Fall Planting Potatoes

Robert Smith
Adams County Master Gardener

Fall is bulb planting time, It also can be potato planting time. Flower bulbs in early fall; seed potatoes, late fall. One big difference between them though--flower bulbs should be planted before sprouting. Seed potatoes after sprouting. Sprouted seed potatoes planted before mid -December will produce thin-skinned ping-pong ball size new potatoes by late spring just in time to serve them creamed with your first garden peas. These little spuds don't have to be peeled. Just rub the skin off. Besides furnishing a delicious spring vegetable, fall planting does other good things for the garden:

  1. Early spring growth beats the weeds and later the spreading vines smother many spreading vines.
  2. Spring months usually have the cool soil and the 1" of rain per week potatoes need and summer months often lack. The tubers grow best with cool soil conditions. This year my fall planted potato crop had many more baking size (4" and up) than the Spring planted ones I have been digging now.

Fall planted potatoes will be ready to dig in time to plant a follow-up crop in rows already dug ready to plant.

Now is the time to order seed potatoes. Get them as early as possible to produce sprouts before planting. As soon as they arrive put them in plastic grocery bags and keep them in a warm bright place. A 70 temperature and high humidity will hasten sprouting. The ethylene from a newly picked apple in the bag can help sprouting too.

Five pounds of seed potatoes will plant two 20' rows. Good potato soil should be loose: growing tubers like to breathe. It should have some depth and be easily tilled, high in organic matter and on the acid side with a pH of 5.5-6.0. Good drainage is vital.

After most of the rest of the garden has been readied for the winter choose your potato planting area. Before tilling put down 1-1.5 lbs. of acid type fertilizer and 1 lb. of magnesium sulfate (Epsom Salts) plus about 1/2 cup of sulfur per 20' row. Dig an 8"-10" deep ditch on one side. For two rows dig two narrow 8"-10" deep drainage ditches 5' apart and between them two 8" deep furrows 30" apart . Throw the dug soil onto the center area to be available to hill up around the growing stems next spring. Fill the ditches and furrows with the cuttings of your fall grass and leaves, other shredded mulch or straw .It helps to cover the area with plastic to keep the planting area from freezing before planting.

When the potatoes sprout, ideally when sprouts are 1/4" out, you are ready to cut your seed. The pieces should be about1.5-2 ozs--about the size of a small egg. Small potatoes about that size can be planted whole. The cut pieces should be block shaped-no thin slices- with at least one eye or sprout but two are preferred. When cutting larger potatoes it is preferable to make a lengthwise cut at the top to divide the sprouts that usually cluster there, then make crosswise cuts to divide the rest into two-eye or one-eye blocks. Try to have a part of the center core of the potato in each piece. One pound of potatoes should produce 8-10 seeds. If you have time before planting it helps to let blocks or seeds "heal" by storing them a few days at 65-70 degrees with fairly high humidity. The surface develops a protective coat that can help prevent seed decay. Protect them from dehydrating with clear plastic film.

Don't worry too much about the planting date. Plantings after Xmas and in January have produced successful crops. The important thing is the soil preparation, especially preventing water from flooding the furrows .

The furrows should be about 8" deep so that the seed will have 4" of soil and 4"-6" of mulch over them .Space the seed10" to 12" apart. Gently firm 4" of soil over them, then about 6" of mulch. Put some long sticks in by the seed so when you get curious in early March you can check one without digging up the row. If there are apt to be voles in the vicinity scatter some castor oil scented grit on the mulch.

Keep a good mulch cover over the furrows to prevent freezing but do not cover with film. It is a housing invitation f or rodents. In the coldest winters the soil at seed depth has never gone below 36-37F. Roots on some varieties will show growth as temps stay over 40F. As spring creeps in check by the sticks for signs of sprouts but don't be in a hurry to remove mulch. Unprotected tips can get nipped by a heavy frost. If a hard freeze is forecast pull more mulch over the the rows the tips may be just below the surface.

When new growth reaches 4"-6" begin to cultivate and hill up around the stems. Don't cover the leaves. Continue to hill up as you cultivate . By the time the stalks are 14"-16" tall you should have 6"-8" hilled up. The stems under the earth will be sending out fine stems with tiny tubers so cultivate carefully. The hilling also helps keep the roots and other tuber stems cool. When you no longer need hill the stalks it is a good time to side dress the row using the acid type fertilizer then start spreading mulch in the rows to hold moisture and keep the soil cool

The tubers begin to set about a week or so before the blossoms begin to form .They come out about the middle of May About the first week of June snoop around under a few plants--very carefully--for the first little ones. When they are big enough to use, take them carefully , a few from each plant. There are a lot more coming along to enjoy late

Pick your peas. Cream your potatoes with just a touch of spring onion. A hint of mint on the peas .. Chervil and parsley on potatoes. Magnifique!! Bon Appetit!

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