Pennsylvania’s diverse climate and soil conditions make it an excellent location for gardening enthusiasts. Whether you’re a beginner or an experienced gardener, this guide will help you navigate the unique challenges and opportunities of gardening in the Keystone State.
Understanding Pennsylvania’s Growing Zones
Pennsylvania spans several USDA plant hardiness zones, which are geographic areas defined by the average annual minimum winter temperature. The zones in Pennsylvania include:
- Zone 5a: -20 to -15°F
- Zone 5b: -15 to -10°F
- Zone 6a: -10 to -5°F
- Zone 6b: -5 to 0°F
- Zone 7a: 0 to 5°F
- Zone 7b: 5 to 10°F
- Zone 8a: 10 to 15°F (small section)
The majority of Pennsylvania falls within Zones 6a and 6b, which experience average minimum winter temperatures of -10 to -5°F and -5 to 0°F, respectively.
Frost Dates
In addition to plant hardiness zones, understanding the average first and last frost dates in your area is crucial for planning your garden. Frost dates indicate when you can safely plant frost-sensitive crops outdoors without the risk of damage from cold temperatures. Pennsylvania’s last frost dates range from mid-April to early June, depending on your location. Some examples of last frost dates for cities in Pennsylvania include:
- Philadelphia: April 14
- Pittsburgh: May 26
- Harrisburg: May 4
- Scranton: May 21
First frost dates in Pennsylvania typically occur between mid-September and late October.
Growing Season Length
The length of the growing season in Pennsylvania varies depending on your location and hardiness zone. On average, Pennsylvania has approximately 150 days between the last and first frost. This means that most areas of the state have a sufficient growing season for a wide range of vegetables, fruits, and ornamental plants.
Microclimates
It’s important to note that even within a specific hardiness zone, microclimates can exist due to factors such as elevation, proximity to water, and urban heat islands. These microclimates can influence the actual minimum winter temperatures and frost dates in a particular location. For example, areas near large bodies of water, such as Lake Erie, may experience milder winter temperatures and a longer growing season compared to inland areas in the same hardiness zone.
Choosing the Right Plants
When selecting plants for your Pennsylvania garden, consider native species that are well-adapted to the local climate and ecosystem. Native plants not only thrive with minimal maintenance but also support local pollinators and wildlife.
Native Plants
Native plants are an excellent choice for Pennsylvania gardens because they are well-adapted to the local climate and ecosystem. They have evolved over time to thrive in the specific soil, moisture, and sunlight conditions of the region, making them low-maintenance and easy to care for once established. Some popular native plants for Pennsylvania gardens include:
- Black-eyed Susan (Rudbeckia hirta): A cheerful, yellow daisy-like flower that blooms from summer to fall
- Purple Coneflower (Echinacea purpurea): A sturdy, drought-tolerant perennial with purple-pink flowers that attract butterflies and other pollinators
- Butterfly Weed (Asclepias tuberosa): A vibrant orange milkweed that serves as a host plant for monarch butterflies
- Wild Columbine (Aquilegia canadensis): A delicate, red and yellow flower that thrives in partial shade and attracts hummingbirds
Other native plant options include trees like Eastern Hemlock (Tsuga canadensis) and Red Maple (Acer rubrum), shrubs like American Elderberry (Sambucus canadensis) and Highbush Blueberry (Vaccinium corymbosum), and grasses like Little Bluestem (Schizachyrium scoparium). By incorporating native plants into your garden, you not only create a beautiful, low-maintenance landscape but also support local biodiversity by providing food and shelter for pollinators and wildlife.
Vegetables and Herbs
In addition to native plants, many vegetables and herbs can be successfully grown in Pennsylvania gardens. The key is to choose varieties that are well-suited to your specific growing zone and to plant them at the appropriate time.
Cool-season crops like lettuce, spinach, peas, and kale can be planted in early spring or fall when temperatures are cooler. These crops thrive in the mild weather and can often be harvested multiple times throughout the season.
Warm-season crops like tomatoes, peppers, and squash should be planted after the last frost date in your area, which can range from mid-April to early June depending on your location. These crops require warm soil and air temperatures to grow and produce fruit. When selecting vegetable and herb varieties, look for those that are well-adapted to your specific growing conditions.
Consider factors like the amount of sunlight your garden receives, the type of soil you have, and the length of your growing season.
Some popular vegetable and herb varieties for Pennsylvania gardens include:
- Tomatoes: ‘Brandywine’, ‘Sungold’, ‘Roma’
- Peppers: ‘California Wonder’, ‘Jalapeño’, ‘Sweet Banana’
- Lettuce: ‘Buttercrunch’, ‘Romaine’, ‘Red Leaf’
- Basil: ‘Genovese’, ‘Thai’, ‘Purple Ruffles’
- Parsley: ‘Italian Flat Leaf’, ‘Curly Leaf’
By choosing a mix of native plants, vegetables, and herbs that are well-suited to your specific growing conditions, you can create a diverse, productive, and beautiful garden that thrives in the Pennsylvania climate.
Preparing Your Garden Beds
Clearing the Garden Bed
Before you begin planting, it’s essential to clear your garden bed of any debris, weeds, and remaining plant material from the previous season. This helps prevent disease and pest issues from carrying over to the new growing season. Start by removing any visible weeds, including their roots, to prevent them from resprouting.
If you have persistent perennial weeds, you may need to use a herbicide or cover the area with a thick layer of mulch to smother them. Next, remove any dead or decaying plant material from the previous season, such as old vegetable plants or annual flowers. This material can harbor pests and diseases, so it’s best to dispose of it in the trash or a separate compost pile.
Improving Soil Quality
Once your garden bed is clear, it’s time to focus on improving soil quality. Pennsylvania soils can vary widely in terms of texture, fertility, and pH, so it’s important to assess and amend your soil as needed. One of the best ways to improve soil structure and fertility is by incorporating organic matter, such as compost or well-rotted manure. Organic matter helps to:
- Improve soil structure and aeration
- Increase water retention and drainage
- Provide essential nutrients for plant growth
- Support beneficial soil microorganisms
To incorporate organic matter, spread a 2-3 inch layer over the surface of your garden bed and mix it into the top 6-8 inches of soil using a garden fork or tiller.
Soil Testing
If you’re starting a new garden or have never had your soil tested, it’s a good idea to have a soil test done before planting. Soil tests can provide valuable information about your soil’s pH, nutrient levels, and organic matter content, which can help you make informed decisions about soil amendments and plant selection.
You can obtain a soil test kit from your local Penn State Extension office or a private soil testing lab. Follow the instructions carefully for collecting and submitting your soil sample. Once you receive your soil test results, you can use the information to adjust your soil pH (if needed) and add any necessary nutrients, such as nitrogen, phosphorus, or potassium.
Raised Beds and Container Gardens
If you have poor soil quality or limited space, consider creating raised beds or container gardens. Raised beds allow you to control the soil quality and drainage, while container gardens are perfect for small spaces or areas with contaminated soil. To create a raised bed, build a frame using untreated wood, stone, or concrete blocks, and fill it with a mixture of high-quality topsoil and organic matter.
For container gardens, choose pots or planters with adequate drainage holes and fill them with a well-draining potting mix. By properly preparing your garden beds before planting, you can create a healthy and productive growing environment for your plants. Taking the time to clear debris, improve soil quality, and test your soil will pay off in the long run with better plant growth and yields.
Planting and Maintenance
When planting, follow the recommended spacing and depth for each crop, and water thoroughly after planting. As your plants grow, provide regular care, including watering, fertilizing, and mulching to suppress weeds and retain moisture. Monitor your plants for signs of pests or disease, and take appropriate action if necessary, such as using organic pest control methods or removing affected plant parts.
Dealing with Invasive Species
Common Invasive Plants in Pennsylvania
Several invasive plant species have become problematic in Pennsylvania, threatening native ecosystems and biodiversity. Some of the most common invasive plants include:
- Japanese Knotweed (Fallopia japonica): This aggressive perennial forms dense thickets, outcompeting native vegetation. It spreads rapidly through rhizomes and can regenerate from small stem or root fragments
- Garlic Mustard (Alliaria petiolata): This biennial herb forms dense stands in forest understories, displacing native wildflowers. It produces large quantities of seeds that can remain viable in the soil for several years
- Purple Loosestrife (Lythrum salicaria): This wetland perennial forms dense monocultures, reducing plant and animal diversity in wetland habitats. Each plant can produce over 2 million seeds annually
Other problematic invasive plants in Pennsylvania include oriental bittersweet, multiflora rose, Japanese barberry, and mile-a-minute vine.
Preventing the Spread of Invasive Species
To minimize the spread of invasive plants, gardeners should take the following steps:
- Avoid planting known invasive species in your garden. Research plants before purchasing to ensure they are not invasive in your area
- Remove any existing invasive plants from your property using appropriate methods (see below). Monitor the area for regrowth and remove any new seedlings or sprouts
- Dispose of invasive plant material properly. Bag and dispose of seeds, fruits, and plant parts in the trash, not in compost or yard waste
- Plant native species instead of exotic ornamentals. Native plants support local ecosystems and are less likely to become invasive
Controlling Invasive Plants
The most effective method for controlling invasive plants depends on the species and the extent of the infestation. Some general control strategies include:
- Manual removal: For small infestations, hand-pulling or digging out the entire plant, including the roots, can be effective. Repeat as necessary to exhaust the seed bank
- Cutting or mowing: Repeatedly cutting back the foliage of invasive plants can weaken them over time. Mow or cut before the plants set seed to prevent further spread
- Smothering: Cover small patches of invasive plants with thick mulch, cardboard, or black plastic to deprive them of light. Leave the covering in place for at least one growing season
- Herbicides: For large infestations, herbicides may be necessary. Choose an appropriate herbicide for the target species and follow all label instructions carefully. Consult with your local extension office for guidance
Controlling invasive plants requires persistence and long-term management. Monitor treated areas for several years and remove any new growth promptly. By avoiding the introduction of invasive plants, removing existing infestations, and promoting native species, Pennsylvania gardeners can help protect local ecosystems and preserve biodiversity in their landscapes.
Enjoying Your Pennsylvania Garden
Gardening in Pennsylvania can be a rewarding and enjoyable experience, providing fresh produce, beautiful flowers, and a connection to nature. By understanding your growing zone, selecting the right plants, and providing proper care and maintenance, you can create a thriving garden that enhances your landscape and supports local biodiversity.
