How to grow Potato?

Potatoes are the most important vegetable crop in the world. They provide more usable protein per acre than any other crop (up to forty times more per acre than cows). They may yield from 10,000 to 30,000 pounds per acre. Potatoes are unique as the only garden crop you could live on (at least for a while). At one time, Irish peasants really did live on a diet of potatoes and milk and their population increased rapidly (until the Potato Famine).

Many gardeners don't grow potatoes because they believe they need a lot of space, are cheap to buy, and don't taste much better than store bought. However, they are actually one of the most space efficient crops you can grow, considering the amount of nutrition they provide. A 10 square-foot planting can yield 20 to 40 pounds of tubers. Home grown potatoes also taste better than those you buy and are one of the great treats of the summer garden.

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Potato History

Potatoes originated in the mountains of Central and South America and have been cultivated for over 6000 years. There are still a huge number of varieties grown in that region. The potato wasn't a success when it was first brought to Europe, probably because they were short varieties and it didn't start to produce until late in the year. However, it was eventually accepted, presumably as better varieties were developed.

Soil Preference

PH (min/max): 4.8 - 7.0
PH Ideal (min/max): 5.4 - 5.5

Potatoes will grow in most soils, even those that are too [acidic] for most crops. For best results, they prefer light, deep, well-drained sandy soils. They prefer a more acidic soil than most vegetables, as it increases yield and decreases the incidence of [Scab] (a disease that mostly occurs in soils with a pH above 6.0). They don't like heavy wet clay, or very [alkaline] soil.

Potatoes aren't a fussy crop, but they respond well to any soil improvement. If the soil is heavy or compacted, deep cultivation such as double digging is very beneficial as it enables you to loosen the soil and add organic matter (use [compost], aged manure or leaf mold). If the soil is too alkaline then add sulfur, pine needles or another acidifying agent. Don't lime the soil when planting potatoes.

For more information on soil pH [click here.:Soil pH#The Effects of High pH]

How to care for Potato?

Potatoes are a beneficial crop for the garden, as their growth and harvest improves the [tilth] of the soil and suppresses weeds.

It is important to keep the soil evenly moist (but not wet) for best growth, as lack of water results in smaller tubers. It is also important to water uniformly, making sure it penetrates through the dense foliage and down to the full root depth (or at least the top 12 inches where the greatest proportion of roots are found).

Potatoes can grow in most soils, but will be more productive in a sandy loamy soil that is moisture retentive and fertile. Although [nitrogen] is important, too much can cause abundant top growth (leaves) and fewer tubers. Potatoes need a good supply of [phosphorous], from bone meal or colloidal phosphate. The most important primary [nutrient] for potatoes is [potassium], which will increase yield, improve quality and hasten maturation. It is especially important during the time when the tubers are forming.

High quality, aerobic [compost], low in wood or rice byproducts, is preferable to manure as a [fertilizer]. If you must fertilize with manure, be sure it is well-aged and that it is incorporated shallowly into the soil at least 3 to 4 weeks before planting, otherwise the process of soil digestion will deprive the germinating potatoes of vital nutrients and water. Do not fertilize with fresh manure, as this can cause [scab]. One of the best ways to prepare the ground for potatoes is to [cover crop]. Cover crops or [green manure] greatly improve the soil's [tilth], [organic matter], microbial activity, and water holding capacity, and significantly increases nutrient availability for the next crop.

Using wood ashes with potatoes is somewhat controversial because it can raise the pH (potatoes have less problem with scab disease when growing in acid soil). At the same time it can raise yields significantly, as this study shows.

Seed Viability:

When we talk about seed-saving with potatoes we are usually talking about tubers, not seed. Saving your own tubers and re-planting them is frowned upon for the same reason as using supermarket tubers; it can lead to virus diseases. If you want to save your own seed potatoes, just store them very carefully and don't eat them.

You may want to experiment with actual potato seed as well. Many varieties don't usually produce seed, but some do. It can be gathered from any ripe fruits your plants produce. These take about two months to ripen and may be green or purple. Squeeze out the seeds into a bowl and wash them. The good seeds sink and bad ones float.

Sun: min. 6 hours daily

Full sun.

Conditions:Cool, Warm

Season:Long Season

Clamp: Large quantities of Potatoes can be stored over the winter in a clamp. This works best in light, well drained soil and should be in a sheltered position. This can be tricky if you have never done it before, as lots of things can go wrong.

Start by digging out the soil in the area of the clamp to a depth of 10˝ and then lay down a 3˝ to 6˝ layer of straw or dry leaves (you might first lay down a layer of Gopher wire to foil rodents). A piece of perforated pipe is arranged in the center and the roots are placed around it to form a cone or prism shaped pile (a vent can also be constructed from straw). The pile is then covered with a 6˝ layer of straw, or leaves (more in very cold climates). Finally the straw is covered with a 6˝ layer of soil, which is packed down with a spade. Some of this soil comes from the original excavation; the rest is obtained by digging a drainage trench around the clamp. Keep the vent open on top of the clamp, unless it gets very cold, in which case it should be closed up with straw.

Storage Req: Cool, Ground
Storage Temp: 40-50°F
Storage Length: 1-90 days

Careful storage is very important. If potatoes are not given ideal conditions they will soon become inedible due to rotting, turning green or sprouting. Temperature is the most critical storage factor.

If conditions are too warm (above 50˚ F) they will sprout as soon as their natural dormancy period is over in 2 or 3 months (of course this won’t matter if you only have a 2 month supply of tubers to store).

If it is too cold (below 40˚ F) their starch may turn to sugar and give them an off flavor.

Prepare the tubers by air-drying in a dark place for several days (don’t wash) and then cure them at 60˚ F for 2 weeks.

They should then be stored at 40 to 50˚ F with high humidity. Keep them in wooden boxes, or sacks, with good air circulation (never in plastic bags) and check periodically for rot. Keep them in the dark or they will turn green. If stored properly they can last up to 6 months.

Storage Req: Cool
Storage Temp: 60-70°F
Storage Length: 1-21 days

If it is too cold (below 40˚ F) their starch may turn to sugar and give them an off flavor.

Prepare the tubers by air-drying in a dark place for several days (don’t wash) and then cure them at 60˚ F for 2 weeks.

Storage Req: Cool, Moist
Storage Temp: 40-50°F
Storage Length: 90-180 days

Problems

Colorado Potato Beetle

On a small scale you can simply hand pick off any beetles you find and scrape off the tiny orange egg masses from under the leaves (and any newly hatched larvae). The larvae are eaten by many predators, though the adults are fairly poisonous.

Verticillium wilt

This fungus shows itself by the tops dying off prematurely (it’s also known as Early dying fungus). You may still get a small crop of potatoes from affected plants, but they won’t store well. This disease can last for years in the soil. To eliminate it, don't plant potatoes in the same spot for at least 4 years. Other members of the Solanum family are also affected, so they shouldn’t be grown either during that period (except for a few resistant varieties).

Late blight

(Phytopthora infestans) This is the disease that caused the famine that depopulated Ireland, by killing one and a half million people and causing another million to emigrate. It is called Late Blight because it likes warmer weather and usually occurs after Tomatoes (which it also affects) have flowered. It doesn’t much bother early crops. This fungus first manifests itself as spots on the lower leaves in cool weather, but then the leaves die and brown patches appear on the tubers. The only thing you can do is dig the tubers 2 weeks after the tops die down and use them (then spores from tops won’t be transferred to the tubers). This disease affects yield, but doesn’t affect storability (of course you wouldn’t use infected potatoes for seed). Many modern varieties have some resistance to Late Blight.

Pests

The Potato has more than its fair share of disease and insect pests. Fortunately these aren’t found everywhere; in some favored areas Potatoes have few problems and are very easy to grow. The severity of potato pests varies from year to year, with different growing conditions. In some years they do little harm, in other years they can be devastating. Warm humid conditions are the worst for Potatoes.

Scab

(Streptomyces scabies) Soil bacteria cause this very common disease. It is undetectable above ground and the damage is mainly cosmetic, so it is not very serious unless you are growing for market (it reduces their marketability). Alkaline soil (above 6.0 pH) and lack of moisture are the main causes of scab. It persists in the ground for several years and can also infect other root crops such as carrot, beet and turnip. The best ways to prevent scab is to rotate annually, keep the soil somewhat acid (don’t lime it) and to use resistant varieties. Abundant water may reduce damage from Scab.

Viruses

These aren’t always an obvious problem, but they can reduce yields considerably. You may avoid them by using certified seed and not saving your own tubers for planting.

Removing viruses: It is possible to get a virus-free plant from an infected tuber (this is only worthwhile if you have a special variety). You plant the tuber in a container of sterile potting mix and keep it in a warm place to grow. When the shoot reaches 6˝ to 8˝ high you cut it off 2˝ to 3˝ above the soil line (it should never touch the soil or the rest of the tuber). The shoot can then be rooted in another container of sterile potting mix and it will hopefully be virus-free. Just hope that when you plant it out your garden is also free of viruses.

Potato Types

Mix Potatoes are a mix of different colors and sizes.

Yellow & All Purpose

Yellow Potatoes are very versatile and are good mashed, steamed, baked, boiled or roasted.

Their yellow color is due to vitamin A and anthoxanthins, which have beneficial antioxidant properties.

Fingerlings

Fingerling Potatoes are small, finger shaped potatoes which grow small and narrow. They vary in skin color from yellow to orange to purple. They are primarily known for their roasting qualities.

White

A quality white potato is firm with smooth skin and a bright-white to cream color.

Red Potatoes are very versatile and are good steamed, baked, boiled or roasted. They are typically small with thin smooth skin and have red coloring. They are high in moisture and sugar, but low in starch content.

Blue & Purple

This variety of potatoes has a purple skin and flesh which turn blue when cooked. Blue and Purple potatoes have all the same characteristics as more well-known potatoes types.

Russet

Russet Potatoes are large, brown-skinned, white-fleshed potatoes. They are know for their baking and frying qualities. Russet Potatoes were developed by Luther Burbank in the 1870s.

Pests

Aphids
Blister Beetle
Colorado Potato Beetle
Gophers
Leafhoppers
Armyworms
Cutworms
European Corn Borer
Flea Beetle
Nematodes
Whiteflies
Wireworm
Symphylans

Diseases

Tomato Spotted Wilt Virus (TSWV)
Southern Blight
Bacterial Wilt
Curly Top
Rust
Scab
Tobacco Mosaic Virus
Fusarium Wilt
Blackleg, Aerial Stem Rot
Cercospora Leaf Spot
Late Blight
Powdery Mildew
Verticillium Wilt

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