A good potato crop starts with good seed potatoes. A garden store will have certified seed potatoes that are free of disease. Don't rely on old potatoes from your root cellar because they could be carrying disease organisms without showing it.
Preparing the Soil
The ideal soil for growing potatoes is a silt or sandy loam,well drained and high in organic materials. If necessary, work in some leaf mold or composted manures to boost the organic content. Never use fresh manure. Poorly drained soil will cause the seed potatoes to rot before they sprout.
Soil pH should be no higher than 6.5, with a higher pH often resulting in potato scab. It's best to avoid the use of lime, which raises the pH.
Plant small seed potatoes whole, and cut the bigger ones into two or three blocky pieces. Be sure to leave two or three buds (or eyes) on each piece. Cut them a day or two before planting and leave them in a warm place to heal and dry out a little. Douse the potatoes with sulfur immediately after cutting the up. This acts as a natural protectant against rot. Two ounces will treat about 10 pounds of seed potatoes. The sulfur will also lower the pH of the soil around the potatoes a bit.
Plant your earliest potatoes five to six weeks before the last expected frost. Red Norland is a good early producer. A frost before the shoots come up is no problem, but if your potatoes have sprouted, protect them in case of frost. Plant the main crop of potatoes just after the last frost date.
Plant Irish potatoes under straw, ha;y, leaves, or mulch. This method, which is sometimes called "lazy-bed" eliminates the need for cultivation after sowing, permits a significant increase in space utilization, and allows harvesting on an as-needed basis.
Set up a rectangle that is narrow enough that you can reach the center from either side without stepping in the bed. Cultivate the soil deeply and if heavy rains are a problem in your area, give the bed a slight slope to permit drainage. Place the potato chunks, cut side down, 12 inches from the sides and ends and 12 inches apart in all directions.
After the chunks are in place and pressed down firmly in the soil (no need to bury them) spread a layer of straw, hay or shredded leaves on top of them. You will need a six-inch layer of bailed hay or 12 to 18 inches of loose hay. In windy areas, weigh down the hay with wire, wood slats or a sprinkling of soil. After a rain or two, you will probably not need the weight.
Hoe or dig a trench about 12 inches wide and 6 inches deep. If you are not sure your soil is rich enough, put a 2-inch layer of compost in the trench and work it into the soil. Plant potato chunks, cut side down, 12 inches apart and 1 inches deep. As plants emerge, hoe the soil up to them gradually filling the trench and building a row-long hill about 8 inches high. Rows should be 18 inches apart. Be sure that water will not stand between the rows during heavy rain
Harvesting and Storage
Pick a relatively dry period for your harvest. Wait until the vines are dead and dry. This is a sign that your potatoes have fully matured. Work carefully to avoid damaging your crop. You may have to dig down several inches to find all the potatoes. If you have used the lazy-bed method, simply remove the straw and pick up your potatoes.
Let the potatoes dry for one or two hours then move them into storage. If the potatoes are to be used in the next four to six weeks, they can be stored in a dark area with temperatures as high as 70 degrees. For winter storage, fully mature potatoes should be stored in the dark at temperatures between 30 and 40 degrees with a high humidity and good air circulation. They will keep this way for 5 or 6 months. Darkness is essential, as light will promote greening. Higher temperatures may cause them to sprout.
- Colorado Potato beetle
- This beetle is resistant to many controls, including insecticides. Adults are about 1/3 inch long with a hard, round outer shell. The wing covers alternate creamy yellow with ten black stripes. The larvae are up to 1/2 inch long, fat and reddish with two rows of black dots along either side. Their range is most of North America with the exception of the South and Pacific Northwest. They can strip plants of foliage and do the most damage in small plots. Crop rotation is a good defense. Interplant with repellent plants such as snap beans, marigold, garlic, onions, flax, catnip, coriander, nasturtiums, tansy, dead nettle and horseradish. Because they are not good climbers, grubs can be halted by thick mulch. Bt is effective against larvae when applied early. Predators include toads, paperwasps and ground beetles. Try sprinkling the plants with water, then with wheat bran. The beetles will eat the wheat bran, which then swells causing the beetle to explode. Effective homemade sprays can be made from boiled basil or cedar chips. Add 2 tbsp. Epsom salts per gallon of liquid.
- Flea Beetles
- Flea beetles are found throughout North America. Most are under 1/10 inch long. Colors range from high gloss black to iridescent blue, green, or bronze. Some have yellowish legs, antennae, or wing markings. You will never get close enough to get a good look at the little critter. The bugs winter over in garden debris, so keep the garden clean in winter. To get rid of them, place trap (a shallow dish full of beer works well) near infested plants. Teas made from repellent plants such as wormwood, mint, hot peppers, garlic, onions or catnip make effective sprays. A sprinkling of wood ashes or ground limestone discourages the beetles, who dislike dustiness.
- Early and Late Blight
- Humidity seems to promote blight, so it will be seen more often in hot, humid climates. The best defense against this and all other fungal diseases that attack potatoes is to buy certified seed stock so that you start out free of disease. Since the fungus can live in the soil, crop rotation in another preventative. Wait until the tops are dead and dry before harvesting, then rake and burn all plant residue.