When To Plant Flowers In Pa

Knowing when to plant flowers in PA is the first step to a beautiful garden all season long. Pennsylvania’s varied climate means timing is everything, and this guide will help you get it right.

Our state has everything from cold mountain zones to warmer southeastern areas. This means your planting dates can shift by several weeks. We’ll break it down by season and flower type so you can plan with confidence.

This heading is your roadmap. The best time to plant depends on what your planting. Are they tough seeds that need winter’s chill? Or tender annuals that hate frost? Let’s look at the factors that set your schedule.

Understanding Pennsylvania’s Planting Zones

Most of Pennsylvania falls within USDA Hardiness Zones 5b to 7a. This is a measure of the average coldest winter temperature. It tells you which perennial plants can survive your winters.

Check your specific zone:

Zones 5b & 6a (Colder): Northern tier, high elevations. Shorter growing season.
Zones 6b & 7a (Warmer): Southeastern PA, Philadelphia area. Longer, milder seasons.

Your zone is crucial for perennials, trees, and shrubs. For annual flowers, the last spring frost date is more important. This date is when it’s typically safe to plant tender things.

The Last Frost Date is Your Key

This is the average date of the last light freeze in spring. Gardeners watch this closely. Planting too early can damage or kill sensitive plants.

General last frost timelines for PA:

Southcentral & Southeastern PA: Late April to early May.
Central & Northeastern PA: Mid to late May.
Northwestern & High Elevations: Late May to early June.

Always check a local gardening calendar for your exact town. A good rule is to wait 1-2 weeks after this date for warm-weather flowers.

Planting Hardy Annuals & Perennials in Early Spring

Some plants tolerate cold and can go in the ground early. This gives them a head start. Hardy annuals and dormant perennials are you best choices here.

You can plant these as soon as the soil is workable (not frozen or soggy):

Pansies & Violas: They handle light frosts beautifully.
Snapdragons & Dianthus: Another good choice for cool weather.
Dormant Perennials: Plants like daylilies or hostas bought bare-root.
Cold-Tolerant Seeds: Sweet peas, larkspur, poppies.

Early spring is also perfect for dividing existing perennials that have become overgrown.

Planting Tender Annuals & Summer Bulbs After Frost

This is the main planting rush. All plants that love heat and hate cold go in now. The soil and air have warmed up enough for them to thrive.

Wait until after your last frost date for these:

Petunias, Marigolds, Zinnias: Classic summer bedding plants.
Impatiens & Begonias: For those shady spots.
Summer Bulbs: Dahlias, gladiolus, cannas.
Vegetable Transplants: Like tomatoes and peppers.

If you get a surprise late frost warning, cover tender plants with a cloth or bucket overnight.

Fall Planting for a Head Start Next Year

Fall is a fantastic, often overlooked, planting season. The soil is still warm, but the air is cool. This encourages root growth without the stress of summer heat.

Plant in early fall (6 weeks before first frost) for best results:

Spring-Blooming Bulbs: Tulips, daffodils, crocus. They need winter chilling.
Perennials: Establishing roots now means bigger plants next spring.
Hardy Annual Seeds: Like calendula or bachelor’s buttons, they’ll sprout early.
Trees & Shrubs: Excellent time for them to settle in.

Fall planting also means less watering and fewer weeds to compete with.

A Seasonal Planting Calendar for Pennsylvania

Here’s a quick-reference guide to keep you on track throughout the year.

Late March – April (Early Spring)

Start seeds indoors for tomatoes, peppers, and slow flowers.
Direct sow hardy annual seeds if soil is workable.
Plant bare-root perennials and roses.
Prune summer-blooming shrubs.

May – Early June (Late Spring)

Harden off indoor-started plants for 7-10 days.
Plant tender annuals and summer bulbs after frost danger passes.
Set out warm-season vegetable transplants.
Apply mulch to conserve moisture and supress weeds.

September – October (Fall)

Plant spring-flowering bulbs.
Add new perennials, trees, and shrubs.
Divide and transplant overgrown perennials.
Plant cover crops in empty vegetable beds.

Step-by-Step: How to Plant Your Flowers Correctly

Good timing is half the battle. Proper planting ensures your flowers grow strong.

Prepare the Soil: Loosen the soil at least 12 inches deep. Mix in 2-3 inches of compost to improve drainage and nutrients.
Check Plant Needs: Read the tag for sun/shade requirements and spacing. Don’t crowd them; they need air flow.
Dig the Right Hole: For potted plants, make the hole twice as wide as the pot but no deeper.
Plant at the Correct Depth: The top of the root ball should be level with the soil surface. For bare-root plants, spread the roots gently.
Water Deeply: Soak the soil thoroughly after planting to settle it and eliminate air pockets.
Add Mulch: Apply 2-3 inches of mulch around plants, keeping it away from stems to prevent rot.

Choosing the Right Flowers for Pennsylvania

Selecting plants suited to our climate makes gardening easier. Here are some reliable performers.

Easy Annuals for Sun: Zinnias, Marigolds, Sunflowers, Cosmos. They love heat and bloom all summer.

Annuals for Shade: Impatiens, Begonias, Coleus. They add color to darker garden spots.

Low-Maintenance Perennials: Coneflower, Black-eyed Susan, Sedum, Daylily. They come back yearly with little fuss.

Native Plants: Butterfly weed, Bee balm, Cardinal flower. They support local wildlife and are very adaptable.

Common Mistakes to Avoid

Even experienced gardeners can make these errors. Being aware helps you sidestep them.

Planting Too Early: Patience is key. Tender plants hit by frost may never recover fully.
Ignoring Soil Health: Poor soil equals poor plants. Test your soil and amend it with organic matter.
Overcrowding: It leads to competition for light and water, and increases disease risk.
Incorrect Watering: Water deeply but less frequently to encourage strong roots. Avoid light, daily sprinkles.
Skipping Mulch: Mulch retains soil moisture, keeps roots cool, and reduces weeding.

FAQ: Pennsylvania Flower Planting

What month do you plant flowers in Pennsylvania?
It depends. You can plant hardy flowers in April, but most summer annuals should wait until May. Fall planting for bulbs and perennials is best in September and October.

When should I start planting in spring in PA?
Start seeds indoors in March. Begin planting cold-tolerant plants outdoors in April once the soil is workable. Wait until after your last frost date (often mid-to-late May) for tender plants.

Is it better to plant flowers in spring or fall in PA?
Both are excellent. Spring is for annuals and tender plants. Fall is ideal for perennials, shrubs, trees, and spring bulbs because the warm soil promotes root growth.

What are the best perennial flowers for Pennsylvania?
Choose hardy, reliable plants like coneflower, salvia, hosta, astilbe, and coreopsis. Always check that the perennial is rated for your USDA zone.

Can I plant flowers before the last frost?
Only hardy varieties like pansies, snapdragons, and certain seeds. For most summer flowers, it’s safest to wait until all danger of frost has past for your area.

By following these guidelines for when to plant flowers in PA, you give your garden the best foundation. Paying attention to the calendar and your local conditions leads to healthier plants and more blooms. Remember to keep a simple garden journal each year noting what you planted and when; it becomes an invaulable tool for planning future seasons.