-round greenery. Black-Eyed Susan, with its cheerful yellow blooms, adds warmth to the landscape during the short growing season.

Zone 6b and 7a: North Central Pennsylvania

North Central Pennsylvania, near cities like Williamsport and Lock Haven, experiences a mix of hardiness zones 6b and 7a. This transition zone sees somewhat milder winters in Zone 6b and slightly warmer winters in Zone 7a.

Plant selections in this region may mirror those in Central Pennsylvania and Southeastern Pennsylvania, respectively. In Zone 6b, you’ll find familiar choices like Lilacs and Hydrangeas. In Zone 7a, Roses and Azaleas thrive similarly to their counterparts in Southeastern Pennsylvania.

Zone 7b: Southeastern Coastal Areas

The southeastern coastal regions of Pennsylvania, along the Delaware River and bordering the state of Delaware, are nestled within hardiness zone 7b. With milder winters, this zone enjoys average minimum temperatures ranging from 5 degrees F to 10 degrees F.

Plants that flourish in this zone align closely with those in Southeastern Pennsylvania’s Zone 7b. Roses, including the Knock Out and David Austin varieties, produce abundant blooms, while Azaleas grace gardens with their vibrant spring blossoms.

Tips for Keeping Shrubs, Trees, and Flowers Alive in Pennsylvania

Maintaining a thriving garden in Pennsylvania, with its varied climates and landscapes, can be a rewarding yet challenging endeavor. From the rolling hills of the Appalachian Mountains to the bustling cityscapes of Philadelphia, the state offers a wide range of conditions for plants to flourish. To help you achieve success in keeping your shrubs, trees, and flowers healthy and vibrant, here are essential tips and best practices.

1. Know Your Hardiness Zone

Understanding your local hardiness zone is the first step in selecting the right plants for your garden. Pennsylvania spans a spectrum of zones, from 4b in the northwestern regions to 7b in the southeastern coastal areas. Each zone reflects the average annual minimum temperatures, which significantly impact plant survival. Choosing plants that are well-suited to your zone ensures they can endure the winter cold and thrive in the summer heat.

2. Select Native Plants

Native plants are well-adapted to Pennsylvania’s specific climate and soil conditions. They have evolved to thrive in the region, making them hardier and more resilient. When you incorporate native species into your garden, you reduce the need for excessive care, such as watering and pest control. Native plants also support local wildlife, attracting beneficial pollinators like bees and butterflies.

New England Aster, Aster, Butterfly - Insect, Color Image, Flower

New England Aster is one of hundreds of native plants that have grown in Pennsylvania for centuries. Choosing native plants is a great way to ensure the longevity of your Pennsylvania garden, regardless of your specific planting zones.

©John Byers/ via Getty Images

3. Proper Planting Techniques

Planting shrubs, trees, and flowers correctly is essential for their long-term health. Ensure that you dig a hole of the appropriate depth and width for the plant’s root system. Planting too deeply or too shallowly can stress the plant. Be mindful of the plant’s root ball, and make sure it is level with the surrounding soil. Water thoroughly after planting to eliminate air pockets and provide the plant with essential moisture.

4. Mulching Matters

Pennsylvania plant zones tend to all have one thing in common; they are all fairly chilly, as most of the New England region is. For places that might suffer from frozen ground, mulching can be beneficial. Mulching offers numerous benefits for plant health. It helps retain soil moisture, regulates soil temperature, and suppresses weeds that can compete for nutrients. Apply a layer of mulch around the bottom of your plants, keeping it away from the plant’s trunk or stems to prevent rot. Choose organic mulches like wood chips or compost, as they enrich the soil as they break down.

5. Water Wisely

Proper watering is crucial for plant health, especially in Pennsylvania, where precipitation can vary significantly throughout the year. Water deeply but infrequently to encourage deep root growth and drought tolerance. Morning is the best time to water, allowing leaves to dry before evening and reducing the risk of fungal diseases. Consider using some type of drip irrigation system or even basic soaker hoses to provide water directly to the roots instead of wasting water.

6. Pruning and Maintenance

Regular pruning and maintenance help keep your plants healthy and shapely. Prune dead or diseased branches to encourage new growth and improve air circulation. Trim overgrown shrubs to maintain their shape and prevent overcrowding. Be mindful of the specific pruning requirements of different plants, as improper pruning can harm rather than help.

7. Soil Health

Healthy soil is the foundation of a thriving garden. Conduct a soil test to determine its pH and nutrient levels. Amend the soil as needed to achieve the optimal pH for your chosen plants. Adding organic matter like compost improves soil structure, moisture retention, and nutrient availability. Mulching also contributes to soil health over time.

8. Pest and Disease Management

Vigilance is key to preventing and managing pests and diseases in your garden. Regularly inspect your plants for signs of trouble, such as discolored or damaged leaves, unusual growth, or insect infestations. Identify the problem accurately before applying any treatments, as different pests and diseases require specific solutions. Consider using integrated pest management (IPM) techniques, which focus on prevention and minimal chemical intervention.

9. Fertilization

Applying fertilizer can provide essential nutrients that promote plant growth and flowering. However, it’s crucial to follow a fertilization schedule appropriate for your specific plants. Over-fertilization can lead to nutrient imbalances and environmental issues. Use a balanced, slow-release fertilizer and apply it according to the recommended rates on the product label.

10. Winter Protection

Pennsylvania experiences cold winters, particularly in the northern regions. Protecting your plants from harsh winter conditions is essential for their survival. Consider wrapping young trees with burlap to shield them from freezing winds and sunscald. Apply a thick layer of mulch around the base of shrubs to insulate their roots. In extreme cold, consider using plant covers or burlap to shield delicate flowers and shrubs.

11. Regular Monitoring and Adaptation

Lastly, keep a watchful eye on your garden throughout the seasons. Conditions can change due to weather, pests, or other factors. Adjust your care regimen as needed. If a particular plant isn’t thriving, consider relocating it to a more suitable spot or replacing it with a more appropriate species. Gardening requires ongoing attention and adaptation to ensure the best outcomes.

Maintaining healthy shrubs, trees, and flowers in Pennsylvania’s diverse environments demands a combination of knowledge, care, and adaptability. By understanding your hardiness zone, selecting native plants, practicing proper planting techniques, mulching wisely, watering effectively, and following best practices for pruning, soil health, pest and disease management, fertilization, and winter protection, you can cultivate a garden that thrives year-round. Regular monitoring and adaptation will ensure your garden remains vibrant and resilient in the ever-changing Pennsylvania climate.

Gardening in the Keystone State offers endless possibilities for beauty and growth, and with the right strategies, you can achieve success and fulfillment in nurturing your green oasis. Happy planting!

The photo featured at the top of this post is © Meredith Heil/

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About the Author

Em Casalena is a writer at A-Z Animals where their primary focus is on plants, gardening, and sustainability. Em has been writing and researching about plants for nearly a decade and is a proud Southwest Institute of Healing Arts graduate and certified Urban Farming instructor. Em is a resident of Arizona and enjoys learning about eco-conscious living, thrifting at local shops, and caring for their Siamese cat Vladimir.

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