Why Are My Potatoes So Small? | Top 5 Causes and Solutions

If you love potatoes, growing them yourself is definitely a great idea. There’s nothing quite like growing your own vegetables and eating them fresh out of the garden. Sometimes potatoes don’t grow like you want them to, and one of the most common problems is when they come out too small.

There are lots of reasons why your potatoes might be small, including a nutrient deficiency, lack of sunlight, high temperatures, harvesting ground too early, and improper watering.

This article will explore why potatoes will stay small, how to grow them bigger at home and some easy tips for a great tasting crop.

Why Potatoes stay small

Here are the top reasons why potatoes stay small when you are growing them at home and some easy tips to grow them bigger.

1. Nutrient deficiency

Small potatoes can be caused by a lack of nutrients. If they are not getting enough nutrients or minerals to grow properly they will stay small.

For very poor soils, dig through aged compost and small amounts of aged cow manure. Small amounts of balanced balanced fertilizer, such as 10-10-10, can help because it has the three most important nutrients for plants – nitrogen, phosphorus, and potassium, or NPK.

Check the pH balance of the soil, which should be between 6.0 and 6.5.

2. Crowding

If you know your soil is healthy and the pH level is correct but you’re still getting small potatoes, it could be because they are too crowded. When potatoes are planted right next to one another, they have to compete for both water and nutrients.

Plant seed potatoes at least nine inches apart for smaller (new) potatoes, and 20 inches apart to grow potatoes as large as possible. Plant them in small mounds to help to give them more room and to increase drainage to prevent rot.

3. Not enough sunlight

Just like most vegetables, potatoes need lots of sunlight to grow nice and large. In most cases, this means they need to get six to eight hours of direct sunlight every single day, and maybe even more. Less sunlight means less photosynthesis and less energy from the plant.

When potatoes get enough sunlight, the vines and leaves of the plants can produce enough energy, which means the tubers will get the starches they need to grow. Without this, you’ll get smaller potatoes and sometimes even no potatoes at all.

Even if the plants get enough water and nutrients, they won’t grow to the right size if they don’t get lots of sun throughout most of the day. Make sure there are no plants nearby that can block the sun from getting to them, including taller plants such as tomatoes. After all, potato plants should never be in the shade. Remember: lots of sunlight every day is what potatoes need!

For more on how to plant potatoes, check out this video.

3. Too hot outside

Lots of sunlight is a must for growing potatoes, but keep in mind that potatoes are still a cool weather crop. If the temperature get too high, it can affect both how many potatoes grow and how how big they are.

It’s the temperature of the soil that counts, and it shouldn’t get above 80 degrees Fahrenheit. To keep the potatoes in the sunlight and the soil at the right temperature, the following tips can help:

  • Irrigate the plants with cold water to cool down the soil
  • Consider attaching pieces of cloth or row covers to the stakes so the potatoes are protected during the hottest part of the day

The balance between the potatoes getting enough sun but the soil not getting above 80 degrees Fahrenheit is a delicate one, but it is not impossible to achieve. Just watch the soil and maybe even test it periodically to make sure it is warm and damp but not too hot.

4. Harvesting the tubers too early

If you harvest your potatoes too early, the plant doesn’t send enough energy to the tubers themselves, and this keeps the potatoes smaller than normal. If you’re curious about whether or not it’s time to harvest your potatoes, keep in mind that if the potato skins rub away easily, they are not ready to be harvested.

New potatoes which are naturally mild tasting and smaller are usually harvested two to three weeks after the plants stop their flowering.

For other potatoes, you should wait two to three weeks after you’ve noticed that the foliage has died. This means the plant will have enough time to send energy, that is, starches to the tubers. If your potato vines fall over and turn yellow, it is definitely time for the vegetable to be harvested.

5. Improper Watering

Without the right amount of water, potatoes will not grow large. The soil has to stay moist throughout the growing season or the plants can wilt and die. Keep in mind that if you have sandy soil, it will drain faster than other types of soil.

With sandy soil, you’ll want to add some organic material to keep it damp enough. A compost made out of grass, leaves, and vegetable scraps is a perfect suggestion and will work wonders keeping the soil as moist as it needs to be for your potato plants to grow.

You can also add mulch to the soil to keep it nice and damp. Mulch is excellent for growing potatoes, and it also cools down the soil and helps prevent weeds. You can even use materials in your mulch such as wood chips, and if you pile the mulch up around the base of the plants (known as hilling), the plants will stay even more moist.


Growing potatoes is not complicated, but there are still certain things to do and things to avoid if you want them to grow to a good size. Large potatoes are great to eat and you can do so many things with them. Giving them enough sunlight, making sure the soil doesn’t get too hot, and giving them the nutrients they need is a great place to start.

All of these tips will help you to get nice, big potatoes ready to harvest and turn into a delicious dish.

Happy growing.