When Is It Too Late To Plant Potatoes

If you’ve found yourself staring at a bag of seed potatoes in late spring or even early summer, you’re probably wondering when is it too late to plant potatoes. The good news is, with the right approach, you can often push the planting window further than you think. This guide will help you understand the timing, risks, and techniques for late planting so you can still get a harvest.

Potatoes are a cool-season crop, and their ideal planting time is a few weeks before your last expected spring frost. But gardening is rarely about perfect timing. Life gets busy, weather is unpredictable, and sometimes we just miss the window. The real answer to “too late” depends on your local climate, the potato variety, and your willingness to adapt.

Let’s break down the core question. For most regions, planting potatoes is considered too late when the days to maturity of your chosen variety would push your harvest date into the first hard frosts of fall. Potatoes need 75 to 120+ frost-free days to develop good-sized tubers, and their foliage cannot survive a freeze.

Understanding the “Days to Maturity” Clock

Every potato variety has a days-to-maturity range. This is counted from planting to when the plants naturally die back, signaling the tubers are ready.

Early Season (70-90 days): Like ‘Yukon Gold’ or ‘Red Norland’. These are your best bet for late planting.
Mid Season (90-110 days): Like ‘Kennebec’ or ‘Purple Majesty’. Possible for late planting if you have a long fall.
Late Season (110-140 days): Like ‘Russet Burbank’. These are risky for late planting in most areas.

You need to count backward from your area’s average first fall frost date. Find your frost date, subtract the days to maturity, and that’s your last ideal planting date. Planting a week or two after this date is often worth a try, especially with early varieties.

The Real Cut-Off: Soil Temperature & Daylight

Beyond frost dates, two hidden factors matter. First, potato tubers develop best when soil temperatures are between 60°F and 70°F. If you plant in mid-summer when soil is very hot (over 80°F), tuber formation can stall. Second, potato plants prefer lengthening days of spring. Planting in summer’s shortening days can sometimes result in smaller plants.

Regional Late Planting Windows

Here’s a rough guide for the absolute last-chance planting times. These assume you use early-season varieties.

Northern Climates (Short Season): Aim to plant by late June at the very latest. Early July is pushing it, but you might get “new” baby potatoes.
Mid-Latitude Climates: You often have until mid-July for a decent late crop.
Southern Climates: You can actually plant a late summer crop for fall harvest! Plant in late July or August, as soil cools from peak summer heat.

How to Successfully Plant Potatoes Late

If you’ve decided to go for it, these steps will maximize your chances for success. The strategy shifts from spring planting.

1. Choose the Right Variety

This is non-negotiable. Select an early or mid-season variety. Skip the long-season baking potatoes this time. Look for seed potatoes labeled as “early” (like Irish Cobbler) or “early mid-season” (like Yukon Gold).

2. Pre-sprout Your Seed Potatoes

Also called “chitting,” this gives you a head start. Place your seed potatoes in a bright, cool spot for 1-2 weeks before planting. Short, sturdy sprouts will form. This can shave 1-2 weeks off the time in the ground, a huge advantage when racing frost.

3. Plant Smart for Faster Growth

You want to create ideal, warm conditions for quick emergence.

Soil Prep: Work in compost for nutrients and ensure perfect drainage. Water the trench before planting if soil is dry.
Planting Depth: Plant shallower than spring potatoes—about 3-4 inches deep. This allows the sprouts to reach the surface faster.
Watering: Keep the soil consistently moist (not soggy) from day one. Summer heat can dry soil quickly.

4. Focus on Tuber Development

Once plants are up, your goal is to channel energy into the tubers.

Hilling: Hill soil around the stems as the plants grow, but do it earlier than you normally would. This protects developing tubers from sunlight and keeps the root zone cool.
Mulching is Key: After hilling, apply a thick layer of straw or shredded leaves. This mulch keeps soil temperatures lower, conserves moisture, and suppresses weeds. It’s critical for late plantings.
Fertilizing: Use a balanced fertilizer at planting. Switch to a low-nitrogen, higher-potassium fertilizer once plants flower to boost tuber size.

What to Expect from a Late-Planted Crop

Manage your expectations. A late-planted crop will often yield smaller tubers and a lighter harvest per plant compared to a spring-planted one. However, the potatoes you do get will be perfectly edible and delicious. Many gardeners find that late-planted potatoes have fewer pest problems, as they miss the peak lifecycle of some insects.

The foliage may not die back naturally before frost. You’ll likely need to harvest based on the calendar or when frost threatens, even if the plants are still green.

The Signs It’s Truly Too Late

Sometimes, it’s better to save your seed potatoes for next year. Here are signs you should wait.

Your calculated harvest date is a full month after your average first frost.
You only have late-season varieties available.
The soil is bone-dry and very hot, with no rain or cool weather in the forcast.
You’re in a region where fall brings prolonged, cold rains that would rot tubers before they mature.

Alternative: Grow in Containers

If your garden soil is too hot or space is limited, container planting is a fantastic option for late potatoes. Use a large pot or grow bag. You can control the soil temperature better by moving the container to a partly shaded spot during the hottest part of the summer. Containers also avoid issues with soil-borne diseases that might be building up in your garden beds.

Harvesting Your Late Crop

Keep a very close eye on the weather. If an early, hard frost is predicted, you have two options:

Harvest Immediately Before Frost: Carefully dig your potatoes. They will be thin-skinned and won’t store as long as fully mature potatoes, so plan to eat them soon.
Protect the Plants: If it’s just a light frost, cover the plants with row cover or old blankets overnight. This can buy you an extra week or two of growing time, which is very valuable.

After a frost kills the foliage, dig your potatoes within a week or two to prevent rot. Let them cure in a dry, shaded place for a few hours before storing.

FAQ: Late Potato Planting

Can I plant potatoes in July?

Yes, in many areas you can plant potatoes in July. Use early-season varieties and be prepared to protect them from fall frosts. In hot climates, July planting for a fall harvest is common practice.

What happens if you plant potatoes too late?

If planted to late, the plants may not have enough time to form sizable tubers before frost kills the foliage. You might only get very small, marble-sized potatoes, or in the worst case, no tubers at all.

Is August too late for planting potatoes?

For most northern climates, August is too late for a meaningful harvest. However, in mild-winter climates with long autumns, August planting can yield a small crop of new potatoes by Thanksgiving.

Can I use store-bought potatoes to plant late?

It’s not recommended. Store-bought potatoes are often treated with sprout inhibitors and may carry disease. For a late planting where conditions are already challenging, start with certified disease-free seed potatoes to give yourself the best chance.

How do I protect late potatoes from frost?

Use floating row covers or thick mulch like straw around the base of the plants. For a predicted hard freeze, you can even temporarily cover plants with cardboard boxes or buckets overnight. Every frost-free day helps.

So, when is it too late to plant potatoes? The calendar gives a guideline, but your local conditions and willingness to adapt are what really count. Don’t be afraid to try a late planting with early varieties. Even if your harvest is smaller, the joy of pulling homegrown potatoes from the ground is always worth the effort. Just remember to adjust your methods, keep them watered and cool, and watch the sky as fall approaches.