What to Plant in May in Pennsylvania

May is the month Pennsylvania gardeners wait all year for. The frost risk finally drops off, soil temps climb into the 60s and 70s, and every warm-season crop you’ve been babying under grow lights can go outside. If you only garden one month of the year, this would be it — but please don’t do that, because there’s great planting to do all season long.

Here’s the thing about May in PA, though: the state is big enough that early May in Philadelphia and early May in Scranton are practically different seasons. Zone 7a gardeners are transplanting tomatoes the first week while zone 5b gardeners are still watching for frost warnings. Know your zone, check your local frost dates, and you’ll be fine.

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When to Transplant the Big Three: Tomatoes, Peppers, and Eggplant

This is the main event. The crops everyone asks about, the ones that define a PA summer garden, and the ones that need the right timing more than anything else you’ll grow.

Tomatoes

Tomatoes need nighttime temps consistently above 50°F and soil temps above 60°F. In most of PA, that means mid-May is your safe transplant window. Zone 7a gardeners can push to early May. Zone 5b and mountain gardeners should target the last week of May or even early June.

Your Zone	Last Frost (avg)	Safe Tomato Transplant
7a (Philly)	March 30	Early May
6b (Reading, York)	April 12–14	May 10–15
6a (Pittsburgh, Harrisburg)	April 10–20	May 10–20
5b (Scranton, Erie)	April 24 – May 1	May 20–30
5a (Mountains)	May 1–10	Late May – early June

Plant tomatoes deep — bury two-thirds of the stem. Tomatoes grow roots all along the buried stem, which creates a stronger, more drought-resistant plant. Dig a deep hole or a trench and lay the stem sideways with just the top few leaf sets above ground.

Space indeterminate varieties 24–36 inches apart and stake or cage them at planting. Don’t wait until they’re flopping over — getting the cage on early saves you from wrestling a tangled 5-foot plant in July.

Peppers

Peppers are even less cold-tolerant than tomatoes. They stall in cool soil and won’t recover their momentum if they get chilled early. Wait until nighttime temps are reliably above 55°F — that’s usually a week after your safe tomato date. For most of PA, that means mid-to-late May.

Space sweet peppers 18 inches apart, hot peppers 12–15 inches. Peppers don’t need to be planted deep — set them at the same depth they were in the pot. Mulch around the base to keep soil warm and conserve moisture.

Eggplant

Eggplant wants the warmest conditions of the three. It’s originally a tropical plant and absolutely hates cool nights. Wait until nighttime temps are consistently above 55°F. Plant 18–24 inches apart. Eggplant in PA benefits from black plastic mulch to warm the soil, especially in zones 5b and 6a.

What to Direct Sow Outdoors in May

Beans (Bush and Pole)

Beans need soil temps above 60°F to germinate without rotting. Plant 1 inch deep, 3–4 inches apart for bush beans, 4–6 for pole beans. Don’t start indoors — they transplant poorly and germinate fast in warm soil. Succession plant bush beans every two weeks through end of June.

Corn

Corn needs warm soil and plenty of space. Plant in blocks of at least 4 rows — corn is wind-pollinated and needs neighboring plants. Sow 1 inch deep, 8–12 inches apart, rows 30–36 inches apart. Corn is a heavy feeder that especially loves nitrogen.

Cucumbers

Cucumbers go from seed to harvest in 50–70 days, making mid-May sowing ideal even for zone 6a. Plant seeds 1 inch deep, 12 inches apart for trellised plants or 36 inches for ground spreaders. Trellising improves air circulation and reduces powdery mildew.

Squash and Pumpkins

Summer squash matures fast — 45–55 days — and produces so aggressively that two plants can overwhelm a family of four. Winter squash and pumpkins need 80–120 days and a lot more space. Plant in hills 4–6 feet apart.

Melons

Watermelons and cantaloupes need the warmest soil and longest season. Short-season varieties are your best bet in PA. Sugar Baby watermelon (80 days) and Minnesota Midget cantaloupe (65 days) mature reliably even in zone 6a.

Herbs

May is when you can finally plant the warm-season herbs outdoors: basil (frost-sensitive — plant after all frost risk), dill (direct sow, doesn’t transplant), and cilantro (succession plant every 3 weeks for continuous supply). Perennial herbs like rosemary, thyme, oregano, and sage can be transplanted outdoors in May too.

Succession Planting: Keep the Spring Crops Going

• Lettuce — sow every 10–14 days through mid-May. Switch to heat-tolerant varieties as temps climb.
• Radishes — keep sowing until mid-May. They’ll bolt in June heat — this is your last window until fall.
• Beets and carrots — sow another round in early May for a June/July harvest.

Container Planting

Everything that goes in the ground in May can go in containers. Tomatoes need minimum 5-gallon pots, peppers work great in 3-to-5-gallon containers, and most herbs do fine in 1-to-3-gallon pots. Container plants may need watering every day during PA’s hot summer stretches.

Soil and Planting Tips for May

Soil Temperature Check

Don’t trust the air temperature — check the soil. Insert a thermometer 4 inches deep in the morning. You’re looking for: 50°F for tomatoes to survive, 60°F for beans/corn/cucumbers/squash, 65°F+ for melons/peppers/eggplant.

Mulching

After transplanting, wait 1–2 weeks before mulching so the soil can warm up. Then apply 2–3 inches of straw, shredded leaves, or wood chips around (not touching) the stems.

Watering at Transplant

Give every transplant a thorough soaking at planting time, then ease off to 1 inch per week. Overwatering new transplants encourages shallow root growth and can cause root rot, especially in PA’s clay soils.

May Planting Calendar at a Glance

Task	Zone 5a–5b	Zone 6a	Zone 6b	Zone 7a
Transplant tomatoes	Late May – early June	May 10–20	May 10–15	Early May
Transplant peppers/eggplant	Late May – June	May 15–25	May 15–20	Mid-May
Direct sow beans	Late May	Mid-May	Mid-May	Early May
Direct sow corn	Late May	Mid-May	Mid-May	Early May
Direct sow cucumbers/squash	Late May	Mid-May	Mid-May	Early–mid May
Plant basil and warm herbs	After last frost	Mid-May	Mid-May	Early May
Last lettuce/radish sowing	Early May	Early–mid May	Early–mid May	Already done

FAQ

When can I plant tomatoes outside in Pennsylvania? After your last frost date when nighttime temps stay above 50°F and soil hits 60°F. For most of PA (zones 6a–6b), that’s mid-May. Zone 7a (Philly) can go early May. Zone 5b should wait until late May or early June.

What vegetables should I plant in May in PA? May is when you plant everything warm: tomatoes, peppers, eggplant, beans, corn, cucumbers, squash, pumpkins, and melons. Plant warm herbs like basil, dill, and cilantro.

Can I plant tomatoes on May 1 in Pennsylvania? Only in zone 7a (Philadelphia area) — and even then, keep an eye on the forecast. For the rest of PA, May 1 is too early.

What should I NOT plant in May in Pennsylvania? Don’t start new cool-season crops (peas, spinach) after mid-May — they’ll bolt. And don’t plant garlic — that’s a fall crop. Everything else is fair game.

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