Philadelphia Planting Zone: What You Need to Know
Philadelphia, Pennsylvania, primarily falls within USDA plant hardiness zone 7a and 7b. This classification is crucial for gardeners and landscapers in Philadelphia because it indicates the average minimum winter temperatures, helping them choose plants that can survive the region’s cold season.
Understanding USDA Plant Hardiness Zones
The USDA plant hardiness zones are geographic areas defined by average minimum winter temperatures. Developed by the U.S. Department of Agriculture (USDA), these zones help gardeners determine which plants are most likely to thrive in a specific location. The lower the zone number, the colder the average winter temperature.
Philadelphia’s Zone: 7a and 7b Explained
Philadelphia is largely situated within zones 7a and 7b. Zone 7a experiences average minimum winter temperatures between 0°F to 5°F (-17.8°C to -15°C), while zone 7b experiences average minimum winter temperatures between 5°F to 10°F (-15°C to -12.2°C). Due to the urban heat island effect, some pockets within the city might experience slightly warmer microclimates, potentially blurring the lines between the two zones.
Implications for Gardeners in Philadelphia
Knowing your specific planting zone is essential for selecting appropriate plants. Plants labeled as hardy to zone 7 or lower should generally survive Philadelphia winters. It is worth noting that plant tags will often list the plant hardiness zone. You can always seek advice from a local nursery or experienced gardener.
Choosing the Right Plants
Focus on plants that are hardy to zones 7a or 7b. Consider native plants, which are already adapted to the local climate and soil conditions. Native plants generally require less maintenance and are beneficial for local wildlife.
Protecting Sensitive Plants
While zone information provides a guideline, extreme weather events can still occur. Consider providing extra protection to more delicate plants during harsh winters. This might include mulching, wrapping, or moving potted plants indoors.
Frequently Asked Questions
What happens if I plant something not suited for zone 7?
If you plant something that isn’t hardy to zone 7, it may not survive the winter. It could experience dieback, or even die completely if it can’t tolerate the cold.
Are there microclimates in Philadelphia that affect planting?
Yes, urban areas often have microclimates that are warmer than surrounding rural areas due to the “urban heat island effect.” This can allow you to grow plants that are slightly less hardy than what would normally be recommended for zone 7.
Where can I find more information about Philadelphia-specific gardening tips?
Local nurseries, gardening clubs, and the Penn State Extension office are great resources for Philadelphia-specific gardening advice.
Does the planting zone affect when I should start seeds indoors?
Yes, knowing your planting zone helps you determine the last frost date, which is crucial for planning when to start seeds indoors and transplant them outdoors.
Can I use row covers to extend the growing season in Philadelphia?
Yes, row covers are a good option to protect plants from light frost and extend your growing season. Other options include cold frames and greenhouses.
Summary
Philadelphia’s plant hardiness zones, primarily 7a and 7b, are critical for successful gardening. By understanding these zones and selecting plants accordingly, Philadelphia gardeners can create thriving and beautiful landscapes that withstand the region’s winter conditions. Remember to consider microclimates and take necessary precautions to protect sensitive plants during harsh weather.
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