When to Plant Potatoes: The Best Dates for Zones 4-9 (Spring & Fall)

One of the most common questions I get at The Planting Key is simply: “When is the exact right day to plant my potatoes?”

It sounds like a simple question, but if you ask three different gardeners, you might get three different answers. That’s because the “right time” isn’t a calendar date—it’s a balance between soil temperature and frost risk.

If you plant too early in cold, wet soil, your seed potatoes will rot before they sprout. If you plant too late, especially in warmer climates, the summer heat will stop the tubers from growing just as they are getting started.

This guide cuts through the confusion. I’ve analyzed data from top university extension programs—from Cornell to Texas A&M—to create a planting calendar that balances these risks for USDA Zones 4 through 9.

The Best Time to Plant Potatoes by Zone

The best time to plant potatoes depends entirely on your climate’s core challenge: avoiding seed rot from cold soil, or avoiding tuber failure from intense heat. This is why the planting rule changes depending on your region.

• For most gardeners in temperate or cold climates (Zones 4-7), the rule is to plant in early spring, 2 to 4 weeks before your last expected frost date. This guideline is confirmed by experts at universities like Cornell and the University of California. The key is waiting until the soil is “workable” and has warmed above the absolute minimum of 40°F (4°C), as planting in colder, wet soil is the biggest risk for seed rot.
• For gardeners in hot climates (Zones 8-9), the strategy is different. The enemy is summer heat, so planting must happen earlier, at 4 to 6 weeks before the last frost date, following guidance from hot-climate experts like the Texas A&M AgriLife Extension. A second planting window also opens in late summer for a fall crop, which, for most hot climates, is planted 14 to 16 weeks before your average first fall frost date.

Potato Planting Calendar (USDA Zones 4-9)

How to Read This Calendar

The calendar below provides key planting dates based on two strategies: Safe and Aggressive.

For Spring Planting:

• Aggressive: This is the earliest possible planting date, designed to maximize your growing season. It carries a risk of a late frost, and you must be prepared to protect your plants.
• Safe: This is the most reliable planting date. It minimizes frost risk by waiting until the weather has settled.

For Fall Planting (Zones 8-9):

• Aggressive: This is the latest possible planting date. This strategy allows you to plant after the summer heat has passed, but it carries a risk of an early frost damaging your crop before it’s fully mature.
• Safe: This is the earliest fall planting date. It provides a safe window from frost.

Potato-Specific Timing Rules

The key planting dates in this calendar are calculated based on the following authoritative growing rules:

Spring Planting: (Primary Method for most zones)

These dates are for planting seed potatoes. My calendar uses a two-part climate-specific rule to provide the most accurate advice for your location, as the strategy for cold climates is the opposite of the strategy for hot climates.

• For Zones 4-7 (Temperate/Cold Climates): The planting window is set at 2 to 4 weeks before your average last spring frost date, following guidance from institutions like Cornell University. In these regions, the goal is to wait until the soil is “workable” and has warmed above the absolute minimum (40°F/4°C) to avoid seed rot, as planting too early in cold, wet soil is the biggest risk.
• For Zones 8-9 (Hot Climates): The planting window is set earlier, at 4 to 6 weeks before your average last spring frost date, following guidance from hot-climate experts like the Texas A&M AgriLife Extension. In these regions, the biggest enemy is summer heat. The goal is to plant as early as possible (risking frost) to ensure the potatoes can fully mature before the intense heat of early summer arrives and stops tuber production.

Fall Planting: (For Warmer Zones 8+)

These dates are for planting seed potatoes. The planting window must be calculated by counting backward from your average first fall frost date. My calendar uses the authoritative rule recommended by top university extension programs, such as the Texas A&M AgriLife Extension, which sets the planting window at 14 to 16 weeks before your average first fall frost date.

This timing is critical and presents a significant challenge: you will be planting in the hottest part of the year (late July to August). The goal during this period is not for the plant to thrive or form tubers, but simply to survive the heat. To have any chance of success, you must apply a thick layer of organic mulch (like straw or shredded leaves) immediately after planting to keep the soil as cool and moist as possible, and you must water consistently.

Once the intense heat finally breaks in early fall, the established plants will then have just enough time to produce a full harvest in the cool, mild weather before the first hard frost kills the plant. For this crop, I always recommend choosing an early- or mid-maturing variety.

A Critical Note for Warm-Climate Gardeners (Zones 8 & 9)

My timing rules for fall are based on a simple, scientific goal: harvesting before your first fall frost kills the plant. This often means planting in the heat of late summer (August) to allow enough time for maturation.

You may see conflicting advice online suggesting planting in October. That advice is only intended for truly frost-free, subtropical regions (like Florida or coastal California) where potatoes can safely grow all winter. For any gardener in a region that does get a frost, you must use this frost-date-based calendar—supported by university research—to avoid a failed crop.

✔ Accuracy is my priority. The key planting dates in this calendar are calculated based on representative Aggressive and Safe frost date baselines established for each zone. Because your garden’s microclimate may vary, I strongly recommend that you verify your local frost dates for the most accurate timing. Learn My Methodology & Find a Frost Date Tool Here.

Understanding the Planting Windows

Spring Planting: A Tale of Two Strategies

Spring planting is the standard method, but the “when” depends entirely on your climate’s biggest enemy.

In Hot Climates (Zones 8-9): The main enemy is summer heat. You must plant earlier, at 4 to 6 weeks before the last frost. This is a race against the clock. The goal is to get the plants in the ground (risking frost) to ensure they can mature before the intense heat (above 85°F) arrives and stops tuber production.

In Cold Climates (Zones 4-7): The main enemy is cold, wet soil. As my calendar shows, you should plant 2 to 4 weeks before the last frost. This is a balancing act—waiting for the soil to warm just above 40°F (4°C) to prevent rot, while still planting early enough for the long growing season.

Fall Planting: The High-Risk, High-Reward Window

In warmer climates (Zones 8-9), you can get a second harvest, but this is an advanced technique. As my Timing Rules section explains, the 14-16 week rule means you must plant in the peak of late summer heat (often August).

This is a high-risk strategy. The goal is simply to keep the seed pieces alive (using heavy mulch and water to cool the soil) until the weather breaks. The plants will then mature in the cooler, gentler weather of autumn.

The Danger Zone: Why Summer Heat is the Enemy

Potatoes are a cool-season crop that perform best in cool summers. The timing of your harvest is a race against a non-negotiable deadline: as Utah State University warns, high soil temperatures—specifically above 90°F (32°C)—can stop the plant from forming tubers altogether. This “heat deadline” is the single most important factor in my spring planting strategy and the reason why gardeners in hot climates (Zones 8-9) must plant so much earlier than gardeners in the north.

Key Temperatures for Success

While the calendar provides a general timeline, the soil itself gives the most accurate signal. Here are the key temperature benchmarks to follow:

• Minimum Soil Temperature: 40°F (4°C) This is the absolute minimum temperature for planting. However, planting in soil this cold, especially if it’s wet, carries a higher risk of seed rot.
• Optimal Air Temperature for Growth: 65°F to 70°F (18°C to 21°C) Potatoes perform best when summers are cool, specifically in the 65-70°F range. The plant can tolerate slightly warmer or cooler temperatures, but this is the sweet spot for vigorous foliage and tuber formation.

Advanced Strategies for Timing Your Harvest

Pro Technique: Succession Planting

Succession planting with potatoes isn’t about planting new crops every few weeks. Instead, it involves planting different varieties with different maturity dates at the same time.

By planting a mix of early-season (65-75 days), mid-season (80-90 days), and late-season (90+ days) varieties, you can enjoy a staggered harvest that lasts for months.

Tips for an Earlier Start

If you’re eager to get a head start in the spring, especially in cooler zones, these techniques are very effective:

• Choose a Cold-Tolerant Variety: Some potato varieties are inherently better at handling cooler soil temperatures.
• Use Plastic Mulch: Laying black or clear plastic mulch over your planting bed for a week or two before planting is an excellent way to warm the soil.
• Pre-Sprouting (Chitting): You can get a jump on the season by letting the seed potatoes sprout indoors in a bright, cool spot for a few weeks before planting. This can speed up your harvest by a week or two.

What Comes Next?

Now that you have marked your ideal planting window on the calendar, the next step is execution. Getting the timing right prevents rot and heat stress, but the size of your harvest depends on what you do after the seed hits the soil—from proper cutting and curing to the critical “hilling” process.

I have documented every step of the process in my complete guide: How to Grow Potatoes