Growing potatoes in your garden

Idaho is known across the country and even the world for its Idaho potatoes. Potatoes are a popular crop to grow in your garden and, with the right information, can be easy to grow as well. Potatoes vary in shape, size, skin color and flesh color. Some common types of potatoes are russets, reds and whites. With over 5,000 varieties, potatoes are the fourth most common crop grown in the world.

The most important thing you should do when growing potatoes is buy certified seed each year. Potatoes are susceptible to a variety of diseases. Certified seed has been inspected and is within acceptable limits for disease. Local nurseries and garden centers are the best place to find the seed you are looking for.

Prior to planting, it is best to keep seed out of direct sunlight and between 50 and 65°F for two weeks to encourage germination and growth. Potato tubers are called seed pieces when they are planted in the soil. Each seed piece should have at least two eyes, as the stem will emerge from the eyes and grow into mature plants. Small seed pieces between one and two inches in diameter can be planted directly in the soil, but for larger potatoes you will need to cut them into smaller two-to-three-ounce pieces. Potatoes smaller than one inch should not be used as seed. If you need to cut the potatoes into smaller pieces, use a sharp knife and make clean cuts. In between each cut disinfect the knife with rubbing alcohol to prevent spreading disease.

Cut seeds can be planted immediately if the soil temperature is above 55°F. If you are waiting to plant after you cut the seeds, put them in a dark, humid room to encourage a callus to form, protecting the cut site from diseases in the soil. Cool, wet soil can delay sprouting emergence or cause seed pieces to rot. Seed should be planted four inches deep with the eyes pointing up, one foot apart.

Rows should be three feet apart. After the potatoes emerge, hill them up by putting two inches of dirt over the top of them to prevent green potatoes.

The garden site where you plant the potato seed should be well-drained and have no low spots where water can pool. Potatoes grow best in sandy loam soils with a pH of 5.0 to 6.0 but can be grown in any soil. With any crop, a soil test can provide information necessary to make fertilizer recommendations, but if you do not do a soil test, a balanced fertilizer like 10-10-10 can work.

A common fertilization strategy is to apply one pound of fertilizer to every 10 feet of potato row before planting. Mix or rototill the fertilizer into the top 12 inches of the soil. One week after the plants emerge, band 0.5 pounds of fertilizer per 10 feet of potato row two inches from the plant and water the fertilizer in. Four to six weeks (about one and a half months) after emergence band another 0.5 pounds of fertilizer per 10 feet of potato row and water it in.

Potatoes require two inches of water a week. Infrequent or too heavy watering can cause growth cracks, irregular shapes, and hollow heart. To calculate the amount of water to apply, place a rain gauge or any container on the ground next to the potatoes. Turn on the sprinkler and when the water is two inches deep in the cup turn off the water. Potatoes’ highest water demand is from late June to early August. As the plant starts to turn yellow in late summer reduce the water, and the tubers will start to mature, and the skin will thicken.

For most home gardeners, chemical control of pests and weeds is not cost effective. Instead, rotate where you plant your crops in your garden each year. If you notice insects on your plants a stream of water can knock them off and reduce damage. Monitor your crops regularly for pests.

Disease can be reduced by maintaining clean tools, purchasing disease resistant seed and removing any plants that appear yellow, stunted, have shriveled leaves, or look different than healthy plants. Always discard the plants in the garbage. Do not place them in your compost bin.

Weeds should be identified and removed frequently as they can be a host to potato disease and compete for water and nutrients. This is especially true when the plant is less than 12 inches tall as fast-growing weeds can out compete potatoes for nutrients, water and sunlight. Whenever possible, remove the entire weed including its root from the soil.

Potatoes should be harvested before the first hard frost. You can tell if they are ready to be harvested if the vines are yellow or dead and if the skin on the potato is firm and does not peel when rubbed. Decreasing watering can help potatoes mature. Depending on the variety of potatoes you plant, you can expect about two pounds of potatoes per plant.

Store potatoes in a dark cool spot for two weeks with high humidity to help the skin to set or cure. Potatoes can be stored long-term in the dark at around 40°F. Air movement is important to prevent potatoes from going bad in storage.