When to Dig Up Potato Plants: Harvest Timing Guide

Dig up early potatoes approximately 7-10 weeks after planting when flowers appear, and harvest maincrop potatoes 2-3 weeks after the foliage naturally dies back for optimal flavor and storage potential. The ideal soil temperature for harvesting is between 50-65°F (10-18°C).

Knowing exactly when to dig up potato plants makes the difference between harvesting perfect, flavorful tubers and ending up with damaged or underdeveloped potatoes. Whether you're growing early varieties for summer salads or maincrop potatoes for winter storage, timing your harvest correctly ensures maximum yield and quality from your garden efforts.

Understanding Potato Growth Stages and Harvest Timing

Potatoes progress through distinct growth phases that determine their readiness for harvest. Unlike many vegetables with fixed harvest dates, potato readiness depends on visual cues from the plants themselves. Understanding these growth stages helps you determine the best time to harvest potatoes for your specific needs.

Growth Stage	Time After Planting	Visual Indicators	Harvest Purpose
Vegetative Growth	0-6 weeks	Green stems and leaves emerging	Not ready for harvest
Tuber Initiation	4-8 weeks	Flowers beginning to form	Early potatoes ready
Tuber Bulking	8-14 weeks	Full flowering, vigorous growth	Maincrop development
Maturity	12-20 weeks	Foliage yellowing and dying back	Maincrop harvest

Key Signs Your Potatoes Are Ready to Harvest

Don't rely solely on calendar dates when determining when to dig up potatoes—your plants provide clear visual signals. These indicators vary depending on whether you're harvesting early potatoes or maincrop varieties.

For Early Potatoes (New Potatoes)

Early varieties like 'Yukon Gold' or 'Red Norland' can be harvested when the plants begin flowering, typically 7-10 weeks after planting. At this stage:

• Flowers appear on the plant
• Foliage remains mostly green and healthy
• Tubers are small (1-2 inches in diameter)
• Skins rub off easily when touched

These 'new potatoes' have thin skins and a delicate flavor perfect for immediate consumption but won't store well.

For Maincrop Potatoes

Maincrop varieties like 'Russet Burbank' or 'Kennebec' require more patience. Harvest these when:

• Foliage turns yellow and begins to die back naturally
• Stems become dry and brittle
• Soil around plants appears slightly mounded from tuber growth
• At least 2-3 weeks have passed since foliage died completely

This waiting period after foliage dies allows the skins to thicken, which is crucial for proper storage. According to the University of Minnesota Extension, this curing process in the ground significantly improves storage life.

Proper Technique for Digging Up Potatoes

Even with perfect timing, improper harvesting can damage your crop. Follow these steps for how to harvest potatoes without damaging them:

1. Choose the right day: Harvest when soil is dry but not baked hard. Avoid harvesting immediately after heavy rain when soil is soggy.
2. Cut back foliage: For maincrop potatoes, cut stems to 4-6 inches above soil 2-3 weeks before harvesting to help skins set.
3. Start from the perimeter: Use a garden fork rather than a shovel, inserting it 8-10 inches from the plant stem to avoid piercing tubers.
4. Lift gently: Push the handle down to lift soil and potatoes upward, working your way toward the center of the plant.
5. Hand harvest near the stem: Carefully remove soil by hand within 4 inches of the stem where potatoes cluster.
6. Avoid sun exposure: Don't leave harvested potatoes in direct sunlight for more than 20-30 minutes to prevent greening.

Post-Harvest Handling for Maximum Storage Life

What you do after digging up potatoes affects their longevity. Proper post-harvest handling ensures your potato harvesting efforts pay off throughout the winter months.

Curing Process

Maincrop potatoes need curing before long-term storage:

• Keep in a single layer in a dark, humid (85-95% humidity), well-ventilated area
• Maintain temperature between 50-60°F (10-15°C) for 10-14 days
• This allows skins to fully harden and minor wounds to heal

Storage Conditions

After curing, store potatoes in a cool, dark place:

• Ideal temperature: 38-40°F (3-4°C)
• High humidity (90-95%)
• Good ventilation to prevent moisture buildup
• Check monthly for rot and remove affected tubers immediately

According to research from the Rutgers New Jersey Agricultural Experiment Station, properly stored maincrop potatoes can last 5-8 months under optimal conditions.

Climate Considerations for Harvest Timing

Your local climate significantly affects when to dig up potatoes in different climates. Gardeners in various regions need to adjust their harvest timing based on these factors:

• Cooler northern climates: Maincrop potatoes may need the full 18-20 weeks to mature. Harvest before first hard frost.
• Warmer southern climates: Potatoes mature faster but may need harvesting earlier to avoid heat damage. Consider planting in fall for winter harvest.
• Short-season areas: Focus on early varieties that mature in 70-90 days rather than maincrop types.
• Wet climates: Harvest immediately after foliage dies to prevent tuber rot in moist soil.

Common Potato Harvesting Mistakes to Avoid

Even experienced gardeners sometimes make these errors when determining when is the right time to dig potatoes:

• Harvesting too early: Results in small yields and thin-skinned potatoes that don't store well
• Waiting too long: Increases risk of rot, pest damage, and exposure to frost
• Using improper tools: Shovels often pierce tubers; garden forks are safer
• Leaving potatoes in sun: Causes greening and production of toxic solanine
• Washing before storage: Moisture promotes rot; only brush off excess soil

Remember that different potato varieties have different maturity dates. Always check the specific days to maturity for your variety, but prioritize the visual cues from your plants over calendar dates for the best time to harvest potatoes.

Frequently Asked Questions

How can I tell if my potatoes are ready to harvest without digging them up?

Check for natural yellowing and dying back of the foliage, which typically occurs 2-3 weeks before potatoes are ready for harvest. For early potatoes, look for flowering plants. You can gently feel around the base of the plant to check for tuber size without fully digging up the plant.

What happens if I harvest potatoes too early?

Harvesting potatoes too early results in smaller yields with thin skins that don't store well. Early-harvested potatoes have higher moisture content and are best used immediately rather than stored. They'll have a more delicate flavor but won't last beyond a week or two.

Can I leave potatoes in the ground over winter?

Generally no, as most potato varieties will rot in cold, wet winter soil. In mild climates with well-drained soil and no frost, some gardeners have success leaving potatoes in the ground, but this risks disease buildup and pest damage. It's safer to harvest and store properly.

Why are my harvested potatoes green in spots?

Green spots develop when potatoes are exposed to sunlight after harvest, producing solanine - a toxic compound. Cut away all green areas before cooking, as they can cause stomach upset. To prevent this, keep harvested potatoes out of direct sunlight and cover them with a cloth or paper while working.

How long after the plants die should I wait to harvest potatoes?

Wait 2-3 weeks after the foliage has completely died back before harvesting maincrop potatoes. This allows the skins to thicken and mature, which significantly improves storage life. During this waiting period, the potato skins harden and minor wounds heal, reducing susceptibility to rot during storage.