Growth Stages of the Potato Plant

The potato (Solanum tuberosum) is a hearty crop that can be transformed into several yummy dishes. From mashed potatoes to hash browns to potato chips, most of us eat some form of potato every day!

Quality potatoes aren’t hard to find at your local grocery store. But they pale in comparison to those grown in a home garden. Not to mention, potatoes are one of the easiest vegetables to grow, with hardly any gardening experience at all.

In this article, I’ll explore several growth stages of the potato plant and explain what’s going on beneath the soil’s surface as your potatoes develop and mature into an edible harvest.

Conditions for Growing Potatoes

Though potato plants have a perennial life cycle, they are typically grown annually in the garden. This means that potatoes are planted and harvested all in the same growing season. Potatoes are versatile and hardy and can be grown in climates comparable to USDA Zone 3 to 10 with little fuss.

Plant your potatoes in a location with full sun exposure. Potato tubers develop for energy storage; the leaves will need as much sun as possible to create that energy. Most varieties grow up to 3 feet tall and wide. Avoid crowding your potatoes for a maximum harvest.

While potatoes enjoy a bit of sunlight, they don’t handle hot temperatures very well. Potatoes are best planted during the colder parts of the year. The ideal time to grow potatoes in your garden will depend on your local climate, with most potatoes starting in late spring, fall, or winter.

According to the University of Minnesota, potatoes are acidic soil with a pH of around 5.0 to 6.5. Your potatoes will need plenty of room to develop good tubers, so I recommend working the soil to a depth of at least 15 inches. This is also a good opportunity to amend the soil with aged compost or other organic matter.

Potatoes can easily be grown in containers or raised beds as well! Follow my advice above, choosing a vessel at least 15 inches deep so that the tubers have room to grow.

One last note on growing potatoes in the home garden: potatoes belong to the same family as other popular vegetables like tomatoes, peppers, and eggplant. As a result, they are vulnerable to the same pests and diseases.

Planting all these vegetables in one location — or planting them in the same spot year after year — is a lot like erecting a big banner telling your local pests and pathogens that dinner is ready! It’s good practice to rotate your garden so that you only grow potatoes and their relatives in the same soil once every three years.

Potato Plant Growth Rate

Root vegetables are interesting because we’re forced to guesstimate progress not based on the plant we want to harvest but on whatever part of the plant we see. When growing potatoes, we generally track the growth rate by looking at the shoots and leaves.

Most potato varieties achieve a mature height between 1 ½ and 3 feet throughout 90 to 120 days. This means you can expect an average growth rate of up to ½ inch per week.

Note, of course, that this growth is rarely linear. In my experience, the bulk of top growth occurs early in the potato life cycle. Once it reaches a good size, the potato redirects its energy to tuber development and flowering.

Growth Stages of Potato Plant

On average, potatoes need 90 to 120 days from planting to harvest. However, this rate varies from one type of potato to another. For example:

  • ‘Yukon Gold’ potatoes can be ready to dig up in as little as 75 days
  • ‘Russet Burbank’ potatoes sometimes need 135 days or more to mature
  • ‘Rocket’ is a very early-maturing variety that can be harvested within 60 to 70 days

Potatoes are often categorized by their growth rates. According to Oregon State University, common labels include early-maturing, mid-season, and late-maturing. Varieties that produce smaller tubers will usually mature quicker and vice-versa.

1. Planting Seed Potatoes

While you can start potatoes from seeds, you probably don’t want to. Seed-grown potatoes have unreliable genetics, so you never know what you’ll get. More often than not, the result is an unappetizing tuber at best.

The more common way to start potato plants is by using what are called ‘seed potatoes’. Seed potatoes are small tubers harvested in the previous year and saved for future planting. Unlike potatoes sold for eating, these tubers are NOT treated to prevent sprouting. (Though these treatments aren’t 100% effective — we’ve all found a sprouting potato in the pantry before!)

Seed potatoes from reputable growers are also monitored for diseases and pests, offering the home gardener a bit of extra peace of mind. 

Planting Seed Potatoes

You can plant seed potatoes directly in the ground when the soil is workable, and there’s no risk of frost. You can cut larger seed potatoes into segments — as long as each piece has at least one ‘eye’ to sprout from — to increase your harvest.

2. Sprouting

Potato tubers are covered in spots called eyes. These spots are auxiliary buds where cell division can occur to produce new sprouts from the tuber.

If your soil temperature is above 40 degrees F, seed potatoes should sprout in 14 to 28 days. Sometimes, seed potatoes sprout before you can get them in the ground. This is fine, but be sure to plant the tuber immediately.

Once the seed potato sprouts, the tuber will wither away. This is because the new potato plant uses the energy stored in the tuber to support its growth. Don’t worry! Many more tubers will eventually take its place.

3. Vegetative Growth

Seed potatoes may sprout single stems or several clumped close together. Either result is fine. Don’t be alarmed if some potatoes appear bushier than their neighbors.

Vegetative Growth

After the new potato plant develops several leaves, it can hit the ground running. For the next 60+ days, the potato will be hard at work producing shoots and leaves that it can use to photosynthesize. The energy from photosynthesis will be stored in the root system.

4. Tuber Development

As we make our way below ground to check in on the tubers, let’s take a quick detour to talk about the root system as a whole. 

Contrary to popular belief, potato tubers are not roots. The bulk of a potato plant’s root system comprises thin fibers that form a large net in the soil. These fibrous roots are responsible for taking in water, nutrients, and oxygen.

Tuber development normally begins 15 to 30 days after sprout emergence. At this stage, the tubers are only about the size of a small berry. Potato plants can produce up to 30 individual tubers, but most won’t develop past this point.

It takes 45 to 90 days post-emergence for the tubers to fill out. By this point, only about 5 to 15 tubers will be left. However, depending on the variety, they will likely be several inches in diameter.

5. Flowering

Flowering starts approximately 90 to 120 days after sprout emergence. Potato plants have small white, pink, or purple flowers reminiscent of other vegetables in the nightshade family. 

Flowering potato

Since potato tubers are not a fruit, flowering and pollination aren’t necessary for a good harvest. The appearance of flowers does, however, indicate that the tubers below ground are almost ready to dig up.

When to Harvest Potatoes

You’ll know it’s about time to harvest your potatoes when the leaves turn yellow and die back to the ground. It can take 10 to 20 days for the foliage to completely die back. The tubers are still maturing during this process, so wait until the visible part of the potato plant is entirely dead to dig them up.

For more potato life cycle articles, here’s an article about Sweet Potato Growth Stages that you may find interesting.

When to Harvest Potatoes

FAQs Growing Potatoes

Can you grow potatoes from seeds?

Yes, you can grow potatoes from normal seeds. The problem is that starting potatoes from seed takes a long time and doesn’t always offer the best results. Most growers opt to plant seed potatoes, which are small tubers that can produce new sprouts.

How many potatoes does one plant produce?

A single potato plant can produce up to 15 potatoes in one harvest! In most cases, however, potatoes will only produce 5 to 6 mature potatoes in one go. The remaining tubers will be small and underdeveloped.

Citations

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.