Growing Potatoes: Hilling, Blight & Variety Guide

title: "Growing Potatoes: Complete Garden Guide"

—- title: "Growing Potatoes: Complete Garden Guide" slug: growing-potatoes hub: vegetables category: Vegetable description: "How to grow potatoes from seed potatoes: chitting, planting depth, hilling, variety selection, and managing late blight and scab. Extension-sourced." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 10 —-

I don't grow potatoes at my Long Island plot — the space requirement and the management of late blight in the humid Northeast makes them a lower priority than the tomatoes and peppers I do grow. This guide is sourced from Cornell Cooperative Extension, Penn State Extension, and the USDA, which publish the most thorough guidance on home potato production for the mid-Atlantic and Northeast.

Potato growing is straightforward in concept: plant a piece of potato, hill soil around the emerging plants repeatedly, harvest in summer or fall. The complications arise from disease — specifically late blight (Phytophthora infestans), the same pathogen that affects tomatoes — and from understanding how tuber formation works well enough to support it through hilling and irrigation.

Variety selection

Solanum tuberosum cultivars are classified by skin color, flesh color, and maturity:

Early season (55—70 days from planting): 'Yukon Gold' (yellow flesh, excellent flavor), 'Red Norland' (red skin, white flesh, good boiled). Per Cornell Cooperative Extension, early varieties are ready before the peak late blight season in the Northeast and are useful for areas with high disease pressure.

Midseason (70—90 days): 'Kennebec' (white, disease-tolerant, widely grown), 'Red Pontiac' (red skin, good yield), 'Adirondack Blue' (purple skin and flesh). 'Kennebec' has \"good tolerance to late blight\" per Penn State Extension and is the recommended all-purpose variety for the Northeast.

Late season (90—120 days): 'Russet Burbank' (the classic baked potato), 'Katahdin' (white, good disease resistance), 'Elba' (excellent late blight tolerance per Cornell). Late varieties produce the largest yields but require a longer growing season and greater disease management.

Per Johnny's Selected Seeds, days-to-maturity figures for potatoes are highly variable and depend on soil temperature, growing conditions, and whether early tubers or full storage-size tubers are the goal.

USDA zones and temperature requirements

Potatoes are grown as annuals across USDA zones 3—10, with timing adjusted for climate. Per Cornell Cooperative Extension, potatoes grow best at air temperatures of 60—70°F and require soil temperatures of at least 45—50°F for planting.

Per Penn State Extension, plant seed potatoes 2—4 weeks before the last expected frost, once soil has reached 45°F. Tubers can withstand light frost, but frost that kills foliage sets the plant back significantly. In zone 7a (Long Island), plant mid-April to early May.

Tuber set (the initiation of new potatoes) occurs when soil temperatures are below 68°F. Per Cornell, once soil temperatures exceed 80°F, tuber set stops and plants may abort developing tubers. This is why potatoes grown into midsummer heat in zones 7—8 often have reduced yields — the tuber-setting period is cut short.

For zone 7a, an early spring planting (mid-April) produces the longest possible tuber-setting window before summer heat. A fall potato crop (plant mid-July for harvest before first frost) is also possible.

Seed potatoes and chitting

Certified seed potatoes: Always plant from certified disease-free seed potatoes, not from grocery store potatoes. Per Cornell Cooperative Extension, grocery store potatoes may carry late blight, scab, or virus diseases, and many are treated to prevent sprouting. Certified seed potatoes from a reputable source are the most important disease prevention step.

Chitting (pre-sprouting): Per Penn State Extension, placing seed potatoes in a bright, cool location (50—60°F) for 2—4 weeks before planting allows sprouts to develop before planting. Short, stubby sprouts 1/2—1 inch long are ideal; long, spindly sprouts are the result of chitting in low light. Chitting advances maturity by 1—2 weeks.

Cutting seed pieces: Per Cornell, cut large seed potatoes into pieces with 2—3 eyes each, at least 1.5—2 ounces per piece. Allow cut surfaces to suberize (callus) for 2—3 days at room temperature before planting to reduce rotting. Per NC State Extension, apply sulfur dust to cut surfaces to further reduce disease risk if late-season rots are common in your area.

Small seed potatoes under 2 ounces can be planted whole.

Planting depth and spacing

Per Cornell Cooperative Extension, plant seed pieces 3—4 inches deep, 12 inches apart in rows 30—36 inches apart. Per Penn State Extension, spacing of 12 inches within the row is the standard for most varieties; closer spacing (9—10 inches) produces smaller tubers in larger numbers, useful for \"new potato\" crops; wider spacing (15 inches) produces fewer but larger tubers.

Hilling: the critical management practice

Hilling — mounding soil around potato plants as they grow — serves two functions: it creates more growing volume for tuber development (tubers only form above the seed piece, in the hilled soil), and it prevents greening of tubers exposed to light. Per Cornell Cooperative Extension, tubers exposed to sunlight turn green and produce solanine, which is toxic.

Per Cornell, begin hilling when plants are 6—8 inches tall, drawing soil up around the stem to leave only the top 3—4 inches of plant exposed. Repeat every 2 weeks until plants begin to flower or the hilled mounds are 8—10 inches tall. Per Penn State Extension, heavy mulch (straw, shredded leaves) can substitute for soil hilling, particularly in hot climates where soil over-compaction and heat buildup are concerns.

Watering

Per Cornell Cooperative Extension, potatoes need 1—2 inches of water per week during active growth. Per Penn State Extension, consistent moisture is especially critical from tuber set through tuber sizing (approximately 6—10 weeks after planting). Drought stress during this period causes hollow heart (internal cavities in tubers) and growth cracking.

Reduce irrigation significantly 2 weeks before harvest to allow skin to set and reduce rot risk. Soaker hose irrigation at the base of plants is preferred; overhead irrigation wets foliage and promotes late blight.

Late blight management

Late blight (Phytophthora infestans) can destroy a potato planting in 7—10 days under cool, wet conditions. Per Cornell Cooperative Extension, \"late blight can be devastating in a cool, wet summer.\" Symptoms: dark brown to black water-soaked lesions on leaves, white sporulation on leaf undersides in wet conditions, rapid collapse of entire plant canopy.

Per Penn State Extension, management practices:

• Plant certified disease-free seed potatoes
• Choose varieties with disease tolerance ('Kennebec', 'Elba', 'Defender')
• Avoid overhead irrigation; use drip or soaker hose
• Rotate potatoes away from tomatoes, peppers, and eggplant (same solanine family diseases)
• In high-pressure years, apply copper-based fungicide (Bordeaux mixture or copper hydroxide) preventively every 7—10 days beginning at first emergence

Once late blight appears, infected foliage should be removed and disposed of (not composted). Per UC IPM, destroy potato vines with a hard frost or physical removal at least 2 weeks before harvest to prevent blight spores from migrating to tubers.

Common scab (Streptomyces scabies)

Common scab is a bacterial disease that produces rough, corky lesions on tuber surfaces. Per Cornell, scab is most severe in alkaline soils (pH above 7.0) and dry conditions during tuber set. Per NC State Extension, maintain soil pH between 5.0—5.2 in fields with scab history; at pH 5.2 or below, scab incidence drops significantly. Most other vegetables prefer pH 6.0—6.8, so scab management creates a soil pH conflict — potato-specific beds or raised beds with lower pH are the practical solution for repeat scab problems.

Harvesting

Per Cornell Cooperative Extension, new potatoes can be harvested 2—3 weeks after flowering begins. Full-size storage potatoes are ready when foliage yellows and dies back completely.

Cure storage potatoes (for long-term storage) at 50—60°F with high humidity (85—95%) for 10—14 days after harvest per Penn State Extension. Curing heals minor skin wounds and develops thicker skin. After curing, store at 40—50°F with high humidity in darkness; light triggers greening. Per Cornell, properly stored potatoes keep 3—6 months.

Pests and diseases

Colorado potato beetle (Leptinotarsa decemlineata): Per Cornell, the most damaging insect pest of potatoes in the Northeast. Both adults and larvae defoliate plants. Per NC State Extension, hand-pick adults and egg masses; apply Monterey BT for larval control. floating row cover can exclude adults early in the season.

Wireworms: Soil-dwelling larvae that tunnel into tubers. Per Penn State Extension, most common in soil recently converted from lawn or sod. Avoid planting potatoes in recently tilled sod areas.

Aphids: Per Cornell, potato aphids transmit several viruses. Safer insecticidal soap manages populations without harming beneficial insects.

Common problems

Recommended gear: Best Soaker Hose for Vegetable Gardens (2026) — our buyer's guide covering picks for every budget, ranked by Extension publication consensus and personal use.

Frequently asked

What is the difference between new potatoes and storage potatoes?

New potatoes are harvested young, 2—3 weeks after flowering, per Cornell. They have thin skin that rubs off and a waxy, moist texture suited for boiling and salads. They do not store well. Storage (mature) potatoes are harvested after the foliage has died back completely; their skin has set and thickened. After proper curing (10—14 days at 50—60°F, high humidity), storage potatoes keep 3—6 months.

Why do I need to hill potatoes?

Per Cornell Cooperative Extension, potato tubers develop only above the seed piece, in the soil surrounding the stem. Hilling creates more soil volume in which tubers can form and prevents light exposure that causes greening and solanine formation. Per Penn State Extension, unhilled potato plants typically produce significantly fewer and smaller tubers than hilled plants.

Do potatoes and tomatoes share diseases?

Yes. Both are in the Solanaceae family and share several serious pathogens, including late blight (Phytophthora infestans), early blight (Alternaria solani), and Fusarium wilt. Per Cornell, rotate potatoes away from tomatoes, peppers, and eggplant for at least 3 years. In a small garden where rotation space is limited, raised beds with fresh growing media can reduce but not eliminate soilborne disease pressure.

How do I prevent green potatoes?

Greening is caused by chlorophyll production in response to light exposure. Per Penn State Extension, prevent greening by hilling soil over tubers throughout the growing season, using heavy mulch (straw, shredded leaves), and harvesting before light exposure occurs. Green potatoes contain solanine and should not be eaten — the compound is toxic and is not destroyed by cooking.