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Spring break from teaching at U of L falls conveniently during the week of St. Patrick’s Day; which is also my target date for planting onions and potatoes. I typically manage a mid-March planting but the condition of the soil has held me up a bit this year. I will not start digging until the soil dries out and is considered workable. While we wait for that, select potato varieties that complement the way you cook. The most versatile varieties include favorites like Yukon Gold and Red Cloud. Both are great harvested early as “new” potatoes or harvested late for storage. If you have a history of pest problems in the potato patch then Island Sunshine and Prince Hairy prove most resistant; Elba and Butte are good mashed or baked; Caribe and Carola are best roasted or fried; and the fingerling potatoes are ideal for roasting whole.
This year I’ve decided on some Carola, Butte and All Blue. I base my annual selections on good production, taste and long-storage. It is best to purchase “certified disease-free” seed potatoes to prevent perpetuating disease in the garden. In the past I have had some fungal problems with fingerling potatoes so I am very aware of clean seed and rotating the crop; a brand new bed (for a nightshade crop) is waiting for this year’s seed potato to be planted, in fact.
Potatoes will grow in most soil types but hedge your bet by working lots of compost into the planting furrows; this will improve drainage (you can get planting sooner after a rain) and provide additional nutrients. Composted manure will provide the fertilizer requirements throughout the growing season. During the growing season, once the stems and foliage have emerged you can provide additional nutrients to the plants by spraying liquid seaweed or fish emulsion. Research suggests that fish emulsion deters deer grazing and some insect problems, as well.
Rotating your crop is essential for potatoes (and other vegetables in the nightshade family, like tomatoes) if you want to avoid pest problems. For most gardeners it is not too much to ask that they hand pick pests on a regular basis (and drop them in a bucket of water) in order to protect their potato crop but there are some biological controls that can help offset larger infestations of potato pests. Using floating row covers as an insect barrier early in season does a world of good in terms of protecting plants from Colorado potato beetles, leaf hoppers and flea beetles. If it gets really bad you can use Spinosad, a biological control.
When you are ready to plant cut the seed potatoes into sections, making sure that each section has 2 or 3 healthy buds or “eyes”. These eyes become the roots and stems of the tuber. You can usually get four good pieces from each seed potato. On average 5 pounds of seed potato will plant out a 50-foot row. Plant your seed potatoes in furrows, about 12 inches apart and about 3-5 inches deep, shallow for fast emergence deeper for less hilling duty. A long thin furrow makes it easier to harvest later in the summer.
You can warm the seed for a day or two before planting and plant shallowly initially for faster emergence. A couple of weeks after the foliage has emerged start hilling soil around the stem to protect the developing tubers. I plant on the deep side so I don’t have to hill the plants as much. The foliage takes longer to poke through the soil surface, just be patient.
Once the potatoes are hilled you can mulch with straw or other mulching material to moderate soil moisture, control weeds and to further protect the developing tubers from sun exposure. If the tubers are exposed to direct sunlight they turn green and take on a slight toxicity (they won’t kill you, though!)
You can harvest “new” potatoes after the plants have finished blooming but for larger potatoes suitable for storage allow plants to reach maturity. Harvest potatoes for storage about 3 weeks after the tops of the plants have completely died back. Rub off excess dirt and cure your potatoes in a ventilated and shaded (don’t leave them in the sun) area for a couple of weeks before rinsing and storing indoors (for successful, long storage you must allow the tops to die back and you must air cure them).