Growing Them Successfully

The practice of greening and pre-sprouting seed potatoes before planting encourages early growth and hastens the development of tubers. The method is simple: Spread the tubers in crates, boxes or flats, one layer to a flat. Bring the flats into a warm living space (70 degrees) and to a location where the light levels are medium in intensity. The warmth tends to stimulate the development of strong sprouts from the bud eye clusters. The benefits derived from greening and germinating the seed before planting are not limited to merely gaining a better stand and quicker maturity of the tubers, but it is claimed that a heavier yield is also likely.

Good potato soil will be well drained and moisture retentive. Sandy loam is ideal. Other soils can be improved by incorporating organic matter which tends to lighten heavy soil and enrich sandy soil. Potatoes grow best in a soil pH of 5.0 - 7.5. Optimum soil temperature for beginning growth ranges from 50-70 degrees. If your soil is compacted, you'll want to loosen it up with a shovel, fork, or rototiller. Add compost and mix in 6 to 8 inches. The compost will be the start of a nice batch of beneficial microbes. If using a rototiller, you'll want to work it in as deep as it goes. The long term goal for potato soil is to have a loose living soil full of beneficial microbes.

All tubers the size of a hen's egg (1-3 oz.) may be planted whole. For larger tubers, cut the potato using a clean, sharp knife so that each piece will contain 1 or more eyes. Pieces should be cut with plenty of flesh around the eyes, since the plant will utilize this stored food during the first 2 or 3 weeks of growth. Seeds may be planted immediately after cutting if you have good control of soil moisture. If there's a chance the soil may be too wet for a long period of time, you'll want to allow the cut pieces to dry out prior to planting. Spread them out on a table in the shade or one layer deep in shallow boxes for drying. Avoid shriveling which may weaken the seed piece. Also recommended for wet soil conditions is the application of sulfur or Fir bark dust to the freshly cut pieces. Place 1 or more tablespoons in a large paper bag, and toss the pieces around to cover them with dust. This may guard against threat of infection by bacteria and fungus in wetter soil.

The ideal planting time is 2 weeks before your last spring frost. (April 15th for Sonoma County) Then of course, you can plant anytime after that, giving yourself at least 3 months growing season before a major fall frost. The width between rows is determined by the size of your garden and method of cultivation. Farmers need 30” -36” between rows, while home gardeners can get by with 20” -26”. Dig a shallow trench about 6” - 8” deep. Plant your seed potatoes about 12” apart. Using a rake, cover the seed pieces immediately after planting. Do not cover too deep, 4” maximum, and leave the remaining soil for later.

In approximately two weeks, depending on soil temperature, green leaves will emerge. When the plants have grown to about 8" high, gently hill with soil brought up from both sides of the plant using a dull hoe. Bring the soil up about 3” inches leaving 4” - 6” of the plant exposed. Hilling cools the soil and creates space for tuber development. All tubers will form at the same depth of the seed piece and higher. Another hilling of 1 to 2” is beneficial 2 - 3 weeks later. Keep the blade of your hoe well away from the plants so you do not damage the roots. If you see potatoes poking out of the hills, add more soil to cover them. Hilling is crucial to establishing your crop. By gradually building an ever-larger hill of soil around the plant, you are building the site for your potatoes to develop. Give them plenty of room between rows and build your hills wide and ample to produce your bumper crop.

The Mulch Method is a good alternative if your soil is shallow, rocky or compact; if you're planting in the heat of summer, or have problems with scab in your soil. The best mulch to use is loose, seed-free hay or straw. Leaves and dried grass clippings can be used. It is important to have plenty on hand. Prepare your seed bed. Plant the seed pieces. They can be placed on the surface or lightly trenched, spaced as usual. Loosely shake mulch over the bed, 6" - 10" deep. As the plants grow, continue to add more loose straw, as if hilling. Be sure you keep the tubers well covered so that sunlight doesn't get to them and turn them green. The mulching method provides excellent weed and moisture control and reduces stress due to heat. At harvest, pull back mulch. Your nest of potatoes will be clean, uniform and easy to harvest.

Weeding is essential during this early part of the season. Using a hoe in a cultivating manner is a good way to check weeds when they are seedlings. Later, potato plants can canopy the soil and weed problems are slight. After hills are formed, mulch may be applied to retain moisture and suppress further weed growth.

Potatoes can be dry-land farmed where moisture retention and natural rainfall are adequate. However, if your summer is long and dry, your soil is sandy, or you would like to increase yields, you'll want to water. Potatoes need about 1 - 2” of water per week. Keep the soil evenly moist, but not too wet, from the time of emergence until the end of the season. Try not to let the soil completely dry out as this will cause sudden re-growth when watered, giving your tubers ears and noses, splits, or hollow heart. Each time you water, let it soak down 8 to 12”. A few thorough waterings, along with your efforts at hilling or mulching will be an adequate program to conserve soil moisture. Come up with a schedule, every three days or so, to check the soil moisture down at the roots. Stop or slow down watering at the end of the growing season when plants turn yellow and begin dying. But make sure the soil does not completely dry out. You want some soil moisture but not as much as during growth period.Harvesting in drier soil is easier and potatoes are better cured and ready for storage.

Other than green manures, the best organic fertilizer for potatoes is good compost mixed into the soil the fall before planting. You may also mix in some compost before planting, however make sure it is completely composted. Fresh manure will cause scab in potatoes. The sugar in molasses is a good way to enhance the health of potatoes and the soil by feeding and multiplying the beneficial soil microbes. Fill a 5 gallon bucket with water and add one cup of molasses to soak for a day and night. Place the bucket in the garden so that you can stir it when you walk by several times that day. Apply the liquid molasses so that it soaks into the root zone of the potatoes. Apply 1 to 4 times during the growing season. Another benefit to increasing the population of beneficial microbes in your soil is that they will compete against the harmful soil fungus that causes scab. Amazing results!

Gophers can literally undermine your best potato crop. They are best kept under control by trapping. We recommend the cinch trap. If you don't have the stomach for trapping, try growing potatoes in #15 gallon buckets or wine barrels.

In approximately 40 - 60 days after planting, the early potatoes may have blossomed. This is your sign that new potatoes may be ready, so carefully poke into the potato hill by hand to see what you can find. You may either "rob" from several plants, or simply harvest an entire plant from the end of your row. "Rob" gently to avoid injuring remaining roots and stressing the plant. They are delectable fresh treats creamed with new peas!

For later varieties used for winter storage, the plants should be mature, the foliage dead. Heavy frost will kill the top growth, or, if your tubers are up to size and there's no frost in sight, you can mow them or cut them by hand with a sickle. Drier soil is definitely an advantage when harvesting potatoes. When foliage dies, leave the tubers in the ground for two weeks. The skins will "cure" or toughen, protecting them from scuffing and bruising during harvest. This will help prolong storage life. Minor injuries can heal if allowed to dry. Harvest potatoes in the morning hours while it is still cool or warm - not hot. Or, if your soil is freezing at night, wait until the sun takes the frost out of the soil and then harvest. If hand digging, place your shovel outside the hill at first to avoid stabbing a good potato. If the soil is wet, let them air dry on the surface before gathering them.


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