The Ultimate Guide to Planting Potatoes at the Right Time

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Knowing when to plant potatoes in containers can prevent frustrations and crop losses, extend the growing season, and maximize yields. 

Potato (Solanum tuberosum) is a cool-season crop that does best when temperatures are in the lower sixties (15.5 – 18.3°C). Potato plants must have consistent access to water during tuber formation and tuber growth periods.

Table of Contents

Quick Potato Growing Tips

Like all photoautotrophs, potatoes need light, CO₂ and water to feed themselves. Healthy foliage helps boost root health, providing better access to water and nutrients essential to general plant health and resilience.

Potato plants are naturally perennial but are grown annually to capitalize on their nutritious tubers. The tubers serve as natural food and water storage to kickstart post-dormancy growth. 

Harvested tubers (potatoes) can serve as a source for new growth. Still, it is essential to preserve the tubers’ integrity and health and manage their emergence from dormancy for optimal productivity as ‘seed’ potatoes.

12 Tips to Grow Potatoes Successfully

1. The potato plant has a medium-depth root system that reaches up to 24 inches (60 cm) below the ground. Give it room to grow.
2. Potato tubers are not roots but distended stems that grow below the ground on the ends of rhizomes. 
3. Potatoes are grown from tubers or tuber cuttings called seed potatoes. Using healthy or disease-free certified seed potatoes can benefit production significantly. Plants do produce potato seeds, but these are generally sterile or unpredictable.
4. Pre-water your soil before planting seed potatoes, and then avoid overwatering until plant emergence (two to three weeks). The planted tuber has sufficient moisture and energy to initiate growth (this is why seed potato pieces should weigh between 1.5 and 2 ounces (42 and 57g). Lower soil moisture levels during this time will reduce pathogen risks.
5. Plant seed potatoes deep enough for part of the stem to be underground as the potatoes grow. Ensure that the seed pieces are not colder than the soil temperature (which should be around 50°F/10°C in the top foot/30cm).
6. Increase the underground portion of the stem by hilling, i.e., covering the green stem with soil as the plant grows. This only works for late-season (indeterminate) potatoes.
7. Only cover a third of the exposed stem when hilling, leaving enough foliage for optimal photosynthesis.
8. For mid and late-season (indeterminate) potatoes, tuber formation occurs in the first third of the total growth (40 days of 120). Ensure the plant’s foliage health is prioritized during this time, increasing soil moisture incrementally until the plant starts to bloom, a sign that tuber expansion has commenced.
9. Tuber expansion starts at the midpoint (60 days after planting), when plant health and water availability need to be prioritized. 
10. Leave flowers on the plant until tomato-like fruit starts forming, and then remove the fruit to channel energy to tuber expansion. 
11. You can cut watering the plant once foliage starts declining, a sign that the tubers are ready for harvesting.
12. Start harvesting for baby or new potatoes when at least 50% of the foliage has died.

Keep reading for more tips on planting, growing, and harvesting potatoes, focusing on the advantages of growing potatoes in containers or unique potato growing bags.

How Long Does it Take to Grow Potatoes?

Different potato varieties take an additional amount of days to mature. On average, potato plants mature between three and four months. Depending on the type, crops can take 10 to 20 weeks to grow.

Potatoes are often grouped by the average length of their growing season

• Early cultivars take between 72 and 80 days. Early potatoes are generally grown in early spring. 
• Mid-season cultivars take between 80 and 100 days
• Late-season cultivars mature in 100 to 140 days

The advantage of living in cooler areas (where day temperatures seldom exceed 80°F/26.7C, is that potato growing and harvesting can be spread out by staggered planting times or the use of all three cultivar types started simultaneously.

Depending on where your garden is, you can grow potatoes in spring, summer, or fall crop. 

What is The Best Month to Plant Potatoes?

When to plant potatoes depends on where you live. I have climate.gov’s interactive map showing the average date of last spring freeze across the United States. The map ranges from Jan 16 to May 31 across the country, quite a range.

Typically, you want to plant your potatoes once the soil temperature is above 45°F/7.2°C and with enough growing time to mature (70 to 120 days after planting) before the ground freezes in winter. That is quite a scope, but don’t be surprised by the last frost.

Potatoes in containers have an advantage in that they can be moved indoors when the weather turns nasty (hot or cold).

The three biggest potato-producing states in 2022 were:

1. Idaho – last spring froze in late May. Most Idaho potatoes come from the Snake River Plain, Zone 6a.
2. Washington – last spring freeze ranges from mid-March to late May. Much of Washington State is in USDA Hardiness Zone 6b and 7a (-5 to 5°F/-20.6 to -15°C).
3. Wisconsin –  last spring froze in late April. Wisconsin, like Idaho, has a wide range of temperature variances, which include Zones 6b and 7a.

All three of these states are in the far North, where ambient temperatures are low and days shorter.

The advantage of growing potatoes in containers is that you can control soil temperatures better, allowing you to plant potatoes even while the garden soil is frozen, and garden potatoes would be impossible.

Use the CLIMATE.GOV’s link provided at the beginning of this section to establish the last spring frost date for your region. Once the last frost has passed, check your soil temperature and wait until it reaches at least 50°F/10°C. 

We’re less worried about the winter’s first frost as our potato plant’s foliage should already be dead, and all we need to avoid is having spuds in the ground when the soil freezes. Unlike turnips, potatoes are not improved by harvesting them after a hard frost.  

When to Plant Potatoes: Early, Mid-Season, and Late

The best planting time for planting potatoes is as early as possible, and cooler temperatures are better for the initial growth of freshly planted seed potatoes. Remember that potatoes are perennial, and the tubers serve as a resource reservoir to sustain the initial growth after winter dormancy.

In their natural habitat, the Peruvian mountains, wild potatoes will emerge from dormancy when the soil temperature is above 40°F/4.4°C. This is when potatoes have minor threats from pathogens that only appear once the plant is about eight weeks old.

Many gardeners start their first potato crops indoors about two weeks before the last frost, marking the start of spring. It is common for groups to be grown right up to just before Christmas.

Growing Early Potatoes (Determinate Potatoes)

Potatoes are hugely versatile and staple ingredients of many meals in one form or another—boiled, mashed, chipped, or baked. They’re classified as earlies, second earlies, or main crops.

Early varieties are ready to harvest much sooner than main crops and are new potatoes. Main crop varieties are much longer in the ground and produce larger potatoes.

On early potatoes, rub off the weakest shoots leaving four per tuber. The first earlies should be planted around late March, and the second earlies, early to mid-April.

The traditional planting method is to dig a narrow trench 6 inches (15 cm) deep. Rows should be two feet apart (60 cm), and the early seed tubers should ideally be spaced a foot (30 cm) apart in each row. 

When growth emerges, start the process of hilling up your potato plant. Wait until the stems are about four to 6 inches (10 to 15 cm) high, and drag the soil up to the stems. Cover only a third of the stem. 

As the stems grow, repeat the process. The final height of the ridge would be about 10 to 12 inches (20 to 30 cm). 

If your gardening space is limited, you can grow small crops of potatoes and deep containers like grow bags or buckets.

Fill the bottom 6 inches (15 cm) container with potting compost and place the potato seed on the surfaces. Use one tuber for every 12-inch-diameter (30 cm) pot. As the new stems grow, add compost until the container is full. 

First, potatoes should be ready to lift in June and July, and second, early in July and August.

You can harvest earlies about 10 to 12 weeks after planting. This variety will produce new or baby potatoes ideal for boiling or steaming. Second earlies are excellent for general use, with broad types making delicious salad potatoes.

10 Tips on Producing Seed Potatoes

1. Choose seed potatoes certified as disease-free seed
2. If you can access them, choose single drops, small whole tubers less than 2 oz. in weight that can be planted whole.
3. Pre-sprout larger whole potatoes only if they have not been de-sprouted. 
4. Use a reasonably sized potato seed complete, ideally between 1½ and 2 ounces (42 to 57g). It should be uniformly cut with minimal scars and used as soon as the scars 
5. Seed potatoes can be bought from late winter onwards, significantly earlier, and it’s essential to chit the seed potatoes before planting. This means allowing them to start sprouting shoots. 
6. If cutting seed potatoes, use a knife dipped into a 10% Clorox solution between cutting washed tubers.
7. Stand them in rows, and ends up in egg boxes (or similar) in a light frost-free place. The potatoes are ready to plant when the shoots are about an inch long (3 cm). 
8. As soon as a seed potato is cut, it becomes less reliable to produce abundant tubers. Mishandled, older, scuffed potatoes will produce ample foliage but few tubers. 
9. Fresher, healthier, care-for seed potatoes take longer to emerge but produce better harvests. 
10. Do not pretreat seed potatoes chemically unless they are going to be planted in soil that is generally very wet.

How Long Should Potatoes be Chitted For?

Chitting is a term used to pre-sprout or green-sprout a seed potato. How long chitting takes depends on the temperature, night temperatures, light availability, and ethylene’s presence.

• Ambient temperatures should be kept in the upper sixties degrees Fahrenheit.
• Night temperatures should drop to below 60°F/15.6°C.
• Daylight must be bright direct sunlight (or the equivalent) for around six hours.
• If other ripe fruit, like bananas, are available, they emit a ripening hormone, ethylene, that triggers seed chitting.

How Do You Plant Potatoes in a Container?

If your gardening space is limited, you can grow small crops of potatoes and deep containers like grow bags or buckets.

1. Fill the container’s bottom four to six 6 inches (10 – 15 cm) with potting compost.
2. Mix half a cup of bone, fish, and blood meal.
3. Use one tuber for every 12-inch-diameter (30 cm) pot. 
4. Place the potato seeds on the surface, chits facing upwards. Lightly press them into the soil so that there is good soil contact.
5. Cover the seeds with about six inches of potting compost, leaving about an inch (2.5cm) on top for a hay mulch.

When to plant Potatoes in Containers

You plant potatoes indoors about two to three weeks before the last frost date. Ensure that the soil temperature stays around 50°F/10°C during that time.

When Can I Harvest Potatoes?

First, potatoes should be ready in June and July, and second early in July and August.

You can harvest earlies about 10 to 12 weeks after planting. This variety will produce new or baby potatoes ideal for boiling or steaming. Second earlies are excellent for general use, with many types making perfect salad potatoes.

FAQs on The Ultimate Guide to Planting Potatoes at the Right Time

In Conclusion

When to plant potatoes depends on local temperatures throughout the growing season. Once seed potatoes emerge, and foliage is established, watering becomes more essential than temperatures. Container gardening allows you to start much earlier than garden soils would allow.

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