How to successfully grow great potatoes

Potatoes are the most fun vegetable to grow. Why? Well, the seeds are actual potato pieces and thus are easy to handle. Second, it’s so much fun to dig up potatoes when they are mature. Third, potatoes are easy to grow. Fourth, a pound of seed potatoes will yield a significant bounty of potatoes. Now, let’s take a closer look at the requirements for how to successfully grow great potatoes.

Potatoes are members of the Solanaceae nightshade family of vegetables, including tomatoes, peppers, and eggplant. However, unlike their family members, potatoes are a cool-season vegetable. Thus, potatoes are planted earlier in the growing season.

Estimated reading time: 11 minutes

Potato Characteristics

Before we discuss growing potatoes, let’s look at the characteristics of potatoes.

1. Color – There are many different colors of potatoes both inside and out. These include red, brown, and white.
   • Russet potatoes have brown skins and are good for baking, frying, and mashing. Most popular type grown in the US.
   • Red potatoes can have white, yellow, or red skins and are good for boiling.
   • White potatoes with white or yellow skin are best for boiling and frying.
   • Yellow potatoes are good for boiling and frying
   • Purple colored potatoes are good for baking and frying
   • Fingerlings are small varieties that are long and narrow.
2. Growth – Potatoes grow underground and are called tubers. The tubers are an enlarged stem and new tubers grow close to their original potato seed. Potatoes are further classified as either early maturing varieties or mid to late maturing varieties.
3. Nutrition – potatoes are a good source of vitamin C, potassium, fiber, and protein. The skin of the potato contains most of the fiber as well as nutrients. In addition, potatoes are essentially fat-free and an average-sized potato contains about 75 calories (similar to an apple).
4. Potatoes are the number one non-grain crop grown in the world. Americans eat an average of 125 pounds of potatoes a year.

Growing from Seed Potatoes

To ensure success, always start with seed potatoes and purchase from a reputable seed company or garden center. What is a seed potato? It’s a potato that is used to grow more potatoes. Further, seed potatoes are grown to be free of disease and pests. It is not advisable to plant potatoes purchased at the supermarket. Grocery store potatoes are routinely sprayed with a chemical to discourage sprouting. Even organic potatoes can be problematic because they are not screened for disease.

The seed company I use for my seed potatoes, High Mowing Organic Seed Company, ships the seed potatoes at the ideal time for planting based on my garden zone.

Instead of planting a whole potato, the seed potato is cut into pieces. Each piece must have at least one bud or ‘eye’.  Depending upon the size and number of buds, I generally aim to cut each seed potato into 2-4 pieces. Plan to do the cutting at least 24 hours before you plant. This allows the cut side to dry/heal prior to planting.

If sprouts start to form, as in the pictures below, do not knock them off. Preserve these for planting. Some home growers will force these sprouts via a process called chitting. I have not done this because the seed potatoes I purchase always have sprouts.

Growing Requirements

Timing: Potatoes are a cool-season crop. In general, potatoes should be planted 2-3 weeks before your last frost date. Potatoes need 80-100 days to mature depending upon the variety. Here are some general guidelines based on your garden zone. Double check with your local Cooperative  Extension for exact timing.

• In colder gardening zones (6 and colder), plant potatoes in April and May.
• In gardening zone 7, plant January through March
• In gardening zones 8-10, plant in January and February. Fall potato crops can also be planted in these gardening zones. In zone 8 plant in August. In zone 9 plant in October and in zone 10 plant in November.

Light: Potatoes prefer full sun for at least 6 hours per day.

Soil: Potatoes need soil that is well-drained, moist, and fertile. The soil temperature should be at least 55°F during the day and 45°F at night. A pH between 5.0-6.0 is best (to determine your soil pH, perform a soil test by contacting your local Cooperative  Extension). Harvests will be better if you prepare your soil with the addition of composted organic matter and a balanced (N-Nitrogen, P-Phosphorus, K-Potassium) fertilizer of 10-10-10 (NPK). Work the organic matter and fertilizer into the top 6-8 inches of soil.

Spacing: Plant tuber pieces cut side down 3-6 inches deep and space each piece 9-12 inches apart. Leave 30 to 36 inches between rows.  Always double-check the guidelines on the specific seed potato you purchase for planting depth and spacing. Potato plants can grow up to 3 feet tall.

Caring for Potatoes

• Hilling: When potato plants are 8-12 inches tall, they should be hilled. Hilling is the process of mounding soil, compost, or straw up around the stem of the plant. Continue this process as the plant grows. Doing so ensures that the tubers growing underground stay covered and thus do not turn green. Green potatoes can be bitter tasting and green pieces should be cut off and discarded. Once the potato plant is fully grown, you will have mounted 6-8 inches along the stem of the plant.
• Fertilizing:  Potatoes require nitrogen, phosphorus, and potassium to grow well (NPK).  Fish emulsion with an NPK 2-3-1 is a good choice. Apply monthly up until one month prior to harvesting.
• Watering: Try to maintain consistent moisture in the soil. Potatoes need a consistent 1-inch of water per week to develop strong tubers. Sandy soil requires more frequent watering due to the fast-draining nature of this soil type.
• Mulch: Use organic mulches (e. g. straw, dry shredded leaves, wood chips) to ensure that the ground retains moisture and maintains soil temperature. Apply 2-3 inches around the base of the plant. This mulch can also be used for hilling as described above.
• Companions: Common companion crops include broccoli, cabbage, kale, and cilantro. Avoid planting onions with cucumbers, eggplant, or root vegetables.
• Crop rotation: Practice crop rotation to reduce disease. Plant in a bed where you have not grown tomatoes, peppers, or eggplant for the past three years. For more information on how to develop a crop rotation plan for your home garden, check out my post Crop Rotation for the home gardener.

Growing Potatoes in Containers

Growing potatoes in containers is also rather easy. Here are the steps to follow.

• For best results, potatoes need a container that is at least 2-3 feet tall and can hold 10 gallons of soil. Drainage holes in the bottom of the container are a must
• Place the container in a location that receives at least 6 hours of direct sunlight a day
• Start by adding 6-8 inches of a good lightweight potting soil that is amended with compost and fertilizer (see recommendations above)
• Plant tuber pieces cut side down at least 8 inches apart
• As the plant grows, continue to add more soil around the base of the plant. Leave 6 inches of foliage showing.
• Water when the first inch or two of soil dries out. Water until you see the water coming out of the drainage holes in the bottom of the container
• Fertilize monthly with fish emulsion. Stop one month prior to harvest.
• Potatoes can be harvested once the tops begin to yellow

Potential Problems Growing Potatoes

The best prevention is raising healthy plants and keeping them healthy:

• Plant potatoes when the soil is at least 45°F degrees at night
• Apply correct fertilizer
• Rotate crops each year. Because potatoes are in the nightshade family (tomatoes, eggplant, peppers), I rotate potatoes along with those crops. Do not plant potatoes in the same bed for 3 years
• Purchase disease-free seed potatoes
• Use drip irrigation or soaker hoses and keep the soil uniformly moist

Here are a few insect problems that can occur:

• Colorado potato beetle – regularly check under the leaves for small orange egg masses. Wipe off these egg masses or pinch off the leaf of the plant
• Cutworms will chew off potato stems at the soil line. Physically remove or place a piece of cardboard around the stem of the plant. Young seedlings are most susceptible.

If you suspect that something is wrong with your potatoes and live in the US, check with your Cooperative Extension for help in identifying and determining appropriate controls for pests and disease.

Harvesting Potatoes

Harvest potatoes at two different times depending upon your goal. For me, harvesting potatoes is so much fun. It’s like finding treasures as you continue to dig under the base of the plant.

• Harvest “new” potatoes 6-8 weeks after planting. With new potatoes, the skin is tender and can be rubbed off. New potatoes are not for storage and should be eaten shortly after harvest. You can even dig down and harvest a few of these potatoes and leave the rest in the ground until full maturity.
• Harvest mature tubers after the plant has flowered and the leaves are starting to turn yellow (80-100 days after planting the tubers).

As you harvest the potatoes be careful not to pierce the tubers. Set aside any tubers that have been pierced or cut during the harvesting process. Eat potatoes that have been pierced first.  

Before curing the potatoes, brush off the excess dirt but do not wash.

Curing and Storing Potatoes

Curing is a process that toughens up the potato’s skin and thus provides for longer storage life. Potatoes should be laid out on newspaper and cured for 10 days in a dark, well-ventilated, and humid area with a moderate temperature (60-65°F). After curing it’s best to move potatoes to a cooler location of about 40-45°F. This will ensure a longer storage life. Keep the storage area dark.  You might be asking yourself “where in my home should I store potatoes?”. Students from the University of Idaho performed a study and here are their home storage recommendations:

• Store in an extra refrigerator set a few degrees higher than normal (42°F)
• An unheated spare room, basement, attic, or garage is good for storage
• Store in a dark location or in a dark plastic bag that is perforated
• To elevate the humidity of stored potatoes, store them in a plastic bag with many perforated holes. Do not tightly seal the bag as airflow is important.

Different varieties of potatoes will have different shelf lives. Here are a few guidelines.

• Yellow and white potatoes store longer than red potatoes
• Thick skinned potatoes store longer than thin-skinned potatoes (new potatoes)
• Late maturing potatoes store longer than early maturing varieties

I hope this post has given you the information on how to successfully grow great potatoes. It really is a fun and easy vegetable to grow!

Additional Information

You may find these posts to be of interest.

• Creating and maintaining an organic vegetable garden – Part One
• Creating and maintaining an organic vegetable garden – Part Two
• How to use floating row cover in your organic garden
• Managing garden pests with an integrated approach
• Companion planting for pest management in the vegetable garden
• Getting started with seeds, 4 secrets for successful seed starting
• Five pieces of planning advice for the vegetable gardener

Botanical Information

• Family: Solanaceae
• Genus:   Solanum
• Species: S. tuberosum

References

• University of Minnesota Extension
• Michigan State University
• University of Florida IFAS Extension