When to Plant Potatoes in Pennsylvania
Plant potatoes in Pennsylvania when soil temperature reaches 45°F at a 4-inch depth — typically late February in zone 7a Philadelphia suburbs and as late as early May in zone 5a northern highland counties. The hard rule isn’t the calendar date; it’s the soil. Frozen ground won’t let you plant regardless of the date, and soil below 40°F will rot seed pieces before they can sprout.
Table of Contents
PA Potato Planting Season
Pennsylvania’s potato planting calendar stretches from late February in the warmest southeastern zones to the first weeks of May in the northern highlands. The growing season itself runs through summer, with harvest beginning for early varieties in July and extending through October for main-season storage crops.
Main spring planting window
Growing & hilling (second crop planting late Jun–Jul)
Harvest
Quick Reference by Zone
Soil Temperature Requirements
The minimum soil temperature for planting potatoes is 45°F at 4-inch depth. Below that, seed pieces sit in cold, wet soil and risk rotting before the eyes can sprout. The optimal planting range is 50–65°F — germination is faster, more uniform, and the plants establish more vigorously.
You can check soil temperature with a simple probe thermometer. Take the reading at 4 inches in mid-morning, after the soil has had a chance to warm slightly from overnight temperatures. A single reading on a sunny day after a warm week can be misleading — take readings on three or four consecutive days to confirm the trend.
Potatoes can tolerate a light frost after they emerge — the young foliage may get nipped, but the plant usually recovers from the soil. A hard frost (28°F or below) on emerged plants is more damaging. The seed piece underground is fine; the tops will re-sprout but you lose 2–3 weeks of growth. This is why planting slightly early is a reasonable risk that experienced PA growers take, particularly for early-season varieties.
Spring Planting Windows by Zone
Zone 7a — Philadelphia Metro, Chester County, Delaware County
Plant late February through mid-March. Last average frost is around March 25–April 5, but soil temperature reaches 45°F in late February in most years. Zone 7a is the only part of Pennsylvania where potatoes regularly go in the ground in February. By planting this early, you can harvest early varieties (Red Norland, Yukon Gold) before summer heat arrives and reduce the mid-July to August late blight pressure window.
Zone 7a: Spring plant Feb–Mar · 2nd crop Jul · Harvest Aug–Sep
Zone 6b — Harrisburg, Lancaster, Allentown, Reading
Plant mid-March through early April. Last average frost falls around April 15–20, but soil temperature in protected, south-facing beds can hit 45°F by mid-March. Most zone 6b growers target late March as their standard planting date. This is a comfortable zone for mid-season varieties like Kennebec and fingerlings — you have the full 90–110 day window without rushing.
Zone 6b: Spring plant Mar–Apr · 2nd crop Jul · Harvest Aug–Oct
Zone 6a — Pittsburgh, State College, Scranton, Erie
Plant early April through late April. Last average frost is May 1–10 depending on exact location, but soil temperatures reach 45°F in late March to early April. Pittsburgh area growers can plant a week or two earlier than Scranton or Erie due to the urban heat island effect and slightly different microclimates. Zone 6a is well-suited for mid-season varieties and Katahdin at 100–120 days typically finishes before the first fall frost.
Zone 6a: Spring plant Apr · 2nd crop Jul · Harvest Aug–Oct
Zone 5b — Northern Mountains, High Ridge Areas
Plant mid-April through May 1. Last average frost runs May 10–20 in most zone 5b locations. Soil temperature is the limiting factor — in shaded or north-facing sites, soil may not reach 45°F until late April. Stick with early and early-mid season varieties (Red Norland, Yukon Gold, Chieftain) that finish in under 100 days. A late-season russet planted in late April may not bulk up before September frosts arrive.
Zone 5a — Northern Tier Counties, Pocono Highlands
Plant late April through May 10. Last average frost reaches into mid-to-late May in the highest elevations. In zone 5a, the summer growing window is compressed — roughly 120 days between frosts, which means varieties with over 100-day maturity are marginal at best. Red Norland at 70–80 days is the reliable choice. Yukon Gold at 80–90 days usually works. Don’t plant fingerlings that require 90–100 days unless you have a confirmed warm microsite.
Planting Dates by City
Select your zone to highlight your region’s window, or reference the table directly for city-specific dates.
| City / Region | Zone | Avg Last Frost | Plant Spring Potatoes | Harvest Window |
|---|---|---|---|---|
| Philadelphia | 7a | Mar 28 | Feb 20 – Mar 15 | Jul – Sep |
| Chester / Delaware Co. | 7a | Apr 2 | Feb 25 – Mar 20 | Jul – Sep |
| Lancaster | 6b | Apr 15 | Mar 15 – Apr 5 | Aug – Oct |
| Harrisburg | 6b | Apr 17 | Mar 15 – Apr 5 | Aug – Oct |
| Allentown | 6b | Apr 20 | Mar 20 – Apr 10 | Aug – Oct |
| Reading | 6b | Apr 18 | Mar 18 – Apr 8 | Aug – Oct |
| Pittsburgh | 6a | Apr 30 | Apr 1 – Apr 20 | Aug – Oct |
| State College | 6a | May 5 | Apr 5 – Apr 22 | Aug – Oct |
| Scranton / Wilkes-Barre | 6a | May 1 | Apr 3 – Apr 20 | Aug – Oct |
| Erie | 6a | May 5 | Apr 5 – Apr 25 | Aug – Oct |
| Williamsport | 5b | May 10 | Apr 15 – May 1 | Aug – Oct |
| Wellsboro / Northern Tier | 5a | May 20 | Apr 25 – May 10 | Aug – Sep |
Second Crop: Planting for Fall Harvest
Pennsylvania’s growing season in zones 6a and warmer is long enough to support a second potato planting for fall harvest. This is different from letting a spring crop grow all season — it’s a dedicated late-summer planting designed to produce new potatoes in September and October.
The math: count back 90–100 days from your first fall frost date. In zone 6b (Harrisburg, Lancaster), first fall frost typically arrives around October 15–25, so count back 90 days and you land on late June to mid-July as the second-crop planting window. In zone 7a (Philadelphia), with frosts not arriving until late October or November, you can plant as late as mid-July and still get a full early-season variety to finish.
The challenge with second-crop potatoes in PA is summer heat. Potatoes set tubers best when nighttime temperatures are below 70°F. Planting in late June or July means the plants are establishing during the hottest weeks of the year. Mulch heavily (4–6 inches of straw) to keep soil temperatures cooler, and water consistently — heat stress during tuber initiation produces small, irregular potatoes.
Zone 5a and 5b growers generally can’t pull off a second crop reliably. The spring season is compressed, the summer window is short, and early fall frosts arrive before a second crop could mature.
Preparing Your Seed Potatoes
Chitting (Pre-Sprouting)
Chitting means letting your seed potatoes develop short, sturdy sprouts before planting. Set them in a single layer in a cool (50–60°F), bright location — not direct sunlight — two to four weeks before your planting date. The goal is sprouts 1/2 to 1 inch long. Longer, pale, spindly sprouts indicate too much warmth or too little light and will break off during planting.
Chitting isn’t strictly necessary, but it speeds up emergence by 1–2 weeks — a meaningful advantage in zone 5a where you’re trying to maximize every growing day. In zone 7a with a long season, chitting is optional.
Cutting Seed Potatoes
Small seed potatoes (golf ball size or smaller) can be planted whole. Larger pieces should be cut so each piece has 2–3 eyes and weighs at least 1.5–2 oz — roughly the size of a large egg. Cut pieces with a clean, sharp knife and allow cut surfaces to callous for 24–48 hours before planting. Callousing reduces the risk of rot in cold, wet spring soils. Dusting cut pieces with agricultural sulfur or wood ash can help further in wet springs.
Seed Potato Storage Before Planting
Store seed potatoes in a cool (38–45°F), dark, well-ventilated location until planting time. Don’t leave them in a warm garage or sunny spot — they’ll sprout prematurely and exhaust their energy reserves. If you order seed potatoes early and need to hold them for several weeks, keep them in paper bags (not plastic) in a root cellar, cool basement, or refrigerator set above 38°F.
Zone-Specific Planting Notes
Select your zone to highlight the information most relevant to your region.
| Zone | Spring Plant Window | Second Crop | Key Considerations |
|---|---|---|---|
| 5a | Apr 25 – May 10 | Not reliable | Use only early varieties (<90 days); avoid late-season types; compressed window of ~120 days between frosts |
| 5b | Apr 15 – May 1 | Marginal | Early and early-mid varieties only; soil temp is the bottleneck — check before planting even if calendar says “go” |
| 6a | Apr 1 – Apr 20 | Possible Jul 1–15 | Full mid-season range available; Katahdin at 100–120 days finishes in most years; second crop risky in Erie and high elevations |
| 6b | Mar 20 – Apr 10 | Jun 25 – Jul 10 | Good zone for fingerlings and storage varieties; blight pressure increases Jul–Aug so favor resistant varieties |
| 7a | Feb 20 – Mar 15 | Jul 1 – Jul 20 | Earliest planting in PA; spring drought can be an issue Feb–Mar; summer blight pressure is real — plant Kennebec or Elba for storage |
Plan your full season: Check our month-by-month Pennsylvania planting guide to see what else to plant from our Pennsylvania vegetables collection alongside potatoes throughout the year.
Frequently Asked Questions About Planting Potatoes in Pennsylvania
Can I plant potatoes before the last frost in Pennsylvania?
Yes. Potatoes are planted 2–4 weeks before the last expected frost in most PA growing guides, as long as soil temperature is above 40–45°F. The seed pieces underground are protected from frost, and emerged foliage can usually survive light frosts (32–28°F). A hard frost (below 28°F) on emerged plants will kill the tops but the plant will usually resprout from the soil — you lose 2–3 weeks of growth but not the crop. In zone 7a, growers routinely plant in late February well before the last frost date.
What happens if I plant potatoes too early in Pennsylvania?
Planting in soil below 40°F dramatically increases the risk of seed piece rot. Cold, wet soil lacks the microbial and enzymatic activity needed to support healthy sprout development, and the cut surfaces of seed potatoes become vulnerable to fungi and bacteria. You may plant what looks like a healthy seed piece and find nothing but mush two weeks later. The fix is patience — check soil temperature at 4-inch depth and wait for at least 45°F across multiple consecutive days before planting.
What happens if I plant potatoes too late in Pennsylvania?
Late planting pushes tuber development into the hottest part of summer, which reduces yield. Potatoes form tubers best when nighttime temperatures are below 70°F — a threshold that Pennsylvania consistently breaks in July and August. A mid-May planting in zone 6a means tuber initiation coincides with the heat of June and July, resulting in smaller, fewer tubers. Zone 5a growers who wait until mid-May also risk having late-season varieties cut down by an early September frost before they finish. Plant as early as soil conditions allow.
How do I know when Pennsylvania soil is warm enough to plant potatoes?
Use a probe thermometer inserted 4 inches into the soil. Take readings in mid-morning (not after a sunny afternoon when surface readings are inflated) and track them for 3–5 consecutive days. You’re looking for a consistent reading of 45°F or above. If you don’t have a soil thermometer, a rough field test: push your hand 4 inches into bare soil. If it feels painfully cold and you can’t hold it there for 10 seconds, it’s too early. If it feels cool but tolerable, check with a thermometer to be sure.
Can I grow a second crop of potatoes in Pennsylvania for fall harvest?
In zones 6a and warmer, yes. The second crop requires 90 days minimum, so count back from your expected first fall frost. In zone 6b (Harrisburg, Lancaster), that means planting late June to early July. In zone 7a (Philadelphia), you have until mid-July. Use only early-maturing varieties (Red Norland, Yukon Gold at 70–90 days) — mid-season types won’t finish in time. The challenge is heat: July-planted potatoes establish during PA’s hottest weeks. Mulch heavily and water consistently to manage soil temperature during tuber set.
How long does it take for potatoes to sprout after planting in Pennsylvania?
In warm soil (55–65°F), chitted potato pieces typically emerge in 14–21 days. In cool soil (45–50°F), expect 3–4 weeks or slightly longer. If you haven’t seen any growth after 5 weeks in reasonable soil conditions, the seed pieces may have rotted — scratch carefully around where you planted and check. Un-chitted potatoes take longer than chitted ones; starting with sprouted seed potatoes can shave a week or more off the emergence time, which matters in zone 5a where the season is tight.
