Potato (Solanum tuberosum)

Growing a hearty crop of potatoes in your backyard garden is easier than ever. With just a little bit of effort, some hilled soil, and high-quality seed potatoes, you can have mounds of potatoes ready for harvest in just a few short months.  This simple, step-by-step guide will show you everything you need to know about adequately planting, caring for, hill, and harvesting platefuls of delicious, homegrown potatoes.

I. Appearance and Characteristics 

The potato is a starchy root vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are tubers of the plant Solanum tuberosum, a perennial in the nightshade family Solanaceae.

Potato plants are herbaceous perennials that grow about 60 centimetres (24 inches) high, depending on variety, with the leaves dying back after flowering, fruiting and tuber formation. The alternately arranged leaves have a petiole with six to eight symetrical leaflets and one top, unpaired leaflet, which is 10 cm (3.9 in) to 30 cm (12 in) long and 5 cm (2.0 in) to 15 cm (5.9 in) wide. They present hairs or trichomes on their surface, to varying degrees depending on the cultivar.

Potato plants bear white, pink, red, blue, or purple flowers with yellow stamens. Potatoes are mostly cross-pollinated by insects such as bumblebees, which carry pollen from other potato plants, though a substantial amount of self-fertilization occurs as well.

The plant develops tubers as a nutrient storage organ. Traditionally, it was thought that the tubers are roots because they are developed underground. In fact, they are stems that form from thickened rhizomes) at the tips of stolons. These stolons arise as branches from underground nodes. On the surface of the tubers there are “eyes,” which act as sinks to protect the vegetative buds from which the stems originate. The “eyes” are arranged in helical form. In addition, the tubers have small holes that allow breathing, called lenticels. The lenticels are circular and their number varies depending of the size of the tuber and environmental conditions. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.

After flowering, potato plants produce small green fruits that resemble green cherry tomatoes, each containing about 300 very small seeds. Like all parts of the plant except the tubers, the fruit contain the toxic alkaloid solanine and are therefore unsuitable for consumption. All new potato varieties are grown from seeds, also called “true potato seed”, “TPS” or “botanical seed” to distinguish it from seed tubers. New varieties grown from seed can be propagated vegetatively by planting tubers, pieces of tubers cut to include at least one or two eyes, or cuttings, a practice used in greenhouses for the production of healthy seed tubers. Plants propagated from tubers are clones of the parent, whereas those propagated from seed produce a range of different varieties.

Raw potatoes contain toxic compounds known as glycoalkaloids, of which the most prevalent are solanine and chaconine. Solanine is found in other plants in the same family, Solanaceae, which includes such plants as deadly nightshade (Atropa belladonna), henbane (Hyoscyamus niger) and tobacco (Nicotiana spp.), as well as the food plants eggplant and tomato. These compounds, which protect the potato plant from its predators, are generally concentrated in its leaves, flowers, sprouts, and fruits (in contrast to the tubers).

II. How to Grow and Care

Sunlight

Potatoes need 6-8 hours of daily sunlight for optimal growth, crucial for robust development and higher yields. Insufficient sunlight leads to stunted growth, reduced yields, and increased risks of diseases. Choose planting spots with uninterrupted sun exposure, rotating crops to sunny areas yearly. Use grow lights in low sunlight regions.

In temperate climates, a south-facing site is ideal, avoiding shade from structures or other plants for optimal sunlight intake.

Temperature and Humidity

Potatoes thrive in cool climates, best suited for zones 3-10, with an ideal soil temperature for planting at around 60°F/16°C. Once sprouting, consistent soil temperatures of 65-75°F/18-24°C promote optimal tuber swelling. Night temperatures of 55-65°F/13-18°C encourage strong underground development, while sustained temperatures above 80°F/27°C can stunt growth.

Light frost is tolerated, but prolonged freezing causes damage. Humidity levels of 55-75% are ideal; lower humidity requires increased irrigation and mulching to prevent soil drying. Monitoring both temperature and humidity helps adapt to less-than-ideal conditions for potato growth.

Watering

Potato plants rely on a steady water supply. Make sure the plants receive at least one inch of water per week. They are sensitive to drought conditions, especially when they flower, as that is the peak time for forming the potato tubers. Mulching around the plants can help retain moisture.

Soil

Grow your potatoes in soil with an acidic pH between 5.0 and 6.0. Potatoes grown in soils with a higher pH seem prone to scab, which produces rough spots on the potato. Potatoes don’t like particularly rich soil. If you have a good amount of organic matter in the soil and the pH is neutral to acidic, the potatoes should be happy. The soil needs to be loose and well-draining. If you have soil that is heavy in clay, you will need to prepare it with loose soil down to the depth where the potato tubers will grow.

Fertilizing

Enhancing potato nutrition begins with pre-planting soil amendment using compost or manure for sustained feeding.

Midseason, supplement with organic options like worm castings, fish emulsion, seaweed, bone/blood meals, or wood ash in moderation to boost growth, provide micronutrients, enhance yields, deliver targeted nutrition, and accelerate maturity.

Interplanting leguminous cover crops fixes nitrogen and improves soil health. When using organic fertilizers, test soil, rotate fertility areas, and mix granular products beforehand, reserving liquid feeds for established plants.

Opting for organic nutrition reduces reliance on synthetic chemicals.

Planting Instructions

Cold-climate gardeners usually plant potatoes in mid to late spring. In a warm climate, you will do best planting in either late summer or late winter, so the plants aren’t trying to grow during the hottest months.

Plant seed potato pieces with the cut-side down (eyes should face up) in a hole or trench that’s 6 inches deep. Leave 12 inches of space around each on all sides. Sprinkle 2 tablespoons of a low-nitrogen, high-phosphorus fertilizer between each segment. Then cover the potatoes and fertilizer with 2 inches of soil and water well.

It’s fairly easy to grow potatoes successfully if you follow some basic guidelines:

• To extend your potato growing season, choose an early variety as well as a late-season variety. You plant these at the same time, but the late-season variety is harvested several weeks after you’ve already dug the main season potatoes.
• Buy certified disease-free seed potatoes. Attempting to plant potatoes purchased from the grocery store is a gamble. Besides the disease problem, potatoes are often treated with a growth inhibitor to keep them from sprouting in the grocery store.
• Don’t plant potatoes where tomatoes or eggplant were grown the year before. These vegetables are in the same nightshade family as potatoes and can attract similar pests and problems.

Planting potatoes can be done in one of two ways: a trench-and-hill method that involves adding soil around the stem as it grows upward, and a simple scatter method.

• Trench method: A traditional potato planting method involves digging a shallow trench about 6 inches deep and placing the seed potatoes in the trench, eyes facing up. Then cover the potatoes with a couple of inches of soil. As the potato plant grows, the soil is continually hilled up along the sides of the plants. This keeps the soil around the developing tubers loose, and it keeps the surface tubers from being exposed to sunlight, which will turn them green and somewhat toxic. Add soil to the hill whenever the plants reach about four to six inches in height. You can stop hilling up soil when the plants begin to flower.
• Scatter method: Some gardeners prefer to simply lay the seed potatoes right on the soil and then cover them with a few inches of mulch. You can continue layering mulch as the plants grow. If you have a rodent problem, this method is probably not your best choice.

Pruning

Propagation

Seed potatoes aren’t really seeds at all. They are full-size potatoes bred for the purpose of growing more potatoes. They start producing shoots from the potato eyes. You’ve probably seen this happen when you’ve stored potatoes in the kitchen for too long.

Seed potatoes can be planted whole or cut into pieces, with each piece containing an eye or two (or three). Because potatoes can rot if the soil is too cool or wet, many gardeners prefer to allow the cut pieces to callus over by leaving them exposed overnight. You can also purchase a powdered fungicide for dusting onto the pieces, to avoid rotting.

Mulching

Mulching offers a myriad of benefits crucial for optimal tuber growth. It retains soil moisture, ensuring a consistent environment for tubers to flourish. The stabilizing effect on soil temperatures is another advantage, promoting an ideal climate for potato development.

The practice diminishes weed growth, preventing competition for vital nutrients. Notably, mulching protects against the greening of tubers near the soil surface.

Regarding materials, options like straws, aged leaves, or perforated black plastic are recommended, each with unique advantages.

After planting seed potatoes and before sprouts emerge, apply 4-6 inches of loose mulch, keeping it away from stems. It’s essential to replenish organic mulch midseason, ensuring a continuous protective layer. Leave ample space between plants for soil hilling, and remember that potatoes thrive when shielded from direct light exposure.

Pests and Diseases

Potatoes are prone to problems, so be observant for these:

• Beetles and aphids can defoliate the plants. Monitor for them early in the season, before they become a major problem. Check the undersides of leaves for the eggs and larvae of common beetle pests like the Colorado potato beetle. You can usually remove these by hand.
• Thin, red wireworms attack underground. Rotating the location where you plant your potatoes each year will help avoid wireworms.
• Scab is a common potato disease that looks like raised, corky areas on the skin or sunken holes on the surface. Lowering the soil pH will help control scab. Add peat moss to the planting area.
• Late blight (the cause of the Irish potato famine) turns the foliage black, then moldy. Burn or dispose of the foliage. Do not compost it. The potatoes can still be harvested, but you should wait several weeks. To avoid this problem, use certified disease-resistant seed potatoes.

Growing in Containers

Growing regular or sweet potatoes is accessible in large, deep containers with drainage holes using a lightweight, nutrient-rich potting mix. Choose compact, early potato varieties suited to pots and allow 8 inches between seed tubers planted 4-6 inches deep with sprouts up. Place containers in full sun and keep a mounding mix as stems sprout, leaving just foliage exposed.

Avoid disturbing roots once flowering starts. Check moisture every few days, watering thoroughly. Harvest as soon as tubers plateau in size. Yields will be smaller than in-ground. Mix and refresh soil between plantings.

III. Uses and Benefits 

• Ornamental uses

Culinary uses

Potatoes are prepared in many ways: skin-on or peeled, whole or cut up, with seasonings or without. The only requirement involves cooking to swell the starch granules. Most potato dishes are served hot but some are first cooked, then served cold, notably potato salad and potato chips (crisps). Common dishes are: mashed potatoes, which are first boiled (usually peeled), and then mashed with milk or yogurt and butter; whole baked potatoes; boiled or steamed potatoes; French-fried potatoes or chips; cut into cubes and roasted; scalloped, diced, or sliced and fried (home fries); grated into small thin strips and fried (hash browns); grated and formed into dumplings, Rösti or potato pancakes. Potatoes can also be cooked in a microwave oven to produce a meal very similar to a steamed potato, while retaining the appearance of a conventionally baked potato. Potato chunks also commonly appear as a stew ingredient. Potatoes are boiled between 10 and 25 minutes, depending on size and type, to become soft.

Other uses

Potatoes are also used for purposes other than eating by humans, for example:

• Potatoes are used to brew alcoholic beverages such as vodka, poitín, or akvavit.
• They are also used as fodder for livestock. Livestock-grade potatoes, considered too small or blemished to sell or market for human use but suitable for fodder use, have been called chats in some dialects. They may be stored in bins until use; they are sometimes ensiled. Some farmers prefer to steam them rather than feed them raw and are equipped to do so efficiently.
• Potato starch is used in the food industry as a thickener and binder for soups and sauces, in the textile industry as an adhesive, and for the manufacturing of papers and boards.
• Potatoes are commonly used in plant research. The consistent parenchyma tissue, the clonal nature of the plant and the low metabolic activity make it an ideal model tissue for experiments on wound-response studies and electron transport.
• Potatoes have been delivered with personalized messages as a novelty. Potato delivery services include Potato Parcel and Mail A Spud.

IV. Harvesting and Storage

New potatoes are small, immature potatoes. You can harvest a few of these without harm to the plant once the plant reaches about one foot in height—about 50 days after planting. When the plant is in flower, the new potatoes are generally ready to harvest. Gently feel around in the soil near the plant and lift them out.

Expect to wait two to four months (up to 120 days) for potatoes to reach their full size. The entire crop is ready to harvest once the tops of the plants die off. You can leave the potatoes in the ground for a few weeks longer, if the soil is not wet.

Harvest carefully by hand or with a shovel or shovel. Turn the soil over and search through for the round or oval treasures. The tubers can branch out, and digging in with a fork is a sure-fire way of piercing a potato or two. Damaged potatoes are still edible, but they won’t keep for long.