Potato Growth Stages: How Fast Do Potato Plants Grow?
Potatoes have many growth stages, leaving many gardeners curious at what point in the growth cycle their tomatoes currently sit. In this article, gardening expert Liessa Bowen examines the life cycle of garden grown potatoes, as well as how fast they grow and how soon you'll be able to harvest.
Potato (Solanum tuberosum) is an annual tuberous vegetable native to South America. There are over one hundred varieties of potatoes that you can grow in your home garden. Potatoes come in many colors, including white, yellow, red, purple, and blue, and they come in different sizes, from tiny orbs to fist-sized giants.
The most fun thing about growing your own potatoes is digging them up. Potatoes are especially fun to harvest with kids. You can plant one single potato, watch the plant grow vigorously, and then die back.
Now it looks like a pile of earth with a dead plant in the middle, but then you carefully dig up the earth around it and uncover 8 to 10 new potatoes! That’s a pretty good return on your initial investment.
If you think about growing potatoes and picture huge fields with row upon row of potato plants, don’t worry, you can grow as little as one potato plant or as many as you care to make room for. You can even grow potatoes in a container on your front patio or back deck. All you really need is a sunny spot and a plot of rich, loose, moist soil, and a potato to get you started growing.
Potato plants are very easy to grow in the home garden. As long as you have the right growing conditions, you can grow potatoes. Unlike most plants you can start from seed, most people start a potato plant from a potato (although it’s possible to grow some varieties from seed, too). Let’s dig deeper into the above-ground and below-ground stages of potato growing.
|Selecting Seed Potatoes
|– Grow potatoes from potatoes or from seed
– Select certified disease-free seed potatoes
– Buy quality seed potatoes, not grocery store potatoes
– Many varieties to choose from
|– Cool season crop
– Protect from hard frosts
– Start in spring for summer harvest
– Prep planting site
– Chit potatoes for planting, as needed
|– 2-4 weeks from planting to sprout
– Sprouts develop from potato eyes
– First leafy green growth
|– Plants grow larger, fuller
– 60-100 days of rapid growth
– Green leaves convert sunlight into energy
– Tubers start to form below ground
– Watch for pests on leaves
– Keep plot weeded
– Remove leafy debris
|– After sprouting, 15-30 days of tuber formation
– Plant creates all tubers for the season
– Very small, beanlike growths on roots
– Keep soil evenly moist
| – Flowers bloom 60-70 days after planting
– Blossoms are white or pale purple
– Plant nearing the end of life cycle
|– 10-20 days for final maturation
– Flowers die
– Top vegetation yellows and dies back
– Planting at the end of life cycle
– Tubers below ground finish maturing
|– 10-20 days for final maturation
– Flowers die
– Top vegetation yellows and gradually dies back
– Tubers below ground finish maturing
|– Up to 120 days after planting
– Harvest when vegetation dies back
– Loosen the soil around the plant with a garden fork
– Harvest potatoes
– Store in a cool, dark, well-ventilated place
– Store for up to 8 months
Depending on the variety, it takes a potato plant anywhere from 60 to 120 days from planting to harvest. All potato plants benefit from similar growing conditions. If you want your potato crop to thrive, you must provide the best growing conditions possible. Be especially aware of soil moisture and nutrition.
|Full sun, at least 6 or more hours of direct sunlight per day
|Warm but not hot. The ideal temperature range to grow potatoes is between 65°F and 80°F during the day and 55°F to 65°F at night
|Consistently moist, but not wet
|Somewhat acidic, between 5.0 and 6.0
|Fertilize 2 weeks after planting and again 4 weeks after that. Use a balanced slow-release fertilizer and follow the directions on the package.
|Remove weeds regularly. Mulch around plants to help keep weeds away.
Potatoes are extremely easy to grow from seed potatoes. These are not potato seeds but certified disease-free potatoes that will grow the healthiest crop of new potatoes.
It is technically possible to grow a potato from seed (Clancy is a fast-growing variety for those who want to try from actual seed), but this process is more time-consuming than buying seed potatoes. For this reason, most suppliers sell seed potatoes, not potato seeds.
But why would you buy seed potatoes rather than just fresh-eating potatoes? When you buy potatoes from the grocery store, they frequently are treated with a growth inhibitor to delay sprouting. They are also not guaranteed to be disease-free and may carry fungal spores. These may introduce a variety of unpleasant potato diseases to your garden that can affect your potato crop and other related crops like tomatoes and peppers.
If you order seed potatoes online, buy from a reputable company, and they will send your seed potatoes close to planting time. If you buy seed potatoes from a garden center, select firm, healthy, and unblemished potatoes. It’s okay if they already have sprouts, but don’t buy any potatoes with mushy spots, gashes, or mold.
Unlike buying seeds, seed potatoes do not last for several years and will need to be planted within a few weeks. If you need to store them for a bit longer, keep them in a cool, dark place to prevent them from sprouting. The temperature should be between 45°F and 50°F with relatively high humidity and good ventilation to prevent rot.
Potatoes are generally considered a cool-season crop. They are most commonly grown in the spring for summer harvest, but you can also plant them in the summer for fall harvest.
For spring planting, get your potatoes in the ground any time after the danger of major frost. Potatoes will tolerate a brief light frost, but plan to cover and protect your plants from anything more. For a fall harvest, try planting them mid-summer.
Before you plant, prepare your planting site. Potatoes need full sun with at least 6 hours of direct sunlight per day. The soil should be loose and well-drained. If the soil stays too wet, the potatoes will quickly rot. Cultivate the soil 8 to 10 inches deep. Work in some nutritious organic matter like aged manure or compost to enrich the soil and feed the potatoes as they develop.
You may also need to prepare your potatoes in advance. Small seed potatoes can be planted whole, just as they are. Larger potatoes can be cut in half or quartered, provided each section has at least one eye and preferably 2-3 eyes from which to sprout. Use a clean knife and work on a clean surface while doing this.
Let your cut pieces air dry for 2 or 3 days in a location with good airflow but out of the sun. The cut edge will harden and become a bit leathery to the touch. This drying step is crucial; your potatoes may rot when planted if they’re still fresh-cut! Your potatoes are ready to plant once the cut edges have dried and formed a skin.
Potatoes can be planted in rows, hills, or large containers. Dig a hole or trench 4 to 6 inches deep and lay your potatoes with their eyes facing up in the hole. Give them some space so they are between 8 and 12 inches apart. Cover them completely with several inches of soil. Consider adding a layer of straw mulch on top to help maintain soil moisture and keep potatoes protected from sunlight.
Now that your potatoes are planted, your next step is to wait for the first sprouts. While you’re waiting, keep the soil moist.
Each eye on the seed potato has the ability to become a new vegetative sprout. As they start to sprout, they look like little specks of fresh white or pink growths emerging from the potato.
It is quite common for a potato to start sprouting before it is planted in the ground. If this happens, don’t worry! Enjoy having a clear view of the new sprouts, but try to plant them soon so they can grow in the ground. If you planted a seed potato that hasn’t yet sprouted, you won’t see this stage because it is happening entirely underground.
You will probably have to wait 2 to 4 weeks for the first sprouts to emerge from the soil. Above each potato you planted, keep watch for the first sprouts to break the soil surface. You may notice just a single clump of greenery or several clumps in close proximity.
The tuberous potato you planted will become the primary energy source for the new plant. As the vegetation grows, the seed potato will shrivel and wither away. The plant will form new roots and fresh green vegetation and will start to develop tiny new potatoes.
During this rapid vegetative growth phase, your plant will quickly grow larger and bushier. You may have either a single stem or multiple stems growing over each potato. You won’t need to do any thinning at all. Just let each stem grow freely. They will work hard both above and below the soil surface to produce the next crop.
Once you see the first green sprouts, it can take 60 to 100 days for a plant to reach maturity. During this time, the plant will be growing rapidly. The bulk of the vegetative growth happens between the sprouting and flowering phases. After flowering, the plant starts to die back, and the vegetative growth phase has ended.
Foliage Pests and Diseases
Potato foliage is susceptible to numerous pests and diseases. Fortunately, the home gardener won’t typically have as many issues as a large potato farm, but you should still be aware of some of the most common above-ground potato pests.
- Green body with small spots
- Leafhoppers feed on the undersides of leaves
- Cause brown spots, yellowing, and wilting of leaves
- Plant pest-resistant potato varieties
- Use a hard jet of water spray to remove nymphs
- Insecticidal soap may be used if infestation continues
- Use insecticides with caution
Colorado Potato Beetle
- Oval beetle, yellowish body with black stripes and spots
- Adults and larvae chew holes in leaves
- Heavy infestations can kill plants
- Hand-pick and kill adults and larvae
- Tiny black or brownish beetles
- Feed on leaves, creating many small holes
- Can transmit blight
- Keep the garden area free of weeds and leafy debris
- Use insecticides with caution
|Potatoes, tomatoes, and peppers attract many of the same pests. Do not plant these crops in the same location in successive years. Crop rotation will help prevent pests and diseases from accumulating in the same place.
|Keep soil uniformly moist but not wet. Try to avoid large fluctuations between wet and dry soil. Soggy soil will cause potatoes to rot.
|Check your potato plants regularly. Be alert for pests and changes to your plants’ health. Identify and treat problems promptly.
|Keep the area clean
|Keep weeds, infected plants, and leafy debris away from healthy plants. These can all harbor pests that attack and feed upon potato plants.
|Use insecticides with caution. Start with less-damaging methods like hard water sprays or less-damaging options like insecticidal soaps or horticultural oils, and only gradually increase the potency if infestation continues. Treat only infected plants. While potatoes don’t rely on pollinators to produce a crop, many other plants do.
|Companion plants can benefit potatoes by improving soil quality and repelling pests. Some good companion plants for potatoes include beans, cabbage, carrots, corn, cucumber, garlic, lettuce, and peas.
From 15 to 30 days after sprouts appear, potato roots have reached a phase where they begin to produce new tubers. Every new tuber your plant produces will be created during this phase!
They start out looking like little bean-sized lumps along the root system. After this, the plant devotes its energy to each of these existing tubers and grows them larger.
Above ground, you will see the vegetative growth stage, where the plant sprouts new leaves and grows larger and taller. Below ground, the plant will attempt to produce buds for as many as 20 or 30 tubers, but not all of these will reach maturity.
From 5 to 15 tubers on each plant will reach maturity, depending on growing conditions, soil moisture, and available nutrients.
This is an especially important phase that directly affects your final harvest. During this time, ensure your plant has the ideal conditions, especially consistent soil moisture, to help ensure an excellent harvest later on.
Highly variable weather and moisture during this time can cause your plants to have poor production rates, and few potatoes will develop.
The tuber growth stage, also known as tuber bulking, is when your potato tubers grow larger. Between 45 and 90 days after the first sprouts emerge, the tubers produced during the tuber formation stage will grow from tiny buds to full-size potatoes.
The plants won’t make new tubers, but the existing tubers will get bigger and bigger, storing nutrients and carbohydrate energy. They won’t reach their maximum size until the flowering stage when the plant reaches maturity.
You won’t be able to see the tuber growth because it all happens underground. But you should be aware of what’s happening because you don’t want those tubers exposed at the soil’s surface, or they will turn green and bitter.
To help keep the tubers growing entirely underground, potato gardeners often use a practice called hilling. In hilling, you add fresh soil or hay by mounding it along the sides of the plants every few weeks. This prevents tubers from being exposed to sunlight and has the added benefit of helping control weeds.
During this phase, you may observe that the plant seems to have stopped growing, and the leaves will start to turn yellow. This is an above-ground sign that the plant is diverting all its remaining energy into growing the below-ground tubers to their final size. Your potatoes will be largest if you have ideal growing conditions, including bright sunlight, moist soil, plenty of space between plants, and high-quality soil nutrients.
It’s important to maintain even watering during this time. Ideally, you will want to keep the soil uniformly moist. Uneven watering can cause uneven tuber development, cracking, and splitting. It can also cause your potatoes to have hollow, airy pockets in the centers when they should be thoroughly solid.
- Whitish or brownish caterpillars, the larvae of the potato tuber moth
- Caterpillars bore into potato tubers causing extensive damage
- The larvae also eat holes in potato leaves
- Primarily affects tubers closest to the soil surface
- Keep potatoes completely underground to avoid tuberworm damage
- White or tan larvae of a click beetle
- Wireworms chew holes in the roots and tubers
- Rotate crops to reduce exposure
- White grub-like beetle larvae
- Grubs chew stems, roots, and tubers of many crops
- Underground damage can occur before the above-ground plant shows symptoms
- Crop rotation reduces access
- Bacterial infection affecting tubers
- Inflammation of the outer skin of a potato
- Use disease-resistant seed potatoes
- Grow in acidic soil
Bacterial Soft Rot
- Common bacterial infection
- Tubers develop numerous soft spots
- Don’t let potatoes sit in wet soil
- Cure (dry) tubers thoroughly before storage
The flowering stage happens towards the end of tuber growth and the beginning of maturation. Potatoes are flowering plants that bloom about 60 to 70 days after planting. The flowers aren’t, of course, where the potato tubers come from. But this is still an essential stage of the growth cycle of the potato plant. As a bonus, the flowers are small but showy and attract some pollinators.
Potato flowers are typically white or pale purple with somewhat prominent yellow anthers. Some potato varieties have darker pink flowers or dark red or purple anthers. The flowers each last just a few days and signal that the plant is near the end of its life cycle.
The final stage before harvesting your potatoes is maturation. This phase lasts approximately 10 to 20 days. During this phase, the leafy green parts of the plant turn yellow and die off.
As the above-ground part of the plant dies, the potatoes are still safe underground, finishing their growth process. At this point, they will be as large as they can be. When the top part of the plant has completely died back, it’s time to harvest.
You’ve waited for as many as 120 days for this moment, and now comes the fun part. Are you ready to dig some potatoes? Put on your work gloves and grab a garden fork. You’ll probably also want to bring a sturdy basket to put your potatoes in.
Your harvest times might differ slightly depending on the variety of potatoes you planted. Baby potatoes can be harvested 2 or 3 weeks after your plants have finished flowering. A more mature potato you want to bake or store for a long time will need additional time in the ground. Wait until the plant foliage has completely died back before digging for fully mature potatoes.
When ready to dig your potatoes, use a sturdy garden fork to carefully loosen the soil around the place where the plant was growing. Don’t dig close to the main stem, or you will end up piercing through many tubers. As you turn the soil, you will see a mass of potatoes around the base of each plant. Carefully remove the potatoes from the earth.
If the weather is warm and dry, leave them to dry in the sun for a few hours. This allows the skins to dry and cure, making them more durable for storage.
Once dry, bring them in and store them in a cool (45°F to 50°F) location for up to 8 months. Do not store them in an airtight container; they need good ventilation to prevent rotting. If you store them in a warm or bright location, they will start to sprout again. Any potato with soft spots or damage to the skin should be removed and eaten quickly, or it will rot.
Potatoes are a fun crop to grow. You may find only 3 or 4 potato varieties at your local grocery store, all of which are optimized for long storage over flavor, but you can grow over one hundred unique varieties at home! Start some seed potatoes in the spring and harvest them in mid-summer.
Be sure to buy and plant only certified disease-free seed potatoes. Give your plants plenty of sunlight, moist soil, and hearty nutrition. Watch for mid-season pests, and keep those potatoes underground until they are ready to harvest. Then the best part is harvesting your very own homegrown crop of potatoes. How will you cook your potatoes for dinner tonight?