Seed Potatoes Explained: What They Are & Why They Matter

Seed potatoes are disease-free tubers specifically grown and certified for planting, not actual seeds. Unlike grocery store potatoes treated with sprout inhibitors, certified seed potatoes ensure healthy crops, prevent disease transmission, and maintain varietal purity for optimal harvests.

Many gardeners mistakenly believe they can plant regular potatoes from the grocery store. This common error leads to disappointing harvests, diseased plants, and potential soil contamination. Understanding the critical differences between seed potatoes and table potatoes is essential for successful cultivation.

What Exactly Are Seed Potatoes?

Despite the name, seed potatoes aren't seeds at all—they're whole or cut tubers specifically grown for replanting. These potatoes undergo rigorous certification processes to ensure they're free from viruses, bacteria, and fungi that commonly affect commercial potato crops.

The term "seed" refers to their purpose rather than their biological classification. When you purchase certified seed potatoes, you're investing in disease management and varietal integrity that grocery store potatoes simply cannot provide.

Why Grocery Store Potatoes Fail as Planting Material

Supermarket potatoes face three critical problems when used for planting:

Characteristic	Seed Potatoes	Grocery Store Potatoes
Disease Status	Certified disease-free	Often carry viruses (PVY, PLRV)
Sprouting Ability	Naturally sprout-ready	Treated with sprout inhibitors
Varietal Purity	True to type	May produce unexpected varieties
Legal Status	Approved for planting	Often treated with prohibited chemicals

The Certification Process Timeline

Certified seed potatoes undergo a multi-year production cycle that ensures quality:

1. Year 1: Breeder selects parent stock in controlled greenhouse conditions
2. Year 2: First field generation grown under strict isolation protocols
3. Year 3: Second field generation with mandatory disease testing
4. Year 4: Commercial seed production with regular field inspections
5. Harvest: Each tuber individually inspected before certification

This rigorous process, documented by the USDA Agricultural Marketing Service, explains why certified seed potatoes cost more but deliver significantly better results.

When Non-Certified Potatoes Might Work (With Caveats)

While certified seed potatoes are always recommended, some gardeners achieve limited success with grocery potatoes under specific conditions:

• Short-term experiments: For educational purposes with no expectation of harvest
• Isolated containers: When grown in sterile potting mix with no soil contact
• Non-commercial use: Small-scale personal gardening with disease monitoring

However, agricultural extension services like University of Minnesota Extension strongly advise against this practice due to the high risk of introducing potato viruses into your garden ecosystem.

Selecting Quality Seed Potatoes: A Practical Guide

Follow these evidence-based selection criteria for optimal results:

Visual Inspection Checklist

• Firm texture with no soft spots or wrinkles
• Smooth skin without cuts, bruises, or discoloration
• Multiple healthy "eyes" (growth points)
• No signs of sprouting (except for pre-chitted varieties)
• Official certification tag visible

Proper Storage Before Planting

Store seed potatoes at 45-50°F (7-10°C) with 90% humidity for 2-4 weeks before planting. This "chitting" process encourages strong sprout development. Avoid refrigeration, which damages potato physiology.

Avoiding Common Seed Potato Mistakes

Even experienced gardeners make these critical errors:

• Planting too early: Soil temperature should be at least 45°F (7°C) at planting depth
• Improper cutting: Cut pieces must have 1-2 eyes and 1.5-2 oz weight minimum
• Skipping curing: Allow cut surfaces to callus for 24-48 hours before planting
• Overcrowding: Maintain 12-15 inch spacing between plants for proper development

Maximizing Your Potato Harvest

For best results, plant seed potatoes in well-drained, loose soil with pH 5.0-6.5. Hill soil around emerging plants when they reach 6-8 inches tall to protect developing tubers from sunlight (which causes greening). Water consistently but avoid saturation, providing 1-2 inches per week.

Remember that different varieties have specific growing requirements—early varieties mature in 70-90 days while late varieties take 120-140 days. Consult your seed potato supplier's recommendations for your specific variety.

Can I use organic potatoes from the store as seed potatoes?

Organic potatoes still carry disease risks and may have been treated with natural sprout inhibitors. Certified seed potatoes undergo specific disease testing that grocery store potatoes don't receive, making them the only reliable choice for planting.

How much do seed potatoes cost compared to regular potatoes?

Seed potatoes typically cost 2-4 times more than table potatoes. This reflects the certification process, disease testing, and specialized handling required to produce planting-quality tubers. The higher initial cost prevents crop failure and potential soil contamination.

Do I need to cut seed potatoes before planting?

Small seed potatoes (1-2 inches) can be planted whole. Larger ones should be cut into pieces with 1-2 eyes each, weighing at least 1.5 ounces. Allow cut surfaces to dry for 24-48 hours before planting to prevent rotting.

How long do seed potatoes remain viable before planting?

Properly stored seed potatoes maintain viability for 2-4 months. Store at 45-50°F with high humidity. Warmer temperatures encourage premature sprouting while colder temperatures damage tuber physiology.