How to Grow Potatoes in Pennsylvania

Growing potatoes in Pennsylvania involves one task most vegetables don’t require: hilling. You plant the seed pieces 4 inches deep, and then you keep mounding soil up around the stems as the plants grow, keeping developing tubers covered and away from sunlight. Skip that step and you get green, solanine-laced potatoes that are inedible. Do it right and you get a genuinely satisfying harvest — a buried treasure you dig up in late summer with a fork and a bucket.

PA Potato Growing Season

Quick Reference

Soil Prep & Site Selection

Sun & Site

Potatoes need full sun — at least 6 hours of direct sunlight daily. They also need good drainage. Potatoes sitting in waterlogged soil after heavy spring rains rot readily, and standing water during tuber development promotes late blight and other diseases. Avoid low spots that collect water after rain. If your garden soil stays wet for more than 24–48 hours after a heavy rain, build raised beds or plant on ridged rows to improve drainage.

Soil Type

Potatoes grow in a wider range of soils than most vegetables, but they do best in loose, well-drained, slightly acidic soil with good organic matter content. Pennsylvania’s predominant soil types — clay-heavy Piedmont in the east, rocky Ridge and Valley soils in the center, and more variable mixes in the west — all require some amendment for optimal potato production.

In heavy clay soils (common around Philadelphia, Harrisburg, and Allentown), work in 3–4 inches of compost and incorporate coarse sand or perlite to improve drainage and reduce compaction. Clay is the enemy of large, well-shaped potatoes — dense soil physically restricts tuber expansion and makes harvest difficult. In rocky soils, remove stones from the bed as much as practical; stones cause forking and irregular tuber shapes.

Soil pH

The ideal pH range for potatoes is 5.5–6.5. This is slightly more acidic than most vegetables prefer. Maintaining this range helps suppress common scab (Streptomyces scabies), which thrives in alkaline soil. If your soil has been limed in recent years (common in vegetable gardens targeting pH 6.8–7.0 for other crops), you may need to acidify slightly before planting potatoes. Sulfur amendments or acidifying fertilizers can lower pH over one to two seasons. Don’t try to lower pH dramatically in a single season.

Soil Preparation

Work the bed 10–12 inches deep to loosen soil for tuber development. Incorporate 2–4 inches of compost or well-aged manure across the entire planting area. Avoid fresh manure, which can promote scab. If using a fertilizer at bed preparation time, use one lower in nitrogen and higher in phosphorus — potatoes need P for root and tuber initiation, not just leafy green growth.

Choosing & Preparing Seed Potatoes

Always plant certified, disease-free seed potatoes. Don’t use supermarket potatoes — they’re often treated with sprout inhibitors and carry unknown disease histories. Certified seed potatoes are inspected for virus, ring rot, late blight, and other pathogens. Available from Johnny’s Selected Seeds, Fedco, High Mowing, and most local farm co-ops in Pennsylvania.

Cutting Seed Potatoes

Seed potatoes smaller than a golf ball can be planted whole. Larger ones should be cut into pieces, each with at least 2–3 eyes and weighing 1.5–2 oz (roughly egg-sized). Use a clean, sharp knife and cut just before planting or 24–48 hours in advance to allow the cut surface to callous. A calloused surface is dry and slightly corky — this reduces rot in cold, wet soils.

Chitting (Optional but Beneficial)

Chitting means pre-sprouting your seed potatoes in a cool, bright location 2–4 weeks before planting. Set them rose end up (the end with the most eyes) on a flat in a 50–60°F room with good light — not direct sun. Aim for sprouts 1/2 to 1 inch long. This speeds emergence by 7–14 days, which matters most in zone 5a where the growing window is tight.

Planting Depth, Spacing & Layout

Depth

Plant seed pieces 4 inches deep. Shallower planting means you’ll need more aggressive hilling to keep the developing tubers covered. Planting too deep (6+ inches) slows emergence in cold soils and reduces vigor.

In-Row Spacing

Space seed pieces 12 inches apart for small-to-medium varieties (Red Norland, Yukon Gold, fingerlings). Use 15 inches for larger varieties (Kennebec, Russet Burbank, Katahdin) that produce bigger plants and more lateral tuber spread. Crowded spacing reduces yield per plant and increases disease pressure by limiting air circulation.

Row Spacing

Space rows 24 inches apart at minimum; 30–36 inches is better. You will be hilling up soil from the row middles into the plant rows, so you need material to pull from. Tight rows make hilling difficult and result in inadequate coverage. With 36-inch rows you have plenty of material for three or four hilling sessions through the season.

Hilled Rows vs. Flat Beds vs. Raised Beds

Traditional hilled row planting is the most common method in Pennsylvania. Dig a trench 4 inches deep, place seed pieces, cover, and then hill up over the course of the season. Raised beds work well but require more effort during hilling — you’ll need to add soil or compost from outside the bed as plants grow. Tires, buckets, and wire cages filled progressively with soil or straw all work as container methods. I’ve grown potatoes in tires and in-ground rows — in-ground rows in well-amended soil consistently give the better yield.

Hilling: The Make-or-Break Task

Hilling is the defining task in potato growing. You’re mounding soil (or straw or compost) around the base of the plants to cover developing tubers and keep them away from light. Any tuber exposed to sunlight turns green, producing solanine — a mildly toxic compound that makes the potato bitter and potentially harmful in large quantities. Green potatoes should not be eaten.

When to Hill

Start the first hilling when plants are 6–8 inches tall. Pull soil from the row middles and mound it around the stem, leaving only 2–3 inches of foliage exposed. Repeat when plants have grown another 6–8 inches above the hill. Most growers do 2–3 hilling sessions per season, building the hill 8–12 inches tall by mid-summer.

What to Hill With

Soil pulled from the row middles is the standard approach. You can supplement with compost, loose straw, shredded leaves, or a mix. Pure straw hills dry out faster and provide less physical resistance for expanding tubers than soil, but they work and make harvest much easier — you can pull potatoes out by hand from a straw hill. Straw mulch also helps moderate soil temperature, which is beneficial during July heat.

After Hilling is Done

Once plants have flowered and foliage begins to mature (turn yellow and die back), stop hilling. The tubers are set and won’t grow larger regardless of additional soil coverage. Continued disturbance of the hill during this phase can damage developing tubers.

Watering Potatoes in Pennsylvania

Potatoes need consistent moisture — 1 to 2 inches of water per week from rain or irrigation, with consistent soil moisture throughout the growing season being more important than any single watering volume. Irregular watering (dry spells followed by heavy rain or irrigation) causes hollow heart, knobby deformities, and cracking.

Critical Moisture Periods

Two growth stages are particularly moisture-sensitive. The first is tuber initiation, which occurs when plants begin to flower — typically 4–8 weeks after planting. Drought stress during this period dramatically reduces tuber count. The second is tuber bulking (4–10 weeks after initiation), when existing tubers are enlarging. Drought during bulking reduces final tuber size.

Watering Method

Drip irrigation or soaker hoses are ideal for potatoes. Surface drip keeps foliage dry, reducing late blight pressure. Overhead sprinklers wet foliage and can spread spores during humid late-summer conditions — the classic PA blight setup. If overhead watering is all you have, water in the morning so foliage dries before evening.

Reducing Watering Toward Harvest

About 2 weeks before planned harvest, stop irrigation to allow the skin to set. Thin-skinned potatoes (Red Norland, new Yukon Golds) don’t need extended curing, but potatoes destined for long-term storage need firm, set skin. Wet soil at harvest also makes the potatoes more difficult to cure and store properly.

Fertilizing for Tuber Development

Pre-Plant Fertilizing

Incorporate a balanced fertilizer or compost into the bed at preparation. A soil test is the most reliable guide — the Penn State Extension soil testing lab is the standard resource for Pennsylvania gardeners. Without a test, assume you need moderate phosphorus and potassium. Excess nitrogen at planting produces lush green vines at the expense of tuber development — a common mistake.

Nitrogen Management

Potatoes need enough nitrogen for healthy vine growth through flowering, then a shift toward potassium-driven tuber development. Apply a moderate nitrogen fertilizer (balanced 10-10-10 or similar) at planting or as a side-dress when plants are 8 inches tall. Once plants are flowering and tubers are setting, stop nitrogen applications. Adding nitrogen during tuber bulking pushes vines rather than tubers and delays maturity.

Potassium

Potassium is the most important nutrient for tuber quality — yield, density, cooking quality, and storage life all depend on adequate K. Pennsylvania soils are often moderate to adequate in potassium, but heavy yields can deplete it. If your soil test shows low potassium, side-dress with potassium sulfate (not potassium chloride/muriate of potash, which promotes scab) when plants are at the flowering stage.

Calcium & pH

Calcium deficiencies can cause internal browning and hollow heart. Calcium availability is directly tied to soil pH and consistent moisture — drought stress reduces calcium uptake even in soils with adequate calcium levels. Don’t add lime to potato beds (it raises pH and promotes scab), but keep soil evenly moist during tuber development to optimize calcium uptake.

Pests & Disease

Colorado Potato Beetle

The Colorado potato beetle (Leptinotarsa decemlineata) is the most destructive insect pest of potatoes in Pennsylvania, and it will find your plants. Adults overwinter in the soil and emerge in spring around the same time potato plants are establishing. The yellow-and-black striped adults lay orange egg clusters on the undersides of leaves; the reddish, humpbacked larvae that hatch feed aggressively and can completely defoliate plants.

Scout weekly starting from emergence. Look for egg masses on leaf undersides and crush them. Hand-pick adults and larvae into a bucket of soapy water. For larger plantings, spinosad (organic, effective) or pyrethrin (organic) applied in the evening controls larvae. Neem oil is less effective on this pest. Conventional gardeners can use imidacloprid as a soil drench at planting, but this systemic insecticide affects pollinators and should not be used where potato flowers will be accessible to bees.

Potato Leafhopper

Potato leafhoppers (Empoasca fabae) migrate north into Pennsylvania from overwinter areas in the south, arriving in late May to early June. They inject a toxin while feeding that causes “hopperburn” — leaf margins turn yellow, then brown, and the plant looks drought-stressed even when soil moisture is adequate. A bad leafhopper year significantly reduces yield. Yellow sticky traps help monitor arrival; kaolin clay sprays deter feeding; pyrethrin or spinosad can control heavy infestations.

Aphids

Several aphid species feed on potato vines. Beyond direct feeding damage, aphids transmit potato virus Y (PVY) and potato leafroll virus (PLRV), which can severely reduce yield in infected plants and contaminate seed potatoes for next year. Reflective mulch deters landing aphids. Insecticidal soap works for heavy infestations. Natural enemies (lacewings, parasitic wasps, lady beetles) provide good control in most seasons — avoid broad-spectrum insecticides that kill beneficials.

Wireworms

Wireworm larvae (click beetle larvae) tunnel into developing tubers, creating holes that reduce marketability and provide entry points for rot organisms. They’re most problematic in soils that were previously sod or cover crops. Damage shows up at harvest. There’s no effective organic control once they’re in the soil; crop rotation away from potatoes for 3+ years and avoiding planting in recently converted sod are the practical management approaches.

Late Blight (Phytophthora infestans)

Late blight is the same organism that caused the Irish potato famine and that regularly devastates both tomatoes and potatoes in Pennsylvania. It thrives in the cool, humid conditions of PA’s late summer — nights below 65°F with daytime humidity above 80% create the perfect spread conditions. Infected plants show water-soaked gray-green lesions on leaves that quickly turn brown and papery; infected tubers have firm, dark, reddish-brown internal rot.

Prevention is the only practical strategy. Plant resistant varieties (Kennebec, Elba). Avoid overhead watering. Space plants for air circulation. Remove and destroy (don’t compost) any infected plant material immediately. Copper-based fungicides (copper sulfate, copper hydroxide) applied preventively starting in mid-July when conditions favor blight can slow its spread. Organic growers should apply copper on a 7–10 day schedule when humidity is high; conventional gardeners can use mancozeb or chlorothalonil.

Early Blight (Alternaria solani)

Early blight causes brown, target-like concentric rings on older leaves, typically starting from the bottom of the plant and working upward. It’s common in Pennsylvania but less devastating than late blight. It’s primarily a stress disease — plants under nutrient, water, or heat stress are far more susceptible. Maintain adequate potassium, consistent moisture, and good air circulation. Copper fungicides help. Unlike late blight, early blight doesn’t rot tubers.

Common Scab (Streptomyces scabies)

Scab causes rough, corky, raised or sunken patches on potato skin. The potatoes are still edible — scab doesn’t penetrate deep into the flesh — but they look poor and are harder to wash and store. Scab thrives at soil pH above 6.5, in dry soils, and with fresh manure. Control: keep soil pH between 5.5 and 6.5, maintain consistent moisture during tuber development, avoid fresh manure, and use scab-resistant varieties (Chieftain, Elba, Norland). Never lime a potato bed.

Harvest, Curing & Storage

New Potatoes

New potatoes can be harvested as soon as tubers reach a usable size — typically 60–70 days after planting for early varieties. They have thin, delicate skin and should be eaten within a few days. Reach into the hill and feel around for marble-to-golf-ball-sized tubers without disturbing the rest of the plant; the plant will continue producing the main crop.

Main Crop Harvest

Harvest the main crop when the vines die back naturally — yellow foliage, collapsing stems. For most mid-season varieties in Pennsylvania, this means late August through September. Late-season types like Katahdin and Russet Burbank may not die back until October. If a frost threatens before vines have died back naturally, cut the vines at ground level; the tubers will continue to skin-set in the soil for 2 weeks before harvest.

Dig potatoes when soil is dry. Use a garden fork placed 8–12 inches away from the plant center to avoid spearing tubers. Lift the plant, then comb through the loosened soil to find all tubers. Missing potatoes left in the soil will volunteer next spring and can harbor disease. On a good day in amended soil, digging potatoes is satisfying. On a wet day in clay, it’s a chore — plan accordingly.

Curing

Cure harvested potatoes for 10–14 days at 50–60°F with high humidity (85–95%) and good ventilation before moving to long-term storage. Curing heals minor skin cuts and scratches, toughens the skin, and allows any surface moisture to dry. Uncured potatoes go soft and rot much faster in storage. A basement, root cellar, or cool garage works well. Spread potatoes in a single layer or shallow boxes — don’t pile them deep during curing.

Long-Term Storage

After curing, move potatoes to a cool (38–40°F), dark, well-ventilated location. Temperatures below 38°F convert potato starch to sugars (making them overly sweet and prone to browning when fried). Temperatures above 50°F cause premature sprouting. High humidity (85–90%) prevents shriveling; low humidity causes moisture loss. Under ideal conditions, mid- and late-season varieties (Kennebec, Katahdin, Russet Burbank) will keep 5–6 months. Early varieties (Red Norland, Yukon Gold) store 2–4 months at best.

Zone-Specific Growing Notes

Select your zone to highlight the information most relevant to your growing conditions.

Full-Season Task Schedule

Frequently Asked Questions About Growing Potatoes in Pennsylvania

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