Varieties

Many varieties of potatoes are certified in the United States each year. Some are more specific in their adaptability to certain regions than others. Furthermore, these varieties have a wide range of maturity from very early to late.

For the small garden, choose potato varieties that are early in maturity. This facilitates intercropping with some of the later vegetables that require more room further into the season after the potatoes have been harvested. For the larger garden the mid-season and late varieties can be grown.

Potato varieties adapted to the home garden are:

Norland: A very early red variety with oblong, smooth tubers with shallow eyes. It has moderate resistance to common scab and good table quality. It is widely adapted and commonly available in the United States.

Irish Cobbler: An early maturity white variety with round to blocky tubers and deep eyes. It is a good producer and has excellent table quality. It is very susceptible to common scab.

Norgold: An early maturing russet variety with very smooth long to oblong tubers and shallow eyes. It is scab-resistant. Cooking quality is good, but under stressed growing conditions tubers could develop hollow heart.

Anoka: A newer early white variety with round to oval smooth uniform tubers. It is an all purpose potato well adapted to the home garden at 14-inch spacing. It has less tendency to darkening after cooking.

Superior. A midseason white variety with a rather tough skin. It is moderately resistant to scab and has high table quality.

Kennebec: A very popular late variety with white skin and shallow eyes. It has resistance to late blight disease. Cooking quality is excellent. Because of the thin skin the tubers are very susceptible to sunburn and greening.

Red Pontiac: A high yielding red variety with a midseason maturity. Tubers are oblong with medium deep eyes. With excessive moisture the tubers tend to become oversized. Cooking quality is only fair, but it is a good variety for winter storage.

Red LaSoda: A good red variety for gardens in the South. It is midseason in maturity with round to oblong tubers. Eyes are medium deep. It appears to have some tolerance to higher temperatures.

Katandin: A very popular white variety with wide adaptability. Tubers are round to oblong with shallow eyes. It is midseason to late in maturity. Cooking quality is good.

Sebago: A late maturing white variety with resistance to late blight. It is popular in the South as well as in the East as a home garden variety. Tubers are smooth and nearly round with shallow eyes. Cooking quality is fair to good, but not as mealy as Kennebec.

Russet Burbank: Also known as Netted Gem and Idaho Russet. It is a late variety with long cylindrical to slightly flattened tubers with a heavily netted skin. Under conditions of moisture stress the tubers often develop growth cracks or knobs. It has some scab resistance. Table quality is excellent, especially for baking. Better size is obtained with a 14- to 16-inch spacing.

Consult the local extension service for new potato introductions with specific adaptation to your area. Potato breeders continue to develop varieties with improved market and culinary quality combined with high yield and multiple disease resistance.

Soil Needs

Like most vegetable crops, the potato is adapted to a wide variety of soils. It performs best, however, on a sandy loam well supplied with organic matter and plant food. High organic soils like peat or muck can be used if they are well drained. Heavy fine-textured soils are satisfactory if their structure is improved with organic matter.

Applying organic matter in the form of well-rotted manure, compost or similar materials will improve the structure for better air-holding capacity as well as water-holding capacity. Apply it to the top of the soil in early spring at the rate of 3 to 4 bushels per 100 square feet of area. With a rotary tiller, or spading fork, incorporate it thoroughly into the soil to make a uniform tilth or structure. This practice binds together coarse-textured sandy soils and breaks up fine-textured, heavy clay soils.

The best soil-acidity range for potatoes is between pH 4.8 to 5.4. On soils with a pH of 5.5 to 7.0 the potatoes usually are scabby. Lime should not be used unless a soil test indicates a pH below 4.8.

One of the most widely used commercial fertilizers for the home garden is 5-10-5. Another is 10-10-10. These analyses should provide sufficient plant food for a good potato crop. Either fertilizer can be spread at the rate of 15 pounds per 1,000 square feet at planting time.

Some gardeners prefer to place the fertilizer in bands below and slightly to the side of seed pieces. If the rows are 3 feet apart and 100 feet long, apply 6 to 8 pounds per row. A side dressing may be applied after the plants are 4 to 6 inches high. Use the same rate in an open trench 4 inches deep and 6 inches away from the plants.

Local agricultural extension offices will have more specific recommendations for your area; however, the suggestions given here should generally be adequate.

Manure is often used as a source of nutrients where scab is not a problem. This disease is more serious when fresh manure is used. Manure that is well-rotted or applied during fall or early winter is less apt to increase potato scab.

Rotate the location of potatoes in your garden each year. At least a 3-year rotation is suggested for all garden crops. In large gardens where space is not limited it helps to plant a small grain such as rye as a nurse crop seeded down to red clover the second year. After the hay is cut the third year, the plot can be plowed down and fallowed. Potatoes are then planted in the area the fourth year. Such a rotation will help control diseases, insects and weeds. Potato yield and quality will be improved.

Planting

The potato is considered a cool-season crop and can be planted as soon as frost is out of the ground and the soil dry enough to work. If soil temperature is below 40 F (5 C), however, there is a greater chance for seed piece decay, especially when cut seed is planted. Using whole seed or cut seed that has been suberized will help prevent the problem. This is a process of healing over the cut surface by holding the cut seed for a period of 7 to 10 days at a temperature of 60 to 70 F (16 to 21 C) and a relative humidity of 85 percent with good air circulation.

Planting dates will vary with the locality and soil type. In the North, potatoes usually are planted from April 15 to May 15, and in the South from November to February.

Plant early to get the highest yield. By planting early maturing varieties as soon as the soil is dry enough to prepare and warm enough to prevent seed decay, you can have potatoes of usable size by midsummer. These will not keep as long as potatoes that matured later in the growing season, however.

Proper size of the seed piece planted is important. Experience has shown that 1 1/2- to 2-ounce seed pieces are best. This is about the size of an average hen's egg. The so-called "potato eyes" are generally too small to provide sufficient nourishment, and as a result weak plants develop. Potatoes can be planted either whole or cut. If cut, there should be at least one eye on each piece and the pieces should be uniform and blocky.

Plant the seed immediately after cutting, otherwise viability will be lowered by loss of moisture and entrance of rot organisms.

Some gardeners prefer to treat seed Potatoes before planting. A good fungicide dust such as captan will help protect the cut seed pieces after planting and assure better emergence.

Seed can be cut and stored for 10 days or more if it is properly suberized.

If available, whole B-size seed is best. The value of planting small Potatoes without cutting them has been known in Europe for many Years. With the skin around the entire potato, it is protected from soil organisms and the result is less seed decay and better stands of plants.

If whole or B-size seed is used, it should be from certified stock. Virus-infected plants tend to produce smaller tubers, and when such seed is planted whole, weak and poor yielding plants result. However, small tubers from certified seed will produce as good a crop as large potatoes cut for seed.

Plant potatoes deep enough so the new tubers will develop sufficiently beneath the surface to avoid sun-burning. Generally the seed should be planted in contact with moist soil, 3 to 4 inches deep. This depth will vary with the soil's temperature and moisture. A shallow covering of about 2 to 3 inches of soil over the seed will result in quicker emergence and less sprout damage from rhizoctonia and blackleg disease.

In the small garden a trench is usually opened with a hand hoe or cultivator. Distance between rows will depend on the type of cultivation to be used. A 36-inch row is quite common, but rows can be spaced 24 inches apart if cultivated by hand. Within the trench, place the seed pieces 12 to 18 inches apart, depending on variety. Oversize potatoes in varieties like Kennebec can be prevented by planting seed pieces as close as 6 to 8 inches. This also helps reduce the amount of hollow heart in tubers.

The amount of seed needed varies with the spacing and size of the seed piece. When cut to a 1 1/2-ounce size and planted 12 inches apart in the trench, a 100-foot row would require about 9 pounds of seed potatoes.

Water when dry periods occur, but only if the soil needs it. Once watering is begun it should be continued until the soil is moistened to an 8- to 12-inch depth. Water thoroughly at weekly intervals when needed. Dry periods alternating with wet periods can cause potatoes to develop such abnormalities as hollow heart, growth cracks, and knobs.