When To Plant Potatoes In Iowa

If you’re planning your garden in the Hawkeye State, knowing when to plant potatoes in Iowa is the first step to a great harvest. Getting the timing right makes all the difference between a bumper crop and disappointing yield.

This guide will walk you through the optimal planting windows, soil prep, and simple steps for success. Let’s get your spuds in the ground at the perfect time.

The classic rule for planting potatoes is to get them in the ground around the time of the last spring frost. In Iowa, this timing varies significantly from north to south due to our state’s climate range.

Here’s a general breakdown by region:

Southern Iowa (USDA Zone 5): Optimal planting time is early to mid-April.
Central Iowa (USDA Zone 5): Aim for mid to late April.
Northern Iowa (USDA Zone 4): Best to wait until late April or early May.

A perfect soil cue is temperature. Use a soil thermometer and plant when the soil at a 4-inch depth consistently reaches 45°F. Planting in cold, wet soil can cause seed pieces to rot instead of sprout.

Understanding Your Iowa Frost Dates

Your local average last frost date is the best calendar guide. You can plant potatoes 2-4 weeks before this date. The soil is often workable by then, even if a light late frost still occurs.

Potato foliage can handle a light frost, but a hard freeze (below 28°F) will damage it. Having some row cover or old blankets on hand for cold nights is a smart precaution. If foliage gets nipped, plants will often send up new growth.

Can You Plant Potatoes in Fall in Iowa?

Fall planting is generally not recommended for Iowa. Our winters are too cold, and the ground freezes deeply, which would kill the tubers. For a continuous harvest, focus on succession planting in spring or choose varieties with different maturity dates.

Choosing the Right Potato Varieties for Iowa

Selecting varieties suited to our climate improves your success. Consider these types:

Early Season (70-90 days): ‘Yukon Gold’, ‘Red Norland’, ‘Irish Cobbler’. Great for an early summer harvest and avoiding some pest pressure.
Mid-Season (90-110 days): ‘Kennebec’, ‘Viking Purple’, ‘Gold Rush’. These are reliable workhorses for storage.
Late Season (110-135 days): ‘Russet Burbank’, ‘German Butterball’. Need a longer growing season; best for central and southern Iowa.

How to Prepare for Planting Potatoes

Good preparation sets the stage. A week or two before your planned planting date, get your seed and site ready.

1. Sourcing and Preparing Seed Potatoes

Always use certified disease-free seed potatoes from a garden center or reputable catalog. Do not use potatoes from the grocery store, as they may carry disease or be treated to prevent sprouting.

Chitting (Pre-sprouting): Place seed potatoes in a bright, cool (50-60°F) spot for 1-2 weeks before planting. This encourages strong, stubby sprouts.
Cutting: A day before planting, cut larger seed potatoes into pieces. Each piece should be about the size of a golf ball and have at least 1-2 “eyes” (sprout buds).
Curing: Let the cut pieces sit out so the cut surfaces dry and form a callus. This helps prevent rot in the ground.

2. Selecting and Preparing the Garden Site

Potatoes need full sun (at least 6 hours daily) and loose, well-drained soil. Heavy, clay-rich Iowa soil needs amending.

Soil pH: Aim for slightly acidic soil, between 5.0 and 6.0. This helps prevent scab disease.
Amend Soil: Work in several inches of compost or well-rotted manure the fall before or early spring. This improves drainage and fertility.
Avoid Fresh Manure: It can promote scab and may be to strong, leading to poor tuber development.

Step-by-Step Planting Guide

Follow these steps on your chosen planting day.

Dig Trenches or Holes: Dig trenches about 6-8 inches deep. Space trenches 2.5 to 3 feet apart. You can also use individual holes for a small planting.
Add Light Fertilizer: Sprinkle a balanced, low-nitrogen organic fertilizer or potato-specific fertilizer in the bottom of the trench. Mix it lightly with the soil.
Place Seed Pieces: Place seed pieces cut-side down, with the eyes facing upward. Space them 10-12 inches apart in the trench.
Cover Gently: Cover the seed pieces with 4 inches of soil. Do not pack it down tightly. Leave the remaining soil beside the trench for later hilling.
Water Lightly: Give the planted area a gentle watering to settle the soil, but don’t soak it.

The Importance of Hilling Potatoes

Hilling is the practice of mounding soil around the growing stems. This is crucial because it protects developing tubers from sunlight (which turns them green and toxic) and encourages more potatoes to form along the buried stem.

First Hill: When plants are 6-8 inches tall, use a hoe to pull soil from between the rows up around the base of the plants, leaving just the top few leaves exposed.
Second Hill: Repeat the process 2-3 weeks later. Continue until the hills are about 12-15 inches tall. You can also use straw or shredded leaves for hilling.

Caring for Your Potato Crop

Consistent care through the season leads to healthy plants.

Watering and Feeding

Potatoes need about 1-2 inches of water per week, especially once tubers start forming (when plants flower). Water deeply and consistently. Erratic watering can cause knobby or hollow tubers.

Side-dress with a low-nitrogen fertilizer when you start hilling. To much nitrogen leads to huge plants but small potatoes.

Managing Pests and Problems

Common Iowa potato issues include:

Colorado Potato Beetle: Hand-pick orange egg clusters, larvae, and adults. Use row covers early in the season.
Early/Late Blight: Promote air flow by proper spacing and hilling. Remove and destroy affected plants. Choose resistant varieties.
Flea Beetles: They create small shot holes in leaves. Row covers are effective protection.

Rotate your potato patch to a different area of the garden each year to reduce disease carryover in the soil.

Harvesting and Storing Your Iowa Potatoes

When to Harvest

New Potatoes: You can gently dig for tender “new” potatoes about 2-3 weeks after plants finish flowering.
Storage Potatoes: For main harvest, wait until the plant vines have completely died back. This allows skins to toughen up for storage.

How to Harvest and Cure

Use a digging fork on a dry day, starting well away from the plant to avoid spearing tubers.
Let potatoes sit on the soil surface for 1-2 hours to dry.
Move them to a dark, well-ventilated, humid place (like a garage) for 10-14 days to cure. This heals minor cuts and thickens the skin.
After curing, brush off dry soil and store in a cool (38-45°F), dark, humid place. Do not wash them until ready to use.

Frequently Asked Questions (FAQ)

What is the latest you can plant potatoes in Iowa?

For a fall harvest, you can plant early-season varieties as late as mid-June in central Iowa. Later plantings may produce smaller tubers but can be worthwhile for a fresh fall crop.

Can I plant store-bought potatoes that have sprouted?

It’s not recommended. Store-bought potatoes are often treated with sprout inhibitors and are more suseptible to soil-borne diseases that can ruin your garden bed.

How deep should I plant potato pieces?

Plant them about 4 inches deep initially. The final depth after all hilling will be much deeper, which is what creates the ideal environment for tuber formation.

Do potatoes need a lot of fertilizer?

They need moderate feeding. To much nitrogen gives you leaves, not potatoes. A balanced fertilizer or one higher in phosphorus and potassium is best for tuber development.

Why are my potato leaves turning yellow?

Yellowing leaves late in the season is normal as plants mature. Yellowing early can signal overwatering, a nutrient deficiency, or the onset of disease like early blight. Check your watering habits and look for other symptoms.

By following this guide and paying attention to soil temperature and local conditions, you’ll master the art of timing your potato planting in Iowa. With a little preparation and consistent care, you’ll be rewarded with a plentiful harvest of homegrown potatoes to enjoy for months to come.