Pennsylvania’s unpredictable frost dates make soil temperature your most reliable guide for planting dill. Finding the best time to plant dill in Pennsylvania depends more on your soil thermometer than the calendar. Dill is a cool-season herb that bolts quickly in heat, so timing matters.
Most gardeners aim for a spring planting after the last frost. But Pennsylvania spans zones 5a to 7b, so your exact window varies. This guide breaks down exactly when and how to plant dill for a steady harvest.
Best Time To Plant Dill In Pennsylvania
The best time to plant dill in Pennsylvania is early spring, as soon as the soil reaches 60°F (15°C). For most of the state, this falls between mid-April and early May. A second window opens in late summer for a fall harvest.
Dill is frost-tolerant once established, but seedlings are tender. Wait until the danger of hard frost passes. Use a soil thermometer to check at 2 inches deep. If the soil is still cold, hold off.
Spring Planting Window By Region
Pennsylvania’s climate varies widely. Here are general guidelines:
- Western PA (Pittsburgh area): Plant mid-April to early May
- Central PA (Harrisburg, State College): Plant late April to mid-May
- Eastern PA (Philadelphia, Allentown): Plant early to mid-April
- Northern PA (Erie, Scranton): Plant early to mid-May
- Southern PA (York, Lancaster): Plant early to mid-April
These are averages. Always check your local frost date. Dill seeds germinate best when soil is consistently 60–70°F. If you plant too early in cold, wet soil, seeds may rot.
Fall Planting For A Second Harvest
Dill grows well in cool fall weather. Plant a second crop in late summer for harvest before the first hard frost. Aim for 6–8 weeks before your average first frost date.
For most of Pennsylvania, this means planting from late July to mid-August. Fall dill often has better flavor because cool temps slow bolting. It also attracts fewer pests.
Understanding Pennsylvania’s Climate For Dill
Pennsylvania has a humid continental climate. Winters are cold, summers are warm and humid. Dill prefers cool weather and will bolt (flower and go to seed) quickly when temperatures stay above 85°F.
Spring and fall are ideal. Summer heat stresses dill, making leaves bitter. If you want fresh dill all season, you need to succession plant.
Frost Dates And Hardiness Zones
Pennsylvania spans USDA hardiness zones 5a to 7b. The last spring frost ranges from late April in the southeast to late May in the north. The first fall frost ranges from late September in the north to mid-October in the south.
Check your specific zip code for accurate dates. Dill can survive light frosts (28–32°F) once established. But young seedlings are damaged by hard freezes below 28°F.
Soil Temperature Is Key
Soil temperature matters more than air temperature. Dill seeds germinate poorly below 50°F. Optimal germination happens at 60–70°F. Use a soil thermometer to check.
To warm soil faster, cover planting beds with black plastic a week before planting. Remove it just before sowing. This can give you a 2-week head start in cooler regions.
Step-By-Step Guide To Planting Dill In Pennsylvania
Follow these steps for a successful dill crop. Dill is easy to grow if you get the basics right.
Step 1: Choose The Right Variety
Not all dill is the same. For leaves, choose ‘Bouquet’ or ‘Fernleaf’. For seeds, ‘Mammoth’ or ‘Long Island Mammoth’ work best. ‘Fernleaf’ is compact and good for containers.
Consider your goal. If you want dill for pickling, go with a tall variety. If you only need leaves for cooking, a dwarf variety works fine.
Step 2: Prepare The Soil
Dill likes well-drained, fertile soil with a pH of 5.5 to 6.5. Add compost or aged manure a week before planting. Dill has a taproot, so loosen soil to 12 inches deep.
Remove rocks and debris. Dill does not compete well with weeds, so clear the area thoroughly. Raised beds work well for drainage.
Step 3: Sow Seeds Correctly
Dill does not transplant well. Direct sow seeds in the garden. Plant seeds 1/4 inch deep and 6 inches apart in rows 12–18 inches apart. Cover lightly with soil.
Water gently after planting. Keep soil moist but not soggy. Seeds germinate in 7–14 days at 60°F. In cooler soil, it may take up to 21 days.
Step 4: Thin Seedlings
Once seedlings have 2–3 true leaves, thin them to 12 inches apart. Crowded dill produces fewer leaves and bolts faster. Thinning also improves air circulation.
You can eat the thinned seedlings. They taste like mild dill. Use them in salads or as garnish.
Step 5: Water And Mulch
Water dill consistently. Aim for 1 inch of water per week. Dill is somewhat drought-tolerant but grows best with regular moisture. Mulch with straw or grass clippings to keep soil cool.
Mulch also suppresses weeds. Dill’s shallow roots are easily damaged by hoeing. Mulch reduces the need for weeding.
Succession Planting For Continuous Harvest
Dill grows quickly and bolts in heat. To have fresh dill all season, plant every 2–3 weeks from spring through late summer. This is called succession planting.
Start your first planting in early spring. Then plant again in late spring, early summer, and late summer. Each planting gives you 4–6 weeks of harvest before bolting.
In hot summer months, choose a spot with afternoon shade. This slows bolting. You can also plant dill near taller crops like tomatoes or corn for natural shade.
Fall Succession Planting
For fall harvest, plant dill in late July and again in mid-August. Fall dill often has better flavor and lasts longer because temperatures are cooler. It also attracts fewer pests.
Cover fall dill with row covers if early frost threatens. Dill can survive light frosts, but hard freezes kill it. Harvest before temperatures drop below 25°F.
Common Mistakes When Planting Dill In Pennsylvania
Avoid these errors for a better harvest. Dill is forgiving, but certain mistakes reduce yield.
- Planting too early in cold, wet soil. Seeds rot instead of germinating.
- Planting too late in spring. Summer heat causes rapid bolting.
- Not thinning seedlings. Crowded dill is weak and bolts early.
- Overwatering. Dill hates soggy roots. Let soil dry slightly between waterings.
- Transplanting. Dill has a taproot and does not recover well from transplant shock.
- Ignoring pests. Aphids and parsleyworms love dill. Check plants weekly.
Dealing With Bolting
Bolting is when dill sends up a flower stalk. Leaves become bitter and tough. Bolting is triggered by heat and long days. You cannot stop it entirely, but you can delay it.
Plant dill in partial shade in summer. Keep soil consistently moist. Harvest leaves regularly to encourage bushier growth. Once flowers appear, let some go to seed for next year.
Harvesting Dill At The Right Time
Harvest dill leaves when the plant has at least 4–5 leaves. Pick outer leaves first, leaving inner ones to grow. For the best flavor, harvest in the morning after dew dries.
For dill seeds, wait until flower heads turn brown and seeds are firm. Cut the heads and hang them upside down in a paper bag. Seeds will fall out as they dry.
Dill leaves freeze well. Wash and dry them, then chop and freeze in ice cube trays with water or oil. Dill seeds store in an airtight container for up to a year.
How Much To Plant
For a family of four, plant 6–10 dill plants. If you want seeds for pickling or cooking, plant 12–15 plants. Dill self-sows easily, so you may get volunteers next year.
Dill also attracts beneficial insects like swallowtail butterflies and ladybugs. Plant extra if you want to support pollinators. The flowers are great for bees.
Growing Dill In Containers In Pennsylvania
If you have limited space, grow dill in containers. Choose a pot at least 12 inches deep and wide. Dill’s taproot needs depth. Use a dwarf variety like ‘Fernleaf’ for best results.
Fill the pot with well-draining potting mix. Sow seeds 1/4 inch deep and thin to 6 inches apart. Place the pot in full sun (6+ hours) but move to afternoon shade in summer heat.
Container dill needs more frequent watering. Check soil daily. Fertilize with a balanced liquid fertilizer every 2 weeks. Harvest leaves regularly to keep the plant compact.
Overwintering Dill
Dill is an annual. It dies after producing seeds. You cannot overwinter it outdoors in Pennsylvania. However, you can grow dill indoors in winter.
Use a south-facing window or grow lights. Sow seeds in a 12-inch pot. Keep soil moist and temperatures around 60–70°F. Harvest leaves as needed. Indoor dill is less productive but provides fresh flavor in winter.
Companion Planting With Dill
Dill is a great companion for many vegetables. It attracts beneficial insects and repels pests. Plant dill near cabbage, broccoli, onions, and lettuce. It improves their growth.
Avoid planting dill near carrots. They cross-pollinate and produce poor-quality seeds. Also keep dill away from tomatoes and peppers. Dill can stunt their growth.
Dill’s flowers attract parasitic wasps that control aphids and caterpillars. Plant dill near squash and cucumbers to reduce pest problems. The flowers also attract butterflies.
Pests And Diseases In Pennsylvania
Dill has few serious problems. Aphids are the most common pest. Spray them off with water or use insecticidal soap. Ladybugs and lacewings eat aphids naturally.
Parsleyworms (black swallowtail caterpillars) eat dill leaves. They are harmless to the plant and become beautiful butterflies. Leave them alone or move them to a sacrificial plant.
Dill can get powdery mildew in humid weather. Space plants for good air circulation. Water at the base, not on leaves. If mildew appears, remove affected leaves.
Frequently Asked Questions
Can I plant dill in Pennsylvania in July?
Yes, but it will bolt quickly in summer heat. Plant in partial shade and keep soil moist. For best results, wait until late July for a fall crop.
How late can I plant dill in Pennsylvania?
You can plant dill as late as mid-August for a fall harvest. Make sure you have at least 6–8 weeks before the first hard frost. Check your local frost date.
Does dill come back every year in Pennsylvania?
Dill is an annual. It dies after one season. However, it self-sows readily. If you let some plants go to seed, you will likely get volunteers next spring.
What is the best month to plant dill seeds in Pennsylvania?
April is the best month for most of Pennsylvania. Wait until soil reaches 60°F. In northern areas, May is better. In southern areas, late March or early April works.
Can I start dill indoors in Pennsylvania?
It is not recommended. Dill has a taproot and does not transplant well. Direct sow outdoors. If you must start indoors, use biodegradable pots and transplant carefully without disturbing roots.
Final Tips For Success
Dill is one of the easiest herbs to grow in Pennsylvania. Focus on soil temperature, not the calendar. Plant early for spring harvest and again in late summer for fall. Succession plant for a steady supply.
Harvest leaves before flowers appear for the best flavor. Let some plants go to seed for next year’s crop. Dill self-sows reliably, so you may never need to plant it again.
Remember that dill attracts beneficial insects. Plant extra if you want to support your garden’s ecosystem. The flowers are beautiful and fragrant.
With a little planning, you can enjoy fresh dill from spring through fall. Pennsylvania’s climate is perfect for this versatile herb. Just watch the soil temperature and plant at the right time.