Herb

When to Plant Basil in Pennsylvania

The king of herbs. Basil and tomatoes are best friends in the garden and in the kitchen.

The Short Answer

Pennsylvania basil season stretches from late May through the first frost in October — a solid 4-5 month window in most of the state. The southeastern counties around Philadelphia enjoy the longest season, while the Poconos and northern tier work with a more compressed window. Pennsylvania's Italian-American communities have a deep tradition of growing Genovese basil for fresh pesto, and September basil harvests for freezing are a ritual in many families.

Pennsylvania Frost Dates

Your planting dates depend on which part of Pennsylvania you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Northern Pennsylvania 5a, 5b, 6a May 5 - May 20 Sep 20 - Oct 5
Central Pennsylvania 5b, 6a, 6b Apr 25 - May 10 Oct 1 - Oct 15
Philadelphia Region 7a, 7b Apr 5 - Apr 20 Oct 15 - Nov 5

Basil Planting Schedule for Pennsylvania

Northern Pennsylvania (Zones 5a, 5b, 6a)

Average last frost: May 5 - May 20 · Average first frost: Sep 20 - Oct 5

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Central Pennsylvania (Zones 5b, 6a, 6b)

Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Philadelphia Region (Zones 7a, 7b)

Average last frost: Apr 5 - Apr 20 · Average first frost: Oct 15 - Nov 5

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Growing Basil in Pennsylvania

State-Specific Growing Tips

Start seeds indoors in early April. Transplant outside in late May (southeastern PA) to early June (northern PA) after nights consistently exceed 50°F. Pennsylvania's humid summers can promote disease, so space plants 12-15 inches apart for air circulation. Pinch flower buds every few days. For the big fall pesto harvest, let plants grow unpinched through September, then harvest entire plants before the first frost — strip all leaves and freeze in olive oil in ice cube trays for year-round pesto.

Recommended Varieties for Pennsylvania

Genovese is the Pennsylvania standard. Nufar offers some downy mildew tolerance with good flavor. Prospera and Devotion for strong disease resistance. For variety, Thai Basil handles the humid Pennsylvania summer well. Lemon Basil is popular for fish dishes and cocktails. Penn State Extension provides variety recommendations in their herb growing guides.

Common Challenges in Pennsylvania

Downy mildew arrived in Pennsylvania in 2009 and is now an annual concern. Resistant varieties are the strongest defense. Japanese beetles arrive in June-July and feed heavily on basil. Cool, wet springs can cause damping off in seedlings. In the northern tier, the short season means any pest or disease setback has a disproportionate impact on total harvest.

Growing Tips

Pinch off flower buds to keep leaves producing. Harvest from the top down, cutting just above a leaf pair. Succession plant for season-long supply.

Companion Planting

Plant basil alongside these companions for better growth:

Tomatoes Peppers Oregano

Keep basil away from:

Sage

The Bottom Line

Basil can be grown successfully in Pennsylvania with proper attention to regional frost dates and local growing conditions. Timing varies across the state — Northern Pennsylvania gardeners work with a last frost around May 5 - May 20, while Philadelphia Region sees frost end around Apr 5 - Apr 20. Choose varieties suited to your region, amend your soil based on its specific needs, and monitor for the pests and diseases most common in your area. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Basil Growing Guide National planting guide with all states Pennsylvania Planting Calendar All plants for Pennsylvania Basil in Alabama Alabama planting dates Basil in Alaska Alaska planting dates Basil in Arizona Arizona planting dates Basil in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

Ready to Start Planting?

Enter your zip code and pick your plant. We'll tell you exactly when to plant, start seeds, and harvest — based on where you live.

Find Your Planting Dates