For many gardeners, potatoes are a spring-planted staple. But did you know you can enjoy a second, fresh harvest from your own backyard later in the year? Knowing exactly when to plant potatoes for fall harvest is the key to success. This guide will walk you through the timing, varieties, and techniques you need for a bountiful autumn yield.
Getting the timing right is the most critical step. Plant too early, and your seed potatoes may rot in the summer heat. Plant too late, and they won’t have enough time to mature before the first hard freeze.
When to Plant Potatoes for Fall Harvest
This isn’t a single date on the calendar. Your planting time depends entirely on your local climate and the first expected frost in your area.
The Golden Rule: Count backwards from your first average fall frost date. Most potato varieties need 90 to 120 days to reach full maturity. For a fall harvest, you’ll aim to plant so the potatoes mature around or just after that first frost.
Here’s a simple formula:
1. Find your area’s average first fall frost date. (Check with your local extension office or a reliable gardening almanac).
2. Look at the “days to maturity” for your chosen potato variety (e.g., 100 days).
3. Add 14 days to that number for the “fall factor.” Cooler fall days and shorter sunlight hours slow growth a bit.
4. Count that total number of days backwards from your frost date. That’s your target planting window.
Example: Frost date is October 20. Variety needs 90 days. 90 + 14 = 104 days. Count back 104 days from October 20 = plant around July 8.
Choosing the Right Potatoes for Autumn
Not all potatoes are created equal for fall planting. You need varieties with a shorter growing season.
Best Potato Types for Fall:
* Early Season (75-90 days): These are your best bet. They mature quickly.
* ‘Yukon Gold’: A versatile, all-purpose favorite.
* ‘Red Norland’: Smooth, red skin, excellent for boiling.
* ‘Irish Cobbler’: An early, flavorful heirloom.
* Mid-Season (90-110 days): Can work if you have a long, mild fall.
* ‘Kennebec’: A reliable, high-yielding all-purpose potato.
* ‘Viking’: Known for it’s beautiful red skin.
Avoid late-season varieties (120+ days), as they likely won’t have enough time to develop.
Preparing Your Seed Potatoes
You’ll be using “seed potatoes”—certified disease-free tubers from a garden center, not grocery store spuds. Here’s how to get them ready for a summer planting.
1. Source and Store: Buy your seed potatoes in late spring. Store them in a cool, dark, well-ventilated place until planting time. This keeps them from sprouting to early.
2. “Green-Sprouting” (Chitting): About 4-6 weeks before your planting date, bring the seed potatoes into indirect light. This encourages short, sturdy green sprouts. For fall planting, this step is very helpful to give them a head start.
3. Cutting and Curing: A day or two before planting, cut larger seed potatoes into pieces. Each piece should be about the size of a golf ball and have at least 2-3 “eyes” (sprouts). Let the cut pieces air-dry to form a protective callus over the cuts. This prevents rot in the warm summer soil.
Site and Soil Preparation
Potatoes need loose, well-draining soil and full sun (at least 6-8 hours).
* Location: Choose a spot that didn’t grow potatoes, tomatoes, or peppers the previous year to prevent disease buildup.
* Soil Amendment: Work in several inches of compost or well-rotted manure. Potatoes are heavy feeders, but avoid fresh manure or excessive nitrogen, which leads to leafy tops and tiny tubers.
* pH Level: Aim for slightly acidic soil, between 5.0 and 6.0. You can test your soil and amend if needed.
Step-by-Step Planting Guide
Follow these steps for planting your summer-sown potatoes.
1. Time it Right: Plant on your calculated date, preferably on a cloudy day or in the evening to reduce stress.
2. Water the Soil: Moisten the planting area thoroughly a day before if the soil is dry.
3. Dig Trenches or Holes: Dig trenches about 6 inches deep and 3 feet apart.
4. Place Seed Pieces: Set the seed pieces cut-side down, eyes facing up, 10-12 inches apart in the trench.
5. Cover Gently: Cover with 4 inches of soil. Do not pack it down tightly.
6. Water Well: Give them a good initial watering to settle the soil.
Caring for Your Fall Potato Crop
Summer-planted potatoes need attentive care to thrive in the warmer initial conditions.
* Watering: Consistent moisture is crucial, especially during summer’s heat and during tuber formation. Water deeply 1-2 times per week, aiming for about 1-2 inches of water. Avoid letting the soil dry out completely, but also ensure it’s not soggy.
* Hilling: When plants are about 6-8 inches tall, mound soil around the stems, leaving just the top few leaves exposed. Repeat this process every few weeks. Hilling protects developing tubers from sunlight (which turns them green and toxic) and cools the roots.
Mulching: Apply a thick layer of straw or shredded leaves after hilling. This is vital for fall potatoes. Mulch conserves moisture, suppresses weeds, and most importantly, keeps the soil temperature cooler during hot summer weeks.
* Pest & Disease Watch: Keep an eye out for Colorado potato beetles and signs of blight. Remove pests by hand and use row covers if needed. Good air circulation helps prevent fungal diseases.
Harvesting Your Autumn Bounty
Your harvest time depends on what type of potato you want.
* For “New” Potatoes: You can carefully dig around plants for tender, small potatoes about 2-3 weeks after the plants finish flowering.
* For Mature, Storage Potatoes: Wait until the tops of the plants (vines) have completely died back. This is usually after the first light frost. The skins will be set and thicker for storage.
* The Harvest Process:
1. Choose a dry day.
2. Use a digging fork, inserting it well away from the plant to avoid spearing tubers.
3. Gently lift the plant and sift through the soil with your hands for all potatoes.
4. Let them air-dry on the soil surface for a few hours, but not in direct sun.
Curing and Storage
Proper curing is essential for long-term storage.
1. Cure: Place undamaged potatoes in a single layer in a dark, well-ventilated, humid place (like a garage or basement) at 55-60°F for 10-14 days. This allows the skins to fully toughen and minor cuts to heal.
2. Store: After curing, brush off any dry soil (do not wash). Store them in breathable containers—like burlap sacks, paper bags, or cardboard boxes—in a completely dark, cool (38-40°F), and humid location. Check them periodically for any spoilers.
Frequently Asked Questions (FAQ)
Can I plant potatoes in July or August?
Yes, absolutely. July and August are common planting months for a fall potato harvest in many regions. Just use the frost-date calculation to find your perfect date.
What is the latest date to plant potatoes?
The latest date depends on your frost date and the variety’s maturity. As a general rule, you need at least 90 days before a hard freeze. In many areas, planting later than mid-August is risky.
How do I protect fall potatoes from early frost?
A light frost that kills the tops actually helps toughen potato skins. For an earlier, hard freeze forecast, you can protect plants overnight with row covers or old bedsheets. Mulching heavily also insulates the soil.
Can I use store-bought potatoes to plant?
It’s not recommended. Grocery store potatoes are often treated with sprout inhibitors and may carry diseases that can persist in your soil. Always use certified disease-free seed potatoes.
Why are my potato leaves turning yellow early?
In fall plantings, this is often natural maturation as days shorten. However, it could also indicate overwatering, a nutrient deficiency, or a disease like early blight. Review your watering practices and check for other symptoms.
Planting potatoes for a fall harvest is a rewarding way to extend your gardening season and enjoy fresh, homegrown produce well into autumn. With careful timing, the right varieties, and a little extra attention during the summer heat, you’ll be rewarded with a plentiful crop of earthy, flavorful tubers just as the weather turns cool.